Adjuvant chemotherapy for adenocarcinoma arising from intraductal papillary mucinous neoplasia: multicentre ADENO-IPMN study

BACKGROUND

The clinical impact of adjuvant chemotherapy after resection for adenocarcinoma arising from intraductal papillary mucinous neoplasia is unclear. The aim of this study was to identify factors related to receipt of adjuvant chemotherapy and its impact on recurrence and survival.

METHODS

This was a multicentre retrospective study of patients undergoing pancreatic resection for adenocarcinoma arising from intraductal papillary mucinous neoplasia between January 2010 and December 2020 at 18 centres. Recurrence and survival outcomes for patients who did and did not receive adjuvant chemotherapy were compared using propensity score matching.

RESULTS

Of 459 patients who underwent pancreatic resection, 275 (59.9%) received adjuvant chemotherapy (gemcitabine 51.3%, gemcitabine-capecitabine 21.8%, FOLFIRINOX 8.0%, other 18.9%). Median follow-up was 78 months. The overall recurrence rate was 45.5% and the median time to recurrence was 33 months. In univariable analysis in the matched cohort, adjuvant chemotherapy was not associated with reduced overall (P = 0.713), locoregional (P = 0.283) or systemic (P = 0.592) recurrence, disease-free survival (P = 0.284) or overall survival (P = 0.455). Adjuvant chemotherapy was not associated with reduced site-specific recurrence. In multivariable analysis, there was no association between adjuvant chemotherapy and overall recurrence (HR 0.89, 95% c.i. 0.57 to 1.40), disease-free survival (HR 0.86, 0.59 to 1.30) or overall survival (HR 0.77, 0.50 to 1.20). Adjuvant chemotherapy was not associated with reduced recurrence in any high-risk subgroup (for example, lymph node-positive, higher AJCC stage, poor differentiation). No particular chemotherapy regimen resulted in superior outcomes.

CONCLUSION

Chemotherapy following resection of adenocarcinoma arising from intraductal papillary mucinous neoplasia does not appear to influence recurrence rates, recurrence patterns or survival.

Opioid analgesia and severity of acute pancreatitis: An international multicentre cohort study on pain management in acute pancreatitis

BACKGROUND

The effect of analgesic modalities on short-term outcomes in acute pancreatitis remains unknown. However, preclinical models have raised safety concerns regarding opioid use in patients with acute pancreatitis.

OBJECTIVE

This study aimed to assess the association between analgesics, particularly opioids, and severity and mortality in hospitalised patients with acute pancreatitis.

METHODS

This prospective multicentre cohort study recruited consecutive patients admitted with a first episode of acute pancreatitis between April 1 and 30 June 2022, with a 1-month follow-up. Data on aetiology, clinical course, and analgesic treatment were collected. The primary outcome was the association between opioid analgesia and acute pancreatitis severity, which was analysed using univariate and multivariate analyses.

RESULTS

Among a total of 1768 patients, included from 118 centres across 27 countries, 1036 (59%) had opioids administered on admission day, and 167 (9%) received opioids after admission day. On univariate analysis, moderately severe or severe acute pancreatitis was associated with male sex, Asian ethnicity, alcohol aetiology, comorbidity, predicted severe acute pancreatitis, higher pain scores, longer pain duration and opioid treatment (all p < 0.001). On multivariate analysis, comorbidity, alcohol aetiology, longer pain duration and higher pain scores increased the risk of moderately severe or severe acute pancreatitis (all p < 0.001). Furthermore, opioids administered after admission day (but not on admission day) doubled the risk of moderately severe or severe disease (OR 2.07 (95% CI, 1.29-3.33); p = 0.003). Opioid treatment for 6 days or more was an independent risk factor for moderately severe or severe acute pancreatitis (OR 3.21 (95% CI, 2.16-4.79; p < 0.001). On univariate analysis, longer opioid duration was associated with mortality.

CONCLUSION

Opioid treatment increased the risk of more severe acute pancreatitis only when administered after admission day or for 6 days or more. Future randomised studies should re-evaluate whether opioids might be safe in acute pancreatitis.

Long-term Outcomes following Resection of Adenocarcinoma Arising from Intraductal Papillary Mucinous Neoplasm (A-IPMN) versus Pancreatic Ductal Adenocarcinoma (PDAC): A Propensity-score Matched Analysis

OBJECTIVE

The aim of the present study was to compare long-term post-resection oncological outcomes between A-IPMN and PDAC.

SUMMARY BACKGROUND DATA

Knowledge of long term oncological outcomes (e.g recurrence and survival data) comparing between adenocarcinoma arising from intraductal papillary mucinous neoplasms (A-IPMN) and pancreatic ductal adenocarcinoma (PDAC) is scarce.

METHODS

Patients undergoing pancreatic resection (2010-2020) for A-IPMN were identified retrospectively from 18 academic pancreatic centres and compared with PDAC patients from the same time-period. Propensity-score matching (PSM) was performed and survival and recurrence were compared between A-IPMN and PDAC.

RESULTS

459 A-IPMN patients (median age,70; M:F,250:209) were compared with 476 PDAC patients (median age,69; M:F,262:214). A-IPMN patients had lower T-stage, lymphovascular invasion (51.4%vs. 75.6%), perineural invasion (55.8%vs. 71.2%), lymph node positivity (47.3vs. 72.3%) and R1 resection (38.6%vs. 56.3%) compared to PDAC(P<0.001). The median survival and time-to-recurrence for A-IPMN versus PDAC were 39.0 versus19.5months (P<0.001) and 33.1 versus 14.8months (P<0.001), respectively (median follow-up,78 vs.73 months). Ten-year overall survival for A-IPMN was 34.6%(27/78) and PDAC was 9%(6/67). A-IPMN had higher rates of peritoneal (23.0 vs. 9.1%, P<0.001) and lung recurrence (27.8% vs. 15.6%, P<0.001) but lower rates of locoregional recurrence (39.7% vs. 57.8%; P<0.001). Matched analysis demonstrated inferior overall survival (P=0.005), inferior disease-free survival (P=0.003) and higher locoregional recurrence (P<0.001) in PDAC compared to A-IPMN but no significant difference in systemic recurrence rates (P=0.695).

CONCLUSIONS

PDACs have inferior survival and higher recurrence rates compared to A-IPMN in matched cohorts. Locoregional recurrence is higher in PDAC but systemic recurrence rates are comparable and constituted by their own distinctive site-specific recurrence patterns.

Intensive pre-operative information course (IPIC) and pre-operative weight loss results in long-term sustained weight loss following bariatric surgery: 11 years results from a tertiary referral centre

INTRODUCTION

Outcomes of long-term (5-10-year) weight loss have not been investigated thoroughly and the role of pre-operative weight loss on long-term weight loss, among other factors, are unknown. Our regional bariatric service introduced a 12 week intensive pre-operative information course (IPIC) to optimise pre-operative weight loss and provide education prior to bariatric surgery. The present study determines the effect of pre-operative weight loss and an intense pre-operative information course (IPIC), on long-term weight outcomes and sustained weight loss post-bariatric surgery.

METHODS

Data were collected prospectively from a bariatric center (2008-2022). Excess weight loss (EWL) ≥ 50% and ≥ 70% were considered outcome measures. Survival analysis and logistic regression identified variables associated with overall and sustained EWL ≥ 50% and ≥ 70%.

RESULTS

Three hundred thirty-nine patients (median age, 49 years; median follow-up, 7 years [0.5-11 years]; median EWL%, 49.6%.) were evaluated, including 158 gastric sleeve and 161 gastric bypass. During follow-up 273 patients (80.5%) and 196 patients (53.1%) achieved EWL ≥ 50% and ≥ 70%, respectively. In multivariate survival analyses, pre-operative weight loss through IPIC, both < 10.5% and > 10.5% EWL, were positively associated with EWL ≥ 50% (HR 2.23, p < 0.001) and EWL ≥ 70% (HR 3.24, p < 0.001), respectively. After a median of 6.5 years after achieving EWL50% or EWL70%, 56.8% (154/271) had sustained EWL50% and 50.6% (85/168) sustained EWL70%. Higher pre-operative weight loss through IPIC increased the likelihood of sustained EWL ≥ 50% (OR, 2.36; p = 0.013) and EWL ≥ 70% (OR, 2.03; p = 0.011) at the end of follow-up.

CONCLUSIONS

IPIC and higher pre-operative weight loss improve weight loss post-bariatric surgery and reduce the likelihood of weight regain during long-term follow-up.

A multicentre prospective evaluation of health-related quality of life and patient related outcomes in pancreatic and peripancreatic cancer: PROMCAN study

BACKGROUND

The temporal evolution of HRQoL and the importance of other PROs to patients, following resection for pancreatic and peripancreatic malignancy remains unexplored.

METHODS

Patients undergoing pancreatic resection between 2021 and 2022 were enrolled from 2 UK HPB centres. Patients completed the EORTC QLQ-C30, QLQ-PAN26 tools and rated 56 PROs preoperatively (T1), at discharge (T2), 6-weeks (T3), 3-months (T4) and 6-months (T5) postoperatively. ANOVA followed by post-hoc analysis was used to examine patterns in HRQoL through time. Multivariable ANOVA was used to identify impact of clinical factors on HRQoL.

RESULTS

63 patients were recruited [median age, 72 (IQR 41-85); 39/63 male]. Physical functioning declined from 70.4 (26.2) at T1 to 53.5 (20.9) at T2 (p = 0.016). Global QoL score increased significantly from 41.0 (23.0) at T2 to 60.0 (26.1) at T5 (p = 0.007), as did role functioning [21.1 (27.9) at T2 to 59.4 (32.8) at T5, p < 0.001]. Chemotherapy status and the postoperative complications did not significantly change HRQoL. General QoL and health were the only PROs rated as 'very important' (scores 7-9) by more than 80 % of participants at five time-points.

