Incidence of deep vein thrombosis after colorectal surgery in a Chinese population

Venous Thromboembolism Following Major Abdominal Surgery for Cancer: A Guide for the Surgical Intern

BACKGROUND

Venous thromboembolism (VTE) is a term used to compositely describe deep vein thrombosis (DVT) and pulmonary embolism (PE). Overall, the incidence of VTE after major abdominal and pelvic surgery has been reported to be between 10% and 40%.

OBJECTIVE

To estimate the incidence of post-operative VTE in patients undergoing major abdominal surgery for cancer, to identify risk factors associated with VTE, and to assess available thromboprophylaxis tools.

METHODS

A Medline and Cochrane literature search from database inception until February 1st, 2021 was performed according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines.

RESULTS

Thirty-one studies met our eligibility criteria and were included in the current review. In total, 435,492 patients were identified and the overall incidence of VTE was 2.19%( 95% CI: 1.82-2.38). Τhe following risk factors were associated with VTE: smoking, advanced age (>70 years), a history of diabetes mellitus, American Society of Anesthesiologists' (ASA) classification of Physical Health class III or IV, a history of cardiovascular or pulmonary disease, a history of DVT or PE, elevated plasma fibrinogen level, c-reactive protein (CRP) level, cancer stage III or IV, postoperative acute respiratory distress syndrome (ARDS), prolonged postoperative hospital stay, previous steroid use, history of Inflammatory Bowel Disease (IBD), heart failure and neoadjuvant and adjuvant chemotherapy.

CONCLUSION

VTE remains an important complication after major abdominal surgery for cancer and seems to increase mortality rates.

Efficacy and safety of anticoagulant prophylaxis for prevention of postoperative venous thromboembolism in Japanese patients undergoing laparoscopic colorectal cancer surgery

AIM

To investigate the efficacy and safety of anticoagulant prophylaxis to prevent postoperative venous thromboembolism (VTE) during laparoscopic colorectal cancer (CRC) surgery, which is unknown in Japanese patients.

METHODS

We conducted this randomized controlled trial at nine institutions in Japan from 2011 to 2015. It included 302 eligible patients aged 20 years or older who underwent elective laparoscopic surgery for CRC. Patients were randomly assigned to an intermittent pneumatic compression (IPC) therapy group or to an IPC + anticoagulation therapy group. Anticoagulation therapy comprised fondaparinux or enoxaparin for postoperative VTE prophylaxis. Postoperative VTE was diagnosed based on enhanced multi-detector helical computed tomography. The primary endpoint was VTE incidence, including asymptomatic cases, the secondary endpoint was incidence of major bleeding, and we conducted an intention-to-treat analysis. This study is registered in UMINCTR (UMIN000008435).

RESULTS

Postoperative VTE incidence was 5.10% with IPC therapy (n = 157) and 2.76% with IPC + anticoagulant therapy (n = 145; P = .293). We identified no symptomatic VTE cases. The major bleeding rates were 1.27% with IPC alone and 1.38% with the combination (P = .936). The overall bleeding rates were 7.69% for enoxaparin and 13.6% for fondaparinux (P = .500), and there were no bleeding-related deaths.

CONCLUSION

Anticoagulant prophylaxis did not reduce the incidence of VTE and the incidence of major bleeding was comparable between the two groups. Usefulness of perioperative anticoagulation was not demonstrated in this study. Pharmacological prophylaxis must be restricted in Japanese patients with higher risk of VTE.

Incidence, risk factors, and outcomes of venous thromboembolism after oncologic surgery: A systematic review and meta-analysis

BACKGROUND

The risk and prognosis of VTE associated with oncologic surgery need to be quantified to guide patient management. We aimed to examine the availability of data and to report the incidence of venous thromboembolism (VTE) in cancer patients after surgery, as well as the clinical outcomes of VTE following oncologic surgery.

METHODS

We searched multiple databases for terms related to VTE after oncologic surgery from inception to November 1, 2017. A random-effects meta-analysis was done to calculate the pooled incidence of VTE.

RESULTS

Of the 8611 citations identified, 136 studies including 1,481,659 patients met the eligibility criteria. The overall incidence of VTE was estimated to be 2.3% (95% CI 2.1-2.5). Bone and soft tissue cancer (10.6%, 95% CI 2.9-18.2) and lung cancer (8.1%, 95% CI 3.7-12.6) were associated with the highest and second highest risk of postoperative VTE, respectively. Age (standardized mean difference [SMD] = 0.46, 95% CI 0.40-0.53; I² = 93.8%), radiation (OR 1.29, 95% CI 1.03-1.62; I² = 34.6%), transfusion (OR 1.96, 95% CI 1.48-2.59; I² = 57.0%), and operative time (SMD = 1.12, 95% CI 1.07-1.16; I² = 100%) were possible risk factors for postoperative VTE. Patients with VTE versus those without had increased odds of all-cause fatal events (11.15, 95% CI 4.07-30.56; I² = 92.0%).