CONCLUSION

Recuperation of HRQoL measures is seen at 6-months postoperative and was not affected by chemotherapy or postoperative complications. Notably, PROs important to patients varied over time.

Validation of the updated Bosniak classification (2019) in pathologically confirmed CT-categorised cysts

INTRODUCTION

The updated Bosniak classification in 2019 (v2019) addresses vague imaging terms and revises the criteria with the intent to categorise a higher proportion of cysts in lower-risk groups and reduce benign cyst resections. The aim of the present study was to compare the diagnostic accuracy and inter-observer agreement rate of the original (v2005) and updated classifications (v2019).

METHOD

Resected/biopsied cysts were categorised according to Bosniak classifications (v2005 and v2019) and the diagnostic accuracy was assessed with reference to histopathological analysis. The inter-observer agreement of v2005 and v2019 was determined.

RESULTS

The malignancy rate of the cohort was 83.6% (51/61). Using v2019, a higher proportion of malignant cysts were categorised as Bosniak ≥ III (88.2% vs 84.3%) and a significantly higher percentage were categorised as Bosniak IV (68.9% vs 47.1%; p = 0.049) in comparison to v2005. v2019 would have resulted in less benign cyst resections (13.5% vs 15.7%). Calcified versus non-calcified cysts had lower rates of malignancy (57.1% vs 91.5%; RR,0.62; p = 0.002). The inter-observer agreement of v2005 was higher than that of v2019 (kappa, 0.70 vs kappa, 0.43).

DISCUSSION

The updated classification improves the categorisation of malignant cysts and reduces benign cyst resection. The low inter-observer agreement remains a challenge to the updated classification system.

Biogenesis, inheritance, and 3D ultrastructure of the microsporidian mitosome

During the reductive evolution of obligate intracellular parasites called microsporidia, a tiny remnant mitochondrion (mitosome) lost its typical cristae, organellar genome, and most canonical functions. Here, we combine electron tomography, stereology, immunofluorescence microscopy, and bioinformatics to characterise mechanisms of growth, division, and inheritance of this minimal mitochondrion in two microsporidia species (grown within a mammalian RK13 culture-cell host). Mitosomes of Encephalitozoon cuniculi (2-12/cell) and Trachipleistophora hominis (14-18/nucleus) displayed incremental/non-phasic growth and division and were closely associated with an organelle identified as equivalent to the fungal microtubule-organising centre (microsporidian spindle pole body; mSPB). The mitosome-mSPB association was resistant to treatment with microtubule-depolymerising drugs nocodazole and albendazole. Dynamin inhibitors (dynasore and Mdivi-1) arrested mitosome division but not growth, whereas bioinformatics revealed putative dynamins Drp-1 and Vps-1, of which, Vps-1 rescued mitochondrial constriction in dynamin-deficient yeast (Schizosaccharomyces pombe). Thus, microsporidian mitosomes undergo incremental growth and dynamin-mediated division and are maintained through ordered inheritance, likely mediated via binding to the microsporidian centrosome (mSPB).

Risk of Recurrence after Surgical Resection for Adenocarcinoma Arising from Intraductal Papillary Mucinous Neoplasia (IPMN) with Patterns of Distribution and Treatment: An International, Multicentre, Observational Study

OBJECTIVE

This international multicentre cohort study aims to identify recurrence patterns and treatment of first and second recurrence in a large cohort of patients after pancreatic resection for adenocarcinoma arising from IPMN.

SUMMARY BACKGROUND DATA

Recurrence patterns and treatment of recurrence post resection of adenocarcinoma arising from IPMN are poorly explored.

METHOD

Patients undergoing pancreatic resection for adenocarcinoma from IPMN between January 2010 to December 2020 at 18 pancreatic centres were identified. Survival analysis was performed by the Kaplan-Meier log rank test and multivariable logistic regression by Cox-Proportional Hazards modelling. Endpoints were recurrence (time-to, location, and pattern of recurrence) and survival (overall survival and adjusted for treatment provided).

RESULTS

Four hundred and fifty-nine patients were included (median, 70 y; IQR, 64-76; male, 54 percent) with a median follow-up of 26.3 months (IQR, 13.0-48.1 mo). Recurrence occurred in 209 patients (45.5 percent; median time to recurrence, 32.8 months, early recurrence [within 1 y], 23.2 percent). Eighty-three (18.1 percent) patients experienced a local regional recurrence and 164 (35.7 percent) patients experienced distant recurrence. Adjuvant chemotherapy was not associated with reduction in recurrence (HR 1.09;P=0.669) One hundred and twenty patients with recurrence received further treatment. The median survival with and without additional treatment was 27.0 and 14.6 months (P<0.001), with no significant difference between treatment modalities. There was no significant difference in survival between location of recurrence (P=0.401).

CONCLUSION

Recurrence after pancreatic resection for adenocarcinoma arising from IPMN is frequent with a quarter of patients recurring within 12 months. Treatment of recurrence is associated with improved overall survival and should be considered.

The impact of surgical set-up of endoscopic two surgeon four hand anterior skull base surgeries on surgeons' ergonomics

BACKGROUND

The impact of different surgical set-ups of endoscopic two surgeon four hand anterior skull base surgeries on surgeons' ergonomics remain unclear. This study aims to explore the effect of surgeon, patient and surgical screen positioning on surgeons' ergonomics using the Rapid Entire Body Assessment (REBA) tool.

METHODS

A total of 20 different surgical positions of anterior skull base surgery were simulated and the ergonomic impact on surgeons' neck, truck, leg and wrist were measured using the validated Rapid Entire Body Assessment (REBA) tool. To investigate the ergonomic effect of different surgical setups, the operating surgeon, assisting surgeon, patient head, camera and screen positions were positioned differently in each surgical position.

RESULTS

The lowest REBA Score recorded is 3 whereas the highest score is 8. The REBA scores for the majority of positions are 3 highlighting that these positions are ergonomically favorable. Position 12 is the least ergonomically favorable position with a total REBA score of 19. In this position, operating surgeon is positioned to the right of the patient, assisting surgeon to the left of patient, patient head in central position with camera held by operating surgeon and one screen is placed to the right of patient. Positions 13 and 17 are the most ergonomically favorable positions with a total REBA score of 12. In these positions, the patient's head is positioned to the center, two screens were utilized, and the surgeons were positioned on either side of the patient. The utilization of 2 screens with a central patient head position with the surgeons placed on either side of the patient contribute towards a more ergonomically state in these positions.

CONCLUSIONS

Certain positional behaviors are better at reducing musculoskeletal injury risk when compared to other. Positions with two screens and central head positions are more favourable ergonomically and surgeons should consider this set-up to reduce musculoskeletal injuries during anterior skull base surgery.

Defining Prolonged Length of Stay (PLOS) Following Elective Laparoscopic Cholecystectomy and Derivation of a Preoperative Risk Score to Inform Resource Utilization, Risk Stratification, and Patient Consent

OBJECTIVE

The present study defines prolonged length of stay (PLOS) following elective laparoscopic cholecystectomy (LC) and its relationship with perioperative morbidity. A preoperative risk tool to predict PLOS is derived to inform resource utilization, risk stratification and patient consent.

BACKGROUND

Surgical candidates for elective LC are a heterogeneous group at risk of various perioperative adverse outcomes. Preoperative recognition of high-risk patients for PLOS has implications on feasibility for day surgery, resource utilization, preoperative risk stratification, and patient consent.

METHODS

Data for all patients who underwent elective LC between January 2015 and January 2020 across 3 surgical centers (1 tertiary referral center and 2 satellite units) in 1 health board were collected retrospectively (n=2166). The optimal cut-off of PLOS as a proxy for operation-related adverse outcomes was found using receiver operating characteristic curves. Multivariate logistic regression was conducted on a derivation subcohort to derive a preoperative model predicting PLOS. Receiver operating characteristic curves were performed to validate the model. Patients were stratified by the risk tool and the risks of PLOS were determined.

RESULTS

A LOS of ≥3 days following elective LC demonstrated the best diagnostic ability for operation-related adverse outcomes [area under curve (AUC)=0.87] and defined the PLOS cut-off. The rate of PLOS was 6.6% (144/2166), 86.1% of which had a perioperative adverse outcome. PLOS was strongly associated with all adverse outcomes (subtotal, conversion-to-open, intraoperative complications, postoperative complication/imaging/intervention) ( P <0.001). The preoperative model demonstrated good diagnostic ability for PLOS in the derivation (AUC=0.81) and validation cohorts (AUC=0.80) and stratified patients appropriately.

CONCLUSIONS

Morbidity in PLOS patients is significant and pragmatic patient selection in accordance with the risk tool may help centers improve resource utilization, risk stratification, and their consent process. The risk tool may help select candidates for cholecystectomy in a strictly ambulatory/outpatient center.

Laparoscopic Lumen-guided cholecystectomy in face of the difficult gallbladder

BACKGROUND

Where the critical view of safety cannot be established during cholecystectomy, certain salvage techniques are indicated to reduce the likelihood of bile duct injury. The present study describes a salvage technique termed the "laparoscopic lumen-guided cholecystectomy" (LLC) and reports its peri-operative outcomes.

METHOD

A summary of the technique is as follows: (1) Hartmann's pouch is incised and stones are evacuated; (2) the cystic anatomy is inspected from the inside of the gallbladder; (3) the lumen is used to guide retrograde dissection towards the cystic pedicle; (4) cystic duct control is achieved if deemed safe. LLC cases performed between June 2020 and January 2022 in a single health board were included. The operative details and peri-operative outcomes of the technique are reported and compared to cases of similar difficulty where the LLC was not attempted.

RESULTS

LLC was performed in 4.6% (27/587) of cases. In all 27 cases, LLC was performed for a "frozen" cholecystohepatic triangle. Hartmann's pouch was completely excised in all cases (27/27) and cystic duct control was achieved in 85.2% of cases (23/27). No cases of bile leak or ductal injury were reported. Rates of bile leak, post-operative complications and ERCP were lower following LLC compared to the group where LLC was not attempted (p < 0.01).

CONCLUSION

LLC is a safe salvage technique and should be considered in cases where the critical view of safety cannot be established. The technique achieves cystic duct control in the majority of cases and favourable outcomes in the face of a difficult cholecystectomy.

HPB P23 Laparoscopic lumen-guided cholecystectomy in face of the difficult gallbladder

Background

Where the critical view of safety cannot be established during cholecystectomy, certain salvage techniques are indicated to reduce the likelihood of bile duct injury. The present study describes a salvage technique termed the “laparoscopic lumen-guided cholecystectomy” (LLC) and reports its peri-operative outcomes.

Methods

A summary of the technique is as follows: (1) Hartmann's pouch is incised and stones are evacuated; (2) the cystic anatomy is inspected from the inside of the gallbladder; (3) the lumen is used to guide retrograde dissection towards the cystic pedicle; (4) cystic duct control is achieved if deemed safe. LLC cases performed between June 2020 and January 2022 in a single health board were included. The operative details and peri-operative outcomes of the technique are reported and compared to cases of similar difficulty (Nassar ≥4) where the LLC was not attempted.

Results

LLC was performed in 4.6% (27/587) of cases. In all 27 cases, LLC was performed for a “frozen” cholecystohepatic triangle. Hartmann's pouch was completely excised in all cases (27/27) and cystic duct control was achieved in 85.2% of cases (23/27). No cases of bile leak or ductal injury were reported. Rates of bile leak, post-operative complications and ERCP were lower following LLC compared to the group where LLC was not attempted (p&lt;0.01).

Conclusions

LLC is a safe salvage technique and should be considered in cases where the critical view of safety cannot be established. The technique achieves cystic duct control in the majority of cases and favourable outcomes in the face of a difficult cholecystectomy.

Anastomotic Leak in Ovarian Cancer Cytoreduction Surgery: A Systematic Review and Meta-Analysis

Simple Summary

Bowel resection is often required to obtain complete removal of ovarian cancer. A major complication of this operation is anastomotic leakage, which has been shown to increase morbidity and mortality in this population. Numerous original research studies have assessed the risk factors for anastomotic leaks. We aimed to conduct a systematic review and meta-analysis to identify statistically significant risk factors. This meta-analysis identified multiple bowel resections as the only significant risk factor. With further research to identify additional risk factors, new management guidelines could be implemented to minimize the risk of anastomotic leaks and improve patient outcomes.

Abstract

Introduction: Anastomotic leaks (AL) following ovarian cytoreduction surgery could be detrimental, leading to significant delays in commencing adjuvant chemotherapy, prolonged hospital stays and increased morbidity. The aim of this study was to investigate risk factors associated with anastomotic leaks after ovarian cytoreduction surgery. Material and methods: The MEDLINE (via PubMed), Cochrane Library, EMBASE and Scopus bibliographical databases were searched. Original clinical studies investigating risk factors for AL in ovarian cytoreduction surgery were included. Results: Eighteen studies with non-overlapping populations reporting on patients undergoing cytoreduction surgery for ovarian cancer (n = 4622, including 344 cases complicated by AL) were included in our analysis. Patients undergoing ovarian cytoreduction surgery complicated by AL had a significantly higher rate of 30-day mortality but no difference in 60-day mortality. Multiple bowel resections were associated with an increased risk of postoperative AL, while no association was observed with body mass index (BMI), American Society of Anesthesiologists (ASA) score, age, smoking, operative approach (primary versus interval cytoreductive, stapled versus hand-sewn anastomoses and formation of diverting stoma), neoadjuvant chemotherapy and use of hyperthermic intraperitoneal chemotherapy (HIPEC). Discussion: Multiple bowel resections were the only clinical risk factor associated with increased risk for AL after bowel surgery in the ovarian cancer population. The increased 30-day mortality rate in patients undergoing ovarian cytoreduction complicated by AL highlights the need to minimize the number of bowel resections in this population. Further studies are required to clarify any association between neoadjuvant chemotherapy and decreased AL rates.

Morbidity following emergency and elective cholecystectomy: a retrospective comparative cohort study

INTRODUCTION

An emergency laparoscopic cholecystectomy (EMLC) is commonly performed for all biliary pathology, yet EMLC can be challenging due to acute inflammation. Understanding the risks of EMLC is necessary before patients can make an informed decision regarding operative management. The aim of the present study was to compare rates of operative and post-operative outcomes between EMLC and elective LC (ELLC) using a large contemporary cohort, to inform the consent process and influence surgical decision making.

METHODS

All patients who underwent EMLC and ELLC in one UK health board between January 2015 and December 2019 were considered for inclusion. Data were collected retrospectively from multiple regional databases using a deterministic records-linkage methodology. Patients were followed up for 100 days post-operatively for adverse outcomes and outcomes were compared between groups using both univariate and multivariate analysis adjusting for pre-operative factors.

RESULTS

A total of 2768 LCs were performed [age (range), 52(13-92); M:F, 1:2.7]. In both the univariate and multivariate analysis, EMLC was positively associated with subtotal cholecystectomy (RR 2.0; p < 0.001), post-operative complication (RR 2.8; p < 0.001), post-operative imaging (RR 2.0; p < 0.001), post-operative intervention (RR 2.3; p < 0.001), prolonged post-operative hospitalisation (RR 3.8; p < 0.001) and readmission (RR 2.2; p < 0.001). EMLC had higher rates of post-operative mortality in univariate analysis (RR 10.8; p = 0.01).

DISCUSSION

EMLC is positively associated with adverse outcomes versus ELLC. Of course this study does not focus on a specific biliary pathology; nevertheless, it illustrates the additional risk associated with EMLC. This should be clearly outlined during the consent process but should be balanced with the risk of further biliary attacks. Further studies are required to identify particular patient groups who benefit from elective surgery.

The Variation in Outcomes of Septic Patients: A Dual-Centre Comparative Study

Introduction Despite significant advances in the field of medicine, sepsis is constantly growing as a major public health concern. The global epidemic of sepsis imposes a significant economic burden on healthcare systems world-over. Furthermore, its high prevalence in society is inevitably paralleled by an excessive mortality rate, with approximately six million deaths reported every year. The primary aim of this study was to evaluate and compare, the management of acutely septic patients against outcomes in a tertiary teaching institution in Pakistan versus a similar one in the United Kingdom. Methods This study was a dual-centred, retrospective comparative analysis comparing all patients admitted through the emergency department at the respective tertiary centres. Patient details were collected and compared across the two sites to evaluate the effect of individual characteristics on prognosis. The outcomes of these presentations were analysed by comparing rates of in-hospital mortality, admission to the ICU or discharge. Results The total number of patients identified as having sepsis was 60 in the Pakistan cohort, and 92 in the Aberdeen cohort. No significant difference was found when comparing genders, and the results of basic observations were largely similar at presentation. Twenty-five per cent (25%) (n=38) of the total study population were deemed to have a poor outcome at 3 days, but 50% of the Pakistan cohort was deemed to have a poor outcome. Conclusion Managing sepsis has developed significantly in recent years, but most of this development was implemented in high-income countries. There was a significant delay in time to resuscitate septic patients in Pakistan, with significantly raised three-day morbidity and mortality. There is a need for further comparative studies of the management of sepsis in Pakistan and other low-income countries to identify the problems and tackle obstacles on every level of the healthcare system.

Elective laparoscopic cholecystectomy: recurrent biliary admissions predispose to difficult cholecystectomy

INTRODUCTION

Patients undergoing elective laparoscopic cholecystectomy (ELLC) represent a heterogeneous group making it challenging to stratify risk. The aim of this paper is to identify pre-operative factors associated with adverse peri- and post-operative outcomes in patients undergoing ELLC. This knowledge will help stratify risk, guide surgical decision making and better inform the consent process.

METHODS

All patients who underwent ELLC between January 2015 and December 2019 were included in the study. Pre-operative data and both peri- and post-operative outcomes were collected retrospectively from multiple databases using a deterministic records-linkage methodology. Patients were divided into groups based on clinical indication (i.e. biliary colic versus cholecystitis) and adverse outcomes were compared. Multivariate regression models were generated for each adverse outcome using pre-operative independent variables.

RESULTS

Two-thousand one hundred and sixty-six ELLC were identified. Rates of peri- and post-operative adverse outcomes were significantly higher in the cholecystitis versus biliary colic group and increased with number of admissions of cholecystitis (p < 0.05). Rates of subtotal (29.5%), intra-operative complication (9.8%), post-operative complications (19.6%), prolonged post-operative stay (45.9%) and re-admission (16.4%) were significant in the group of patients with ≥ 2 admissions with cholecystitis.

CONCLUSION

Our data demonstrate that patients with repeated biliary admission (particularly cholecystitis) ultimately face an increased risk of a difficult ELLC with associated complications, prolonged post-operative stay and readmissions. These data provide robust evidence that individualised risk assessment and consent are necessary before ELLC. Strategies to minimise recurrent biliary admissions prior to LC should be implemented.