CONCLUSIONS

The risk of VTE after oncologic surgery remains high, and this risk varied according to the cancer type, study region, surgical location, and thromboprophylactic strategy. VTE is associated with increased mortality at the early stage of cancer surgery.

Prospective implementation of a standardized screening protocol for deep venous thrombosis in abdominal surgical oncology patients

BACKGROUND AND OBJECTIVES

Venous thromboembolism (VTE) remains a major cause of perioperative morbidity and mortality despite implementation of prophylaxis guidelines. We sought to identify risk factors for occult deep venous thrombosis (DVT) following abdominal surgery for cancer and measure the clinical impact of a prospectively implemented standardized postoperative DVT screening protocol.

METHODS

Patients undergoing abdominal surgery for malignant indication were screened with early postoperative lower extremity duplex to identify DVT. Clinical and pathologic factors associated with DVT were identified.

RESULTS

Among 255 patients meeting study criteria, 25 (9.8%) had occult lower extremity DVT on routine postoperative screening. Prior history of VTE and lower preoperative hemoglobin were independently associated with DVT (OR, 9.05; P = 0.004; and OR, 1.27; P = 0.025, respectively). Preoperative chemotherapy within 1 year and thrombocytopenia were associated with DVT in univariate analyses only. Five patients developed postoperative pulmonary emboli (2.0%); three following negative duplex and two following positive duplex for distal DVT for which the patients were not therapeutically anticoagulated due to a contraindication. There were no pulmonary emboli in duplex-positive patients who were anticoagulated or who had vena cava filter placed.

CONCLUSION

Despite prophylaxis, the prevalence of occult DVT in abdominal oncologic surgery patients is considerable. Postoperative screening duplex can identify these events to guide management.

Prospective Study on the Incidence of Postoperative Venous Thromboembolism in Korean Patients with Colorectal Cancer

PURPOSE

Pharmacologic thromboprophylaxis is routinely recommended for Western cancer patients undergoing major surgery for prevention of venous thromboembolism (VTE). However, it is uncertainwhetherroutine administration of pharmacologic thromboprophylaxis is necessary in all Asian surgical cancer patients. This prospective study was conducted to examine the incidence of and risk factors for postoperative VTE in Korean colorectal cancer (CRC) patients undergoing major abdominal surgery.

MATERIALS AND METHODS

This study comprised two cohorts, and none of patients received perioperative pharmacologic thromboprophylaxis. In cohort A (n=400), patients were routinely screened for VTE using lower-extremity Doppler ultrasonography (DUS) on postoperative days 5-14. In cohort B (n=148), routine DUS was not performed, and imaging was only performed when there were symptoms or signs that were suspicious for VTE. The primary endpoint was the VTE incidence at 4 weeks postoperatively in cohort A.

RESULTS

The postoperative incidence of VTE was 3.0% (n=12) in cohort A. Among the 12 patients, eight had distal calf vein thromboses and one had symptomatic thrombosis. Age ≥ 70 years (odds ratio [OR], 5.61), ≥ 2 comorbidities (OR, 13.42), and white blood cell counts of > 10,000/μL (OR, 17.43) were independent risk factors for postoperative VTE (p < 0.05). In cohort B, there was one case of VTE (0.7%).

CONCLUSION

The postoperative incidence of VTE, which included asymptomatic cases, was 3.0% in Korean CRC patients who did not receive pharmacologic thromboprophylaxis. Perioperative pharmacologic thromboprophylaxis should be administered to Asian CRC patients on a risk-stratified basis.

Incidence of venous thromboembolism and its pharmacological prophylaxis in Asian general surgery patients: a systematic review

BACKGROUND

Venous thromboembolism (VTE) is a condition that has always been perceived to be rare in Asia. The aim of this systematic review was to gather the current available evidence on the incidence of VTE in this population. A secondary aim was to assess the efficacy of pharmacological prophylaxis, and hence determine its role, in the Asian population.

METHODS

A comprehensive literature search was performed using MEDLINE, Embase, and the Cochrane Database of Systematic Reviews in June 2014. Articles found using search terms related to venous thromboembolism (VTE), Asian countries and general surgery procedures and pathologies were screened using the following inclusion criteria: (1) either the population studied was primarily Asian or the study was conducted in an Asian country, (2) the subjects studied underwent a major gastrointestinal or other general surgery procedure, (3) the primary outcome was the incidence of deep vein thrombosis (DVT) or pulmonary embolus (PE), and (4) secondary outcomes assessed included mortality and complications due to the VTE or prophylaxis against VTE.

RESULTS

Fourteen publications with a total of 11,218 patients were analyzed. Nine of the fourteen were observational studies, with half being prospective in nature. There were five interventional studies of which two were randomized controlled trials. Among the observational studies, the median (range) incidence of above-knee DVT was 0.08 % (0-2.9 %), while the median (range) incidence of PE was 0.18 % (0-0.58 %). The rates of DVT in the control groups were reported to be between 0 and 7.4 %, while the incidence of PE in the control groups ranged from 0 to 1.9 %. Analysis of the comparative studies revealed that the incidence of bleeding-related complications varied from 0 to 18.1 % in the low-molecular-weight heparin (LMWH) group compared to 0-7.5 % in the control group. The difference in minor bleeding complications between the LMWH group and the control group was found to be statistically significant.