Evaluation of Textbook Outcome as a Composite Quality Measure of Elective Laparoscopic Cholecystectomy

IMPORTANCE

A textbook outcome (TO) is a composite quality measure that incorporates multiple perioperative events to reflect the most desirable outcome. The use of TO increases the event rate, captures more outcomes to reflect patient experience, and can be used as a benchmark for quality improvement.

OBJECTIVES

To introduce the concept of TO to elective laparoscopic cholecystectomy (LC), propose the TO criteria, and identify characteristics associated with TO failure.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study was performed at 3 surgical units in a single health board in the United Kingdom. Participants included all patients undergoing elective LC between January 1, 2015, and January 1, 2020. Data were analyzed from January 1, 2015, to January 1, 2020.

MAIN OUTCOMES AND MEASURES

The TO criteria were defined based on review of existing TO metrics in the literature for other surgical procedures. A TO was defined as an unremarkable elective LC without conversion to open cholecystectomy, subtotal cholecystectomy, intraoperative complication, postoperative complications (Clavien-Dindo classification ≥2), postoperative imaging, postoperative intervention, prolonged length of stay (>2 days), readmission within 100 days, or mortality. The rate of TOs was reported. Reasons for TO failure were reported, and preoperative characteristics were compared between TO and TO failure groups using both univariate analysis and multivariable logistic regressions.

RESULTS

A total of 2166 patients underwent elective LC (median age, 54 [range, 13-92] years; 1579 [72.9%] female). One thousand eight hundred fifty-one patients (85.5%) achieved a TO with an unremarkable perioperative course. Reasons for TO failure (315 patients [14.5%]) included conversion to open procedure (25 [7.9%]), subtotal cholecystectomy (59 [18.7%]), intraoperative complications (40 [12.7%]), postoperative complications (Clavien-Dindo classification ≥2; 92 [29.2%]), postoperative imaging (182 [57.8%]), postoperative intervention (57 [18.1%]), prolonged length of stay (>2 days; 142 [45.1%]), readmission (130 [41.3%]), and mortality (1 [0.3%]). Variables associated with TO failure included increasing American Society of Anesthesiologists score (odds ratio [OR], 2.55 [95 CI, 1.69-3.85]; P < .001), increasing number of prior biliary-related admissions (OR, 2.68 [95% CI, 1.36-5.27]; P = .004), acute cholecystitis (OR, 1.42 [95% CI, 1.08-1.85]; P = .01), preoperative endoscopic retrograde cholangiopancreatography (OR, 2.07 [95% CI, 1.46-2.92]; P < .001), and preoperative cholecystostomy (OR, 3.22 [95% CI, 1.54-6.76]; P = .002).

CONCLUSIONS AND RELEVANCE

These findings suggest that applying the concept of TO to elective LC provides a benchmark to identify suboptimal patterns of care and enables institutions to identify strategies for quality improvement.

The impact on complication rates of delayed routine pessary reviews during the COVID-19 pandemic

Introduction and hypothesis

During the COVID-19 pandemic, guidance was issued in the United Kingdom advising a delay in routine pessary reviews. The impact of this has not been fully explored. The null hypothesis for this study is that delayed routine pessary reviews during the COVID-19 pandemic did not result in a statistically significant increase in complication rate.

Methods

A retrospective comparative cohort study was conducted in NHS Tayside, Scotland, involving 150 patients pre-pandemic and 150 patients during the COVID-19 pandemic (before exclusions). Their notes were reviewed identifying age, care provider, pessary type, length of pessary usage, review date, time elapsed since the previous review, bleeding/infection/ulceration, removal issues, pessary replacement and outcome. Patients excluded were those with no pessary in situ at review, reviews at ≤4 months and >8 months (pre-pandemic) and reviews at ≤8 months (COVID-19 pandemic).

Results

The pre-pandemic group (n=106) had average review times of 10.1,6.2 and 6.2 months for cubes, rings and all others. Overall rates of bleeding/infection/ulceration; reported removal issues; and pessary subsequently not replaced were 9.4%, 11.3% and 5.7% respectively. The COVID-19 pandemic group (n=125) had average review times of 14.7, 10.8 and 11.4 months for cubes, rings and all others. Overall rates of bleeding/infection/ulceration; reported removal issues; and pessary subsequently not replaced were 21.6%, 16.0%, and 12.0% respectively.

Conclusions

Overall, there was a significant increase in rates of bleeding/ulceration/infection (p=0.01). When individual pessaries were considered, this only remained true for rings (p=0.02). Our data would suggest that routine ring pessary reviews should not be extended beyond 6 months or risk bleeding/ulceration/infection.

Negative Appendicectomy Rates in Females of Childbearing Age: A Retrospective Analysis and Literature Review

Introduction

A negative appendicectomy rate (NAR) is defined as the portion of pathologically normal appendices removed surgically in patients suspected of having acute appendicitis. The lifetime risk of acute appendicitis is 8.6% for males and 6.7% for females; contrarily, the lifetime risk of appendicectomy is 12% for males and 23.1% for females. This study aims primarily to evaluate the true NAR in females of childbearing age to offer insight into potential strategies to reduce the number of unnecessary operative procedures carried out, along with their associated morbidity and mortality.

Methods

All emergency appendicectomies over a one-year period were retrospectively identified and collected from a single tertiary care centre. Preoperative clinical, laboratory and postoperative histopathological data were collected. The negative appendicectomy rate in subgroups divided by biomarkers and radiological imaging findings were analysed. The diagnostic value of these modalities in the context of acute appendicitis was found by calculating the sensitivity, specificity, positive predictive values, and negative predictive values.

Results

A total of 417 patients were included (median age 26; M:F, 0.7:1.0). The overall negative appendicectomy rate was 35.0% (146/417). Two-hundred sixty-one patients underwent an appendicectomy in the child-bearing age group. The NAR was significantly higher in those females with raised WBC and C-reactive protein (CRP) compared to their male counterparts (p-value -<0.001).

Conclusion

Women of childbearing age have a higher NAR of 43% when compared to the general population of 35%. Preoperative tests, including ultrasound scans, computed tomography and inflammatory markers in blood tests, help direct those who would benefit from surgery to the operating theatre, however, no test alone is suitably sensitive or specific. To reduce the NAR, management options include a return to observation and serial examination, increased use of low-dose CT or a commitment to improving the performance of ultrasonography.

Acute cholecystitis: Delayed cholecystectomy has lesser perioperative morbidity compared to emergency cholecystectomy

BACKGROUND

In comparison to delayed laparoscopic cholecystectomy, emergency laparoscopic cholecystectomy has a shorter length of stay and eliminates the risk of recurrent episodes of acute cholecystitis. Nevertheless, there is concern that emergency laparoscopic cholecystectomy is associated with higher morbidity in acute cholecystitis patients. The present large cohort study compares operation-related adverse outcomes between emergency and delayed laparoscopic cholecystectomy and determines the risk of readmission before delayed laparoscopic cholecystectomy to guide surgical decision-making.

METHODS

Patients diagnosed with acute cholecystitis who underwent emergency or delayed laparoscopic cholecystectomy between 2015 and 2019 were included. Perioperative outcomes were compared using univariate and multivariate analysis, adjusting for preoperative variables. The rate of readmission before delayed laparoscopic cholecystectomy was determined.

RESULTS

In total, 811 patients were included (median age, 58 years; male:female, 1:1.5): 227 emergency laparoscopic cholecystectomies (28.0%), 555 delayed laparoscopic cholecystectomies (68.4%), and 29 emergency laparoscopic cholecystectomies whilst awaiting delayed laparoscopic cholecystectomy (3.6%). Emergency laparoscopic cholecystectomy was associated with increased incidences of subtotal cholecystectomy (OR 1.94; P = .011), bile leak (OR 2.38; P = .013), intraoperative drains (OR 2.54; P < .001), prolonged postoperative length of stay (OR 7.26; P < .001), postoperative imaging (OR 1.83, P = .006), and postoperative readmission (OR 1.90; P = .005). There was a 13.5% risk of readmission over 2 months while waiting delayed laparoscopic cholecystectomy and a 22.5% risk over the median waiting time (5 months, 9 days).

CONCLUSION

Emergency laparoscopic cholecystectomy is positively associated with a multitude of operation-related adverse outcomes in acute cholecystitis, compared to delayed laparoscopic cholecystectomy. The benefit of delayed laparoscopic cholecystectomy should be balanced against the significant readmission risk before delayed laparoscopic cholecystectomy. Emergency laparoscopic cholecystectomy may be the most pragmatic strategy for centers dealing with high volumes of biliary admissions and long elective-surgery waiting times. When opting for delayed laparoscopic cholecystectomy, confirming the date of surgery before discharge may ensure timely intervention and avoid the morbidity and expense of readmission.

Follow-up after emergency laparotomy suggests high one- and five-year mortality with risk stratified by ASA

INTRODUCTION

We investigated all-cause mortality following emergency laparotomy at 1 and 5 years. We aimed to establish a basis from which to advise patients and relatives on long-term mortality.

METHODS

Local data from a historical audit of emergency laparotomies from 2010 to 2012 were combined with National Emergency Laparotomy Audit (NELA) data from 2017 to 2020. Covariates collected included deprivation status, preoperative blood work, baseline renal function, age, American Society of Anesthesiologists (ASA) grade, operative time, anaesthetic time and gender. Associations between covariates and survival were determined using multivariate logistic regression and Kaplan-Meier analysis. We used patients undergoing laparoscopic cholecystectomy between 2015 and 2020 as controls.

RESULTS

ASA grade was the best discriminator of long-term outcome following laparotomy (n=894) but was not a predictor of survival following cholecystectomy (n=1,834), with mortality being significantly greater in the laparotomy group. Following cholecystectomy, 95% confidence intervals for survival at 5 years were 98-99%. Following laparotomy these intervals were: ASA grade 1, 79-96%; ASA grade 2, 69-82%; ASA grade 3, 44-58%; ASA grade 4, 33-48%; and ASA grade 5, 4-51%. The majority of deaths occurred after 30 days.

CONCLUSIONS

Emergency laparotomy is associated with a significantly increased risk of death in the following 5 years. The risk is strongly correlated to ASA grade. Thirty-day mortality estimation is not a good basis on which to advise patients and carers on long-term outcomes. ASA grade can be used to predict long-term outcomes and to guide patient counsel.

47 Patient and Physician Positioning During Anterior Skull Base Surgery Impacts Physician Ergonomics

Aim

The effects of anterior skull base surgery on surgeon’s ergonomics remain unclear and this study explore the impact of patient, surgeon, and screen positioning on surgeon’s ergonomics during the surgery.

Method

A total of 20 different surgical positions involving the operating surgeon, assisting surgeon, patient head position, camera position and screen position/number were simulated. For each position, the ergonomic effects on the upper limb, neck, trunk, and lower limb of surgeons were analysed using the Rapid Upper Limb Assessment (RULA) tool.

Results

The majority of scores ranged from 2 to 3 suggesting the majority of positions have acceptable postures. The average RULA score of the right side of operating surgeon was 2.8 versus 2.95 on the left-side (p = 0.297). For the assisting surgeon, the average RULA score of the right side was 3.65 versus 3.25 for the left side (p = 0.053). The average combined (left and right) RULA score for the operating surgeon was 5.76 versus 6.9 for the assisting surgeon (p&lt;0.001). Position 17 (operating surgeon to the right of patient, assisting surgeon to the left of patient, central patient head position and two screens) is the most ergonomically favourable position. Position 2 (operating and assisting surgeon to the right of patient, patient head position to the right and one screen position to the left of patient) is the least favourable position.

Conclusions

This simulation raises awareness of risk of musculoskeletal injury in anterior skull base surgery and highlights those certain positional behaviours are better for reducing injury risk than others.

Subtotal Cholecystectomy Results in High Peri-operative Morbidity and Its Risk-Profile Should be Emphasised During Consent

BACKGROUND

Subtotal cholecystectomy aims to reduce the likelihood of bile duct injury but risks a multitude of less severe, yet significant complications. The primary aim of the present study was to report peri-operative outcomes of subtotal laparoscopic cholecystectomy (SLC) relative to total laparoscopic cholecystectomy (TLC) to inform the consent process.

METHOD

All laparoscopic cholecystectomies between 2015 and 2020 in one health board were included. The peri-operative outcomes of SLC (n = 87) and TLC (n = 2650) were reported. Pre-operative variables were compared between the two groups to identify risk factors for SLC. The outcomes between the SLC and TLC were compared using univariate, multivariate and propensity analysis.

RESULTS

Risk factors for SLC included higher age, male gender, cholecystitis, increased biliary admissions, ERCP, cholecystostomy and emergency cholecystectomy. Following SLC, rates of post-operative complication (45.9%), imaging (37.9%) intervention (28.7%) and readmission (29.9%) were significant. The risk profile was vastly heightened compared to that of TLC: intra-operative complications (RR 9.0; p < 0.001), post-operative complications [bile leak (RR 58.9; p < 0.001), collection (RR 12.2; p < 0.001), retained stones (RR 7.2; p < 0.001) and pneumonia (RR 5.4; p < 0.001)], post-operative imaging (RR 4.4; p < 0.001), post-operative intervention (RR 12.3; p < 0.001), prolonged PLOS (RR 11.3; p < 0.001) and readmission (RR 4.5; p < 0.001). The findings were consistent using multivariate logistic regression and propensity analysis.

CONCLUSION

The relative morbidity associated with SLC is significant and high-risk patients should be counselled for the peri-operative morbidity of subtotal cholecystectomy.

P-BN51 Subtotal cholecystectomy: risk factors and patient outcomes

Background

A subtotal cholecystectomy (SC) is indicated when a total cholecystectomy (TC) cannot be achieved without the risk of causing significant harm, the most feared complication being a bile duct injury. The aims of the present study were to identify patients at risk of SC, to compare the peri- and post-operative course between SC and TC and to compare outcomes between fenestrated and reconstituting subtypes.

Methods

All planned laparoscopic cholecystectomies across three surgical units over a population of 493,000 between 2015 and 2019 were considered. Data were collected retrospectively using electronic databases and included pre-operative, operative and post-operative data over a 100-day follow-up period. Variables associated with SC were identified using multivariate logistic regression. Outcomes following SC were compared with TC using univariate analysis, specifically chi-squared and Mann-Whitney U tests. The subtype of SC was documented and outcomes were compared between groups.

Results

The rate of SC was 3.4% (94/2768). Variables positively associated with SC included male sex (OR-2.33;p&lt;0.001), age≥60 (OR-1.79;p=0.009), 2 previous admissions (OR-1.76;p=0.043), ≥3 previous admissions (OR-3.10;p=0.003), emergency cholecystectomy (OR-2.01;p=0.002); cholecystitis (OR-4.92;p&lt;0.001) and pre-operative ERCP (OR-2.23;p&lt;0.002). Patients with SC versus TC were more likely to suffer intra-operative complications (RR-13.1;p&lt;0.001), post-operative complication (RR-6.7;p&lt;0.001), require post-operative imaging/intervention (RR-4.0;p&lt;0.001) and be re-admitted (RR-4.2; p &lt; 0.001). The rate of bile duct injury was 0% in SC patients. The rate of post-operative bile leak was higher where the cystic duct was left open versus closed (RR-2.9;p=0.03) and in fenestrating SC versus reconstituting SC (35.7% versus 0%;p=0.002). Drain duration was reduced in reconstituting SC (p &lt; 0.001).

Conclusions

The risk of SC can be explained by a number of patient specific factors and the risk should be emphasized in these patients during the consent process and should influence surgical decision making. The morbidity following a subtotal cholecystectomy is markedly higher than that of a total cholecystectomy but can be performed without significant risk of bile duct injury. Reconstituting SC and closure of the cystic duct reduces rates of post-operative bile leaks and duration of drains.

P-BN60 Predicting post-operative length of stay following laparoscopic cholecystectomy: derivation and validation of a pre-operative risk score

Background

To predict the post-operative length of stay following laparoscopic cholecystectomy (LC) will help guide the utilisation of resources, particularly the allocation of day surgery beds.  Prolonged post-operative stay (PPS) is associated with morbidity and the acknowledgement of pre-operative factors predisposing to morbidity and PPS will influence surgical decision-making. The aim of the present study was to determine pre-operative factors associated with PPS and both derive and validate a risk score to predict the risk of PPS following LC.

Methods

Patients who underwent emergency and elective LC between January 2015 and December 2019 across three surgical centres were included. Pre-operative, operative and post-operative data were collected retrospectively from multiple databases using a deterministic records-linkage methodology. The cohort was randomly divided into a derivation and validation cohort, by a 3:1 ratio, respectively. The derivation cohort was used to create a risk score for PPS (≥3 days post-operatively) using multivariate logistic regression. The risk score was then applied to the smaller set or ‘validation cohort’ for internal validation purposes and the predictive accuracy was assessed using a ROC curve.

Results

The rate of PPS was 10.6% (294/2768). PPS was associated with intra-operative complication (RR-17.0;p&lt;0.001), bail-out procedures (RR-47.1;p&lt;0.001) post-operative complications (RR-11.9;p&lt;0.001), re-admission (RR-2.4;p&lt;0.001) and post-operative imaging/intervention (RR6.5;p&lt;0.001). Variables associated with PPS included ag ≥ 60 (OR-1.56;p=0.011), male sex (OR-1.47;p=0.022), ASA 2 (OR-1.63;p=0.019, ASA≥3 (OR-3.27;p&lt;0.001), 2 hospital admissions (OR-1.56;p=0.046), ≥3 hospital admissions (OR-2.11;p=0.024), cholecystitis (OR-3.19;p&lt;0.001), pre-operative ERCP (OR-3.49;p&lt;0.001) and cholecystostomy (OR-2.77;p=0.025) and emergency LC (OR-5.20;p&lt;0.001). The AUC (area under curve) for the derivation and validation cohorts were 0.83 and 0.81 respectively. The risks of PPS in low-risk (0-5), medium-risk (5.5-10) and high-risk (&gt;10) groups were 3.3%, 14.9% and 45.1%, respectively. 

Conclusions

The rate of PPS following LC is significant and strongly associated with peri- and post-operative morbidity. Our model concludes that multiple pre-operative patient factors can predict the likelihood of prolonged post-operative stay. A patient’s risk score could be used to assess the risk of morbidity. Pragmatic patient selection in accordance with the above model could help surgical centres improve the allocation of beds between tertiary centres and day-surgery units. 

P-BN61 Optimal timing of laparoscopic cholecystectomy for admitted acute cholecystitis patients

Background

The Tokyo 2018 guidelines support emergency laparoscopic cholecystectomy (ELC) for acute cholecystitis (AC) over delayed laparoscopic cholecystectomy (DLC) for mild cholecystitis, substantiated by a lower total length of stay. The supporting studies are limited by small sample sizes, and clinically relevant findings may have been missed. The aims of the present paper were firstly, to compare the peri- and post-operative course following emergency and delayed LC for AC.