CONCLUSION

Data from this systematic review suggest that the risk of VTE in Asian general surgery patients is low, even in the context of risk factors typically regarded as high risk.

The rate and mortality of postoperative venous thromboembolism of moderate risk surgery in Asian patients without thrombo-prophylaxis: systematic review with meta-analysis

BACKGROUND

The general gynecologic and neurologic surgeries are regard as carrying moderate risk for postoperative venous thromboembolism (VTE). This review analyzed the postoperative VTE rate of these surgeries in Asia.

METHODS

Inclusion criteria were: prospective study; deep vein thrombosis (DVT) diagnosed by venography, ultrasonography, or radionucleotide scan; and no thromboprophylaxis. The pooled proportion was back calculated from Freeman-Tukey variant transformation, using a random effect model.

RESULTS

Medline, EMBASE, Cochrane Library, and KoreaMed were searched. Fourteen studies (total population of 1,625) published from 1974 to 2008 were included. In general surgery, the pooled rate of all-sites proximal, isolated distal DVT was 13.4, 2.1, and 11.8 % (radionucleotide scan). The cancer patients carried a higher all-sites DVT rate (19.7 % radionucleotide scan and 17.4 % ultrasound). Gynecologic and neurologic surgery had 3.1 % (ultrasound) and 3.8 % (radionucleotide scan) all-sites DVT rate. For general, gynecologic, and neurologic patients, the pooled rates of symptomatic DVT were 1.5, 0.2, and 1.0 % respectively. The pooled rate of symptomatic pulmonary embolism (PE) was 0.4 % for general surgery. No patients died from PE (pooled rate 0.2 %); however, a single PE death was reported in the excluded study.

CONCLUSIONS

Postoperative symptomatic VTE was relatively low in Asia. Further study is required to stratify VTE risk and the need for thromboprophylaxis in individual patients.

A randomized study on 1-week versus 4-week prophylaxis for venous thromboembolism after laparoscopic surgery for colorectal cancer. Ann Surg. 2014;259:665-669. [PMID: 24253138 DOI: 10.1097/sla.0000000000000340]

OBJECTIVE

To compare the efficacy and safety of antithrombotic prophylaxis given for 1 week or 4 weeks in patients undergoing laparoscopic surgery for colorectal cancer.

BACKGROUND

Extending antithrombotic prophylaxis beyond 1 week reduces the incidence of venous thromboembolism (VTE) after open abdominal surgery for cancer.

METHODS

In consecutive patients who underwent laparoscopic surgery for colorectal cancer, complete compression ultrasonography of the lower limbs was performed after 8 ± 2 days of antithrombotic prophylaxis. Patients with no evidence of VTE were randomized to short (heparin withdrawal) or to extended (heparin continued for 3 additional weeks) prophylaxis. Complete compression ultrasonography was repeated at day 28 ± 2 after surgery by investigators blinded to treatment allocation. The primary outcome of the study was the composite of symptomatic and ultrasonography-detected VTE at day 28 ± 2 after surgery.

RESULTS

Overall, 301 patients were evaluated for inclusion in the study and 225 were randomized. VTE occurred in 11 of 113 patients randomized to short (9.7%) and in none of the 112 patients randomized to extended heparin prophylaxis (P = 0.001). The incidence of VTE at 3 months was 9.7% and 0.9% in patients randomized to short or to extended heparin prophylaxis, respectively (relative risk reduction: 91%, 95% confidence interval: 30%-99%; P = 0.005). The rate of bleeding was similar in the 2 treatment groups. Two patients died during the study period, 1 in each treatment group.

CONCLUSIONS

After laparoscopic surgery for colorectal cancer, extended antithrombotic prophylaxis is safe and reduces the risk for VTE as compared with 1-week prophylaxis (NCT01589146).

Detection and Prevention of Post-Operative Deep Vein Thrombosis [DVT] Using Nadroparin Among Patients Undergoing Major Abdominal Operations in India; a Randomised Controlled Trial

Deep vein thrombosis [DVT] is one of the most dreaded complications in post-operative patients as it is associated with considerable morbidity and mortality. Majority of patients with postoperative DVT are asymptomatic. The pulmonary embolism, which is seen in 10% of the cases with proximal DVT, may be fatal. Therefore it becomes imperative to prevent DVT rather than to diagnose and treat. Only one randomized trial has been reported from India to assess the effectiveness of low molecular weight heparin in preventing post-operative DVT. To assess the risk of DVT in North Indian patients following major abdominal operations and to evaluate the effectiveness of Nadroparin, A Low Molecular Weight Heparin (LMWH) therapy in preventing post-operative DVT. Sixty five patients were randomised preoperatively into Group-I; Nadroparin prophylaxis and Group-II: No prophylaxis. The primary outcome was the occurrence of DVT, diagnosed by bilateral lower limb venogram performed