Methods

All patients who underwent ELC and DLC for AC following hospital admission between January 2015 and December 2019 were included in the study. Pre-operative, operative and post-operative data over a 100-day follow-up period were collected retrospectively from multiple databases using a deterministic records-linkage methodology. Patients were splint into groups based on previous admissions and outcomes were compared between ELC and DLC. Multivariate logistic regression models were then used on the entire cohort to adjust for other variables and to determine the impact of ELC versus DLC. Complications of the category Clavien-Dindo ≥2 were considered.

Results

In the group with no previous admissions (n = 630), DCL patients had lower rates of intra-/post-operative complications (8.0%vs.17.9%;p&lt;0.001), lower rates of re-admission (6.6%vs.12.2%;p=0.04) and longer total length of stay (6dvs.5d;p=0.03). In patients with previous admissions (n = 181), DCL had lower rates of intra-/post-operative complications (14.1%vs.25.5%;p=0.06) but there was no significant difference in length of stay (13dvs.12d;p=0.81). The ELC group had a significantly lower admission CRP, ASA and age (p &lt; 0.001). In the multivariate logistic regression models, ELC was positively associated with subtotal/conversion to open (OR,1.94;p=0.01), drain insertion (OR,2.54;p&lt;0.001), bile leak (OR,2.38;p&lt;0.001), post-operative imaging (OR,1.83;p=0.01), longer post-operative stay (OR,7.26,p&lt;0.001) and readmission (OR-1.9;p=0.01). 

Conclusions

DLC, once the period of active inflammation has settled, offers superior post-operative outcomes, including lower rates of complication, re-admission and post-operative length of stay; however is associated with longer total length of stay. DLC is only advised where the risk of re-admission is minimised (i.e surgery six weeks following the episode) and relies on the management of surgical waiting lists.

Improving day surgery rates of anterior cruciate ligament reconstruction surgery in surgical units not dedicated to performing day surgery: A retrospective observational cohort study

BACKGROUND AND AIMS

Current guidance advises that at least 90% of anterior cruciate ligament reconstructions are performed as day-case operations. Same-day surgery rates achieved by surgical units have significant clinical and financial implications. The primary aim of this multi-centre study was to determine the rate of admission and causes for admissions in patients undergoing anterior cruciate ligament reconstruction.

METHOD

Patient documentations were studied for those who underwent an elective anterior cruciate ligament reconstruction between January 2015 and April 2019. Contributing factors related to admission length were investigated and included patient age, gender, body mass index (BMI), operating surgeon, operating hospital, American Society of Anaesthesiology (ASA) grade, and position of the patient on the operating list. Both univariate and multivariate analysis were conducted using the STATA/IC 16.1 statistical package.

RESULTS

The day surgery rate of anterior cruciate ligament reconstructions were 52% (50/95). Patients positioned later on the operating list were more likely to be admitted post-operatively (OR, 4.49; P = .002; 95% CI, 1.72-11.69) and this was the only factor associated with admission. A large majority of admitted patients (95.6%) were admitted without a clinical cause and were otherwise safe for same-day discharge.

CONCLUSIONS

The day surgery rate for ACL reconstruction remains low, despite an extremely low complication rate. Reconfiguration of the operating lists and positioning anterior cruciate ligament reconstructions earlier in the day will likely increase the same-day discharge rate and reduce associated costs.

SP4.1.13 Management of appendicitis during COVID-19 pandemic; short-term outcomes

Aims

COVID-19 pandemic has predisposed patients undergoing surgery to post-operative infection and resultant complications. Appendicitis is frequently managed by appendicectomy. After the onset of the pandemic, selected cases of appendicitis were managed with antibiotics which is a recognised treatment option. Our objective was to compare the management of appendicitis and post-operative outcomes between pre- and post-COVID-19.

Methods

Ninety-six patients were identified from before the onset of the pandemic (November 2019) to after the onset of the pandemic (May 2020). Data were collected retrospectively from electronic records including demographics, investigations, treatment, duration of inpatient stay, complications, readmissions and compared between pre- and post-COVID-19 groups.

Results

One hundred percent underwent surgical treatment before the onset of pandemic, compared with 56.3% from the onset of the pandemic. A greater percentage of patients were investigated with imaging post-COVID-19 (100% versus 60.9%; p < 0.00001). There was no significant difference in the outcomes between the two groups.

Conclusion

CT/MRI scan was preferred to laparoscopy in diagnosing appendicitis and conservative management of uncomplicated appendicitis was common practice after the onset of pandemic. Health boards can adapt their management of surgical conditions during pandemics without adverse short-term consequences. Long term follow-up of this cohort will identify patients suitable for conservative management.

TP6.2.5 Post-operative recovery following emergency laparoscopic cholecystectomy: a need to redefine the consent for emergency cholecystectomy

Aims

Understanding the risks of emergency LC is necessary before patients can make an informed decision regarding operative management. Our primary aim was to provide a comprehensive analysis of the post-operative course of these patients.

Methods

Emergency LC performed for all biliary pathology across three surgical units between January 2015 and January 2020 were included. We followed each patient up for 100 days postoperatively and data was collected retrospectively. Data collected included demographic data, operative data, post-operative recovery, imaging, additional interventions and re-admissions.

Results

A total of 605 patients were identified (median age, 53 years (range 13-92); M:F, 1:2.7). 36.9% of patients had a complicated postoperative period, either suffering a significant complication, requiring prolonged post-operative stay (&gt;3 days), further imaging, additional interventions or re-admission. The rate of complication was 13.5% (including retained stones 3.5%; collections 3.8%; bile leaks 3.3%). The rate of prolonged post-operative stay was 25.1%. 16.2% required postoperative imaging and 6.1% required post-operative intervention.12.9% were re-admitted for assessment related to the LC. The rate of bile duct injury was 0% (0/605).

Conclusions

Although LC has the reputation of largely an uncomplicated procedure, our data illustrates the substantive morbidity associated with emergency LC. Patients should be counselled about the high morbidity rates. This involves patient education and will improve consent which should help decrease litigation. Surgeons should take a more selective and pragmatic approach when offering the procedure.

TP6.1.9 Prolonged post-operative stay following emergency and elective laparoscopic cholecystectomies and its contributing factors

Aims

Patients who undergo laparoscopic cholecystectomy (LC) for gallstone disease are a heterogenous population with many variables involved in their management. The aim was to identify the proportion of patients who have a prolonged post-operative stay (PPS; &gt;3days) following elective and emergency LC and the variables that most contribute to PPS.

Methods

We retrospectively collected data for all patients who underwent an elective and emergency LC across three surgical units from 2015 to 2020. Rates of PPS were compared between elective and emergency groups and variables associated with PPS were identified using multivariate logistic regression models.

Results

2769 patients were included in the study (median age, 53years(range, 13-92); M:F,1:2.7; emergency:elective,1:3.6) The rate of PPS was higher in the emergency versus elective group (25.1% versus 6.6%; p&lt;0.0001). Pain was one of the major causes in both groups. In the elective group, factors associated with PPS included cholecystitis (OR,1.96; p=0.008), previous gallstone related admissions (OR,1.48; p=0.008), pre-operative ERCP (OR,3.58;p&lt;0.0001), ASA (OR,1.82; p=0.001) and age (years) (OR,1.03;p=0.001). In the emergency group, factors associated with PPS include cholecystitis (OR,5.3;p&lt;0.0001), ASA (OR,1.96; p = 0.01) and pre-operative ERCP (OR,4.44;p=0.001).

Conclusions

The rate of PPS following laparoscopic cholecystectomy is significant, particularly in the emergency group. Although the possibility of PPS cannot be avoided, patient information regarding the possibility of PPS is important, particularly for those at risk. The risk factors for PPS should be used to guide surgical decision making and should be followed by targeted management of these patients including optimised pain relief.

EP.TU.688The fate of the rectal stump following subtotal colectomy for acute colitis

Aims

Acute severe colitis requires surgery in approximately thirty percent of cases. Subtotal colectomy with end ileostomy is the standard procedure with distinct advantages to a laparoscopic approach. Controversy surrounds the optimal short and long-term management of the distal rectal stump. This study reviews the clinical outcomes and the fate of the rectal stump in this patient cohort.

Methods

Analysis of prospective data of patients who underwent emergency subtotal colectomy for severe acute colitis between 2010 and 2020 in a tertiary referral centre.

Results

Sixty-six patients underwent subtotal colectomy (median age, 40years; M:F, 1.3:1). Subtotal colectomy was performed for failure of medical therapy during an acute episode of severe colitis (56%), for fulminant colitis (40%), or for colonic strictures (4%). In 98% percent of patients the rectal stump was closed at the level of the recto-sigmoid junction and in 2% a mucous fistula was formed. 73% of patients opted for no further surgery, but 27% underwent a completion proctectomy, most commonly performed because of rectal stump bleeding. The median follow-up was 6.25years, during which 17% of those with a completion proctectomy underwent an ileo-pouch anal anastomosis (IPAA).

Conclusions

Subtotal colectomy with closed rectal intra-peritoneal stump and end ileostomy is the procedure of choice in severe acute colitis refractory to maximal medical therapy or fulminant colitis. Given the patient dissatisfaction and morbidity associated with mucous fistula, this procedure should be abandoned. Pelvic dissection should not be performed at the time of the emergency subtotal colectomy given the risk of morbidity.

Does non-visible haematuria require urgent assessment? A retrospective cohort study from a university teaching hospital

OBJECTIVES

It is not certain from current evidence which patient groups with non-visible haematuria (NVH) require urgent investigation and which investigations are sufficient. We report referral outcomes data from Scotland to identify patient groups who will benefit from urgent assessment to rule out urological cancer (UC) and whether full set of investigations are necessary in all referred patients.

MATERIALS AND METHODS

Data were collected from electronic patient records for patients referred with NVH to secondary care urology services between July 2017 and May 2020. The correlations between risk factors and final diagnosis were assessed using categorical variables in a multivariate logistic regression analysis and using chi-squared models. Statistical analysis was performed using IBM SPSS data editor version 25.

RESULTS

Our study cohort comprised 525 patients (43.4% males; median age 66 years), in which UC was diagnosed in 25 patients (4.8%). Age > 60 years had sensitivity and NPV for UC of 92% and 99%, respectively. Univariate and multivariate analysis showed male sex, age ≥ 60 years and smoking were significant predictors of UC in patients with NVH (p < 0.05). There was no significant difference in UC in patients with history of LUTS, anticoagulation and previous UC.

CONCLUSION

The risk of urologic cancer in NVH patients is significant and male gender, age ≥ 60 years and smoking are significant predictors of UC. Patients with risk factors of UC require complete assessment of both the upper and lower urinary tract; however, in the absence of risk factors, patients do not require urgent or complete assessment.

Complex Renal Cysts (Bosniak ≥ IIF): Outcomes in a Population-Based Cohort Study

Simple Summary

Researchers from the University of Dundee have found that not all kidney cancers will need urgent surgery. In a published research in the Cancers, Dr Lucocq et al have carefully established database record of patients with kidney cancer looking like water filled sacs on CT scan and reported that these cancers are low grade and perhaps less harmful on long-term follow-up. In fact, behaviour of these cancer cells is much slower compared to other diseases such as heart failure and high blood pressure. Most people die from chronic disease much before cancer spread or progression. The researchers in this group have shown that surgical removal of these cancers, particularly in elderly people and those with other health conditions such as heart failure may not be necessary. Patients in Tayside Urological Cancers (TUCAN) database were carefully assessed using CT scans and discussed in multidisciplinary meetings and were followed up for more than 6 years. This kind of population-based study adds new knowledge to the understanding behaviour of a subset kidney cancers which otherwise have very poor outcome. The researchers and paper highlight careful documentation of cohort to understand natural history of disease.

Abstract

There is emerging evidence to suggest that con-current medical conditions influence the outcome of cancers, irrespective of therapy offered. The prevalence and impact of co-morbidities on the survival outcome of complex renal cystic masses in not known. The objective was to study complex renal cysts (Bosniak ≥IIF ) and assess the overall and renal cancer-specific survival in a population-based database including impact of con-current morbidities. The Tayside Urological Cancer Network (TUCAN) database covering a stable population of more than 416,090 inhabitants in a defined geographical area identified 452 complex renal cysts in 415 patients between 2009 and 2019. Each patient was tracked and followed up using a unique identifier and deterministic linkage methodology. The last date of follow-up including cause of death was determined. Co-morbidities were recorded from primary care referrals. Renal cancer-specific mortality was 1.7% at a median follow-up of 76.0 months; however, overall survival was poor, particularly in patients ≥ 70 years of age and with ≥ 2 significant co-morbid conditions (p < 0.0001). A total of 38.3% of the cohort showed con-current morbidities. Age and co-morbidities were significant risk factors for overall survival in patients with complex renal cystic disease and a careful assessment should be made to recommend surgical intervention in the elderly population, in particular in those with other health-related conditions.

Management of appendicitis during COVID-19 pandemic; short-term outcomes

Background and aim

COVID-19 pandemic has predisposed patients undergoing surgery to post-operative infection and resultant complications. Appendicitis is frequently managed by appendicectomy. After the onset of the pandemic, selected cases of appendicitis were managed with antibiotics which is a recognised treatment option. Our objective was to compare the management of appendicitis and post-operative outcomes between pre- and post-COVID-19.

Methods

Ninety-six patients were identified from before the onset of the pandemic (November 2019) to after the onset of the pandemic (May 2020). Data were collected retrospectively from electronic records including demographics, investigations, treatment, duration of inpatient stay, complications, readmissions and compared between pre- and post-COVID-19 groups.

Results

One hundred percent underwent surgical treatment before the onset of pandemic, compared with 56.3% from the onset of the pandemic. A greater percentage of patients were investigated with imaging post-COVID-19 (100% versus 60.9%; p < 0.00001). There was no significant difference in the outcomes between the two groups.

Conclusion

CT/MRI scan was preferred to laparoscopy in diagnosing appendicitis and conservative management of uncomplicated appendicitis was common practice after the onset of pandemic. Health boards can adapt their management of surgical conditions during pandemics without adverse short-term consequences. Long term follow-up of this cohort will identify patients suitable for conservative management.

Complex renal cysts (Bosniak ≥IIF): interobserver agreement, progression and malignancy rates

Objective

The objective was to assess the interobserver agreement rate, progression rates and malignancy rates in the assessment of complex renal cysts (≥ Bosniak IIF) using a population-based database.

Methods

A regional database identified 452 complex renal cysts in 415 patients between 2009 and 2019. Each patient was tracked and followed up using a unique identifier and deterministic linkage methodology. The interobserver agreement rate between radiologists was calculated using a weighted kappa statistic. Progression and malignancy rates of cysts (Bosniak ≥IIF) over the 11-year period were calculated.

Results

The linear-weighted kappa value was 0.69 for all complex cysts. The rate of progression and regression of Bosniak IIF cysts was 4.6% (7/151) and 3.3% (5/151), respectively. All malignant IIF cysts progressed within 16 months of diagnosis. The malignancy rate of surgically resected Bosniak III and IV cysts was 79.3% (23/29) and 84.5% (39/46), respectively. Of all malignant tumours, 73.8% and 93.7% were of low ISUP grade and low stage, respectively.

Conclusions

This study further confirms that there is a good degree of agreement between radiologists in classifying complex renal masses using the Bosniak classification. The progression rate of Bosniak IIF cysts is low, but the malignancy rates of surgically resected Bosniak IIF, III and IV cysts are high. Benign cysts are frequently resected, and a very high proportion of histopathologically confirmed cancers in complex renal cysts are of low grade and stage.

Key Points

•There is a good degree of agreement between radiologists in classifying complex renal masses using the Bosniak classification.

•The rate of progression of Bosniak IIF cysts is low, and malignant cysts progress early during surveillance. Although the malignancy rates of resected Bosniak IIF, III and IV cysts are high, the rate of benign cyst resection is significant.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-07186-w) contains supplementary material, which is available to authorized users.

The immunofluorescent era of membrane traffic

In recent years immunofluorescence microscopy has been increasingly used to study membrane traffic. In this article seven electron microscopists, all with considerable experience in using light microscopy, take a critical look at the immunofluorescence approach and argue that results obtained with this method are often overinterpreted.

Evidence for prebudding arrest of ER export in animal cell mitosis and its role in generating Golgi partitioning intermediates

During mitosis the interconnected Golgi complex of animal cells breaks down to produce both finely dispersed elements and discrete vesiculotubular structures. The endoplasmic reticulum (ER) plays a controversial role in generating these partitioning intermediates and here we highlight the importance of mitotic ER export arrest in this process. We show that experimental inhibition of ER export (by microinjecting dominant negative Sar1 mutant proteins) is sufficient to induce and maintain transformation of Golgi cisternae to vesiculotubular remnants during interphase and telophase, respectively. We also show that buds on the ER, ER exit sites and COPII vesicles are markedly depleted in mitotic cells and COPII components Sec23p, Sec24p, Sec13p and Sec31p redistribute into the cytosol, indicating ER export is inhibited at an early stage. Finally, we find a markedly uneven distribution of Golgi residents over residual exit sites of metaphase cells, consistent with tubulovesicular Golgi remnants arising by fragmentation rather than redistribution via the ER. Together, these results suggest selective recycling of Golgi residents, combined with prebudding cessation of ER export, induces transformation of Golgi cisternae to vesiculotubular remnants in mitotic cells. The vesiculotubular Golgi remnants, containing populations of slow or nonrecycling Golgi components, arise by fragmentation of a depleted Golgi ribbon independently from the ER.

Immunolocalisation of phospholipase D1 on tubular vesicular membranes of endocytic and secretory origin

We have examined the localisation of overexpressed phospholipase D1 (PLD1) using antibodies against its amino- and carboxyl-terminal domains. PLD1 overexpressed in COS-7 cells showed variable distribution by immunofluorescence but was mainly in punctate structures in the perinuclear region and at the plasma membrane. Downregulation by an anti-sense plasmid resulted in almost exclusively perinuclear distribution in punctate structures that contained immunoreactivity for the endogenous KDEL receptor and the early endosomal antigen EEA1 protein. Influenza haemagglutinin (HA) and HA-derived mutants designed to locate primarily to secretory or endocytic membranes were present in PLD1-positive membranes. Immunofluorescence analysis in permanent CHO cell lines that express PLD1 inducibly confirmed the presence of PLD1 on both endocytic and secretory membranes. Analysis of PLD1 distribution by immunocytochemistry and electron microscopy of intact CHO cells and of isolated membranes revealed that PLD1 was present in tubulovesicular elements and multivesicular bodies. Some of these were close to the Golgi region whereas others stained positive for endocytic cargo proteins. Morphometric analysis assigned the majority of PLD1 immunoreactivity on endosomal membranes and a smaller amount on membranes of secretory origin. PLD1, via signals that are currently not understood, is capable of localising in tubulovesicular membranes of both endocytic and secretory origin.

Merkel cells in the human oesophagus

Merkel cells (MCs) are well recognized in the basal layers of the skin and oral mucosa, but this paper describes for the first time the presence of MCs in the human oesophagus. These cells are not identified in neonatal oesophagus, but are seen singly and in clusters in adult specimens. Application of stereological techniques shows that MCs are more numerous in the mid-oesophageal region. Cells expressing established markers of MCs have also been demonstrated in two out of six primary small cell carcinomas of the oesophagus. Further investigation of the role of MCs in oesophageal innervation and epithelial biology will be of interest.

Role of phosphatidylinositol 3,4,5-trisphosphate in regulating the activity and localization of 3-phosphoinositide-dependent protein kinase-1

3-Phosphoinositide-dependent protein kinase-1 (PDK1) interacts stereoselectively with the d-enantiomer of PtdIns(3,4,5)P3 (KD 1.6 nM) and PtdIns(3,4)P2 (KD 5.2 nM), but binds with lower affinity to PtdIns3P or PtdIns(4,5)P2. The binding of PtdIns(3,4,5)P3 to PDK1 was greatly decreased by making specific mutations in the pleckstrin homology (PH) domain of PDK1 or by deleting it. The same mutations also greatly decreased the rate at which PDK1 activated protein kinase Balpha (PKBalpha) in vitro in the presence of lipid vesicles containing PtdIns(3,4,5)P3, but did not affect the rate at which PDK1 activated a PKBalpha mutant lacking the PH domain in the absence of PtdIns(3,4,5)P3. When overexpressed in 293 or PAE cells, PDK1 was located at the plasma membrane and in the cytosol, but was excluded from the nucleus. Mutations that disrupted the interaction of PtdIns(3,4,5)P3 or PtdIns(4,5)P2 with PDK1 abolished the association of PDK1 with the plasma membrane. Growth-factor stimulation promoted the translocation of transfected PKBalpha to the plasma membrane, but had no effect on the subcellular distribution of PDK1 as judged by immunoelectron microscopy of fixed cells. This conclusion was also supported by confocal microscopy of green fluorescent protein-PDK1 in live cells. These results, together with previous observations, indicate that PtdIns(3,4,5)P3 plays several roles in the PDK1-induced activation of PKBalpha. First, it binds to the PH domain of PKB, altering its conformation so that it can be activated by PDK1. Secondly, interaction with PtdIns(3,4,5)P3 recruits PKB to the plasma membrane with which PDK1 is localized constitutively by virtue of its much stronger interaction with PtdIns(3,4,5)P3 or PtdIns(4,5)P2. Thirdly, the interaction of PDK1 with PtdIns(3,4,5)P3 facilitates the rate at which it can activate PKB.

Quantitative immunoelectron microscopy reveals alpha2,6 sialyltransferase is concentrated in the central cisternae of rat hepatocyte Golgi apparatus

The Golgi apparatus is a membrane bound organelle involved in synthesis of N-linked oligosaccharides which are trimmed and then lengthened by a series of sugar transferases adding N-acetylglucosamine, galactose and sialic acid in sequence. We previously published qualitative work which localized Galbeta1,4GlcNAc alpha2,6 sialyltransferase of rat hepatocytes to the trans cisternae and the trans Golgi network. We now report the use of combined stereological and immunoelectron microscopical techniques for mapping the Golgi stack composition and distribution of sialyltransferase protein in rat hepatocytes. The Golgi stack showed substantial variation in composition consisting of 1, 2, 3, 4, or 5 cisternae with an average of 2.5 cisternae. Sialyltransferase labeling was mainly located in the central cisternae of the Golgi stacks irrespective of whether the stacks were oriented in a cis/trans direction using morphological criteria. Only 20% of the total sialyltransferase labeling was present in the transmost cisterna and 2% in the trans Golgi Network. The low labeling in the transmost cisterna was essentially due to the presence of a sialyltransferase negative cisterna. These data emphasize the importance of quantitation in obtaining a representative picture of Golgi enzyme distribution in three dimensions. They indicate that central cisternae, rather than the transmost cisterna and TGN, function in sialylation along the secretory pathway of rat hepatocytes.

ERK2 signalling from internalised epidermal growth factor receptor in broken A431 cells

Activation of extracellular signal-regulated kinase 2 (ERK2) signalling from epidermal growth factor receptors (EGFRs) is widely assumed to originate in the plasma membrane. Using an in vitro assay, we investigated whether EGF/EGFR complexes internalised by endocytosis in A431 cells can initiate signalling in the ERK2 pathway. At 0 degrees C, binding of EGF induced tyrosine phosphorlyation of EGFR and, when the cells were subsequently broken by scraping and warmed in the presence of exogenous cytosol, activation of ERK2 occurred. At 0 degrees C, washes with pH 4.5 media reversed EGF binding, tyrosine phosphorylation and ERK-2 activation in exogenous cytosol, providing conditions in which signalling from the cell surface and internalised EGFRs could be distinguished. When cells containing internalised EGF/EGFR complexes were first washed in low pH media at 0 degrees C and then broken and incubated in exogenous cytosol, substantial activation of ERK2 occurred. This activation reached a maximum after a 5-min internalisation and was almost completely prevented by incubation in 0.45 M sucrose, a known inhibitor of receptor-mediated endocytosis. These data are consistent with activation of the ERK2 signalling pathway by internalised EGRFs situated in endosomal compartments. Our observation that EGFR tyrosine dephosphorylation is incomplete above pH 5.5 suggests that signalling is initiated in early endosomes.

Evidence for fusion between multilamellar endosomes and autophagosomes in HeLa cells

The organelles of the endocytic and autophagic pathways were studied in HeLa cells using immunoelectron microscopy and stereological techniques. In the absence of autophagic stimulation, characteristic particulate structures containing closely packed layers of membrane received the fluid-phase marker horseradish peroxidase after 25 min uptake. These multilamellar endosomes contained the majority of the cellular immunogold labeling obtained by using a monoclonal antibody (1B5) directed against a lysosomal glycoprotein. Lysosomes with homogeneous dense content were only poorly labeled. After stimulation of autophagy, two classes of autophagosome profile appeared. One had a double limiting membrane and content that resembled the surrounding cytoplasm. The other most abundant type possessed a single limiting membrane and contained multilamellar structures which were strikingly similar to multilamellar endosomes, not only in form, but also in volume and membrane packing density. Immunogold labeling showed that now the majority of 1B5 labeling was located in the class of autophagosomes which contained multilamellar structures. Stereological methods showed that, after autophagic stimulation, multilamellar endosomes had become depleted, while multilamellar structures had appeared within the autophagosomes. Taken together, these data provide evidence that autophagosomes of HeLa cells fuse with preexisting multilamellar endosomes.

Selective adsorption: a new method for purification of protein A-gold complexes

Protein gold complexes are prepared by adding gold colloids to cytochemically active proteins in solution. The gold particles of the colloid form complexes with the protein spontaneously, but some of the protein remains uncomplexed. Currently, when protein A-gold complexes are prepared, the uncomplexed protein. A is separated from the complex by ultracentrifugation, which is a lengthy procedure and requires special equipment. This report describes a simple and rapid method for removing uncomplexed protein A from freshly-prepared "crude" protein A-gold at the laboratory bench. In this method, larger gold particles of 15-nm diameter are added to a crude protein A-gold preparation made with smaller particles (e.g.,6nm diameter). The 15-nm particles adsorb uncomplexed protein A preferentially, but do not form complexes with already-formed 6-nm protein A-gold. The adsorbed protein A, attached to the 15-nm particles, can then be sedimented in a bench centrifuge, leaving the purified 6-nm protein A-gold complexes in the supernatant. The stability, immunocytochemical activity, and degree of aggregation of the protein A-gold complexes prepared by this method are comparable to protein A-gold complexes prepared by ultracentrifugation. The method is simple to perform, avoids lengthy purification procedures, and yields complexes with reproducible labelling characteristics.

The pathway of Golgi cluster formation in okadaic acid-treated cells

Using stereology and immunoelectron microscopy we examined the pathway of Golgi cluster formation during treatment with the phosphatase inhibitor okadaic acid. During the first hour the Golgi stack of suspension HeLa cells lost 90% of its membrane without appreciable reduction in the number of cisternae. During this time clusters of tubules and vesicles (Golgi clusters) appeared and these contained only a fraction of the Golgi membrane present in untreated cells. Despite the overall reduction in membrane the total amount of immunolabeling for galactosyltransferase over the Golgi clusters of a typical cell was maintained, indicating that galactosyltransferase had been retained in Golgi membranes. The observation that, after 40 min okadaic acid treatment, labeling density for galactosyltransferase within trans Golgi cisternae increased 1.6-fold (n = 3, CE 10%) suggests that membrane loss from trans cisternae was selective. Careful evaluation of immunolabeled clusters showed that most of the galactosyltransferase labeling was located over complex tubular profiles and not vesicular profiles. Tubular structures were also observed during disassembly and these were found both connected to disassembling cisternae and within forming Golgi clusters, indicating that they were intermediates in cluster formation. We also investigated the role of vesicular transport in cluster formation. During disassembly we found no accumulation of COP-coated buds and vesicles over Golgi membrane. However, aluminium fluoride, previously found to arrest transport in the Golgi stack, completely inhibited membrane depletion and stack disassembly. Taken together, our results indicate that during Golgi cluster formation, membrane leaves the Golgi but galactosyltransferase is retained within a tubular reticulum which is a direct descendant of trans-Golgi cisternae. Membrane depletion may require ongoing vesicular transport and we postulate that it arises because of an imbalance in membrane traffic into and out of the Golgi apparatus.

Quantitation of gold labelling and antigens in immunolabelled ultrathin sections

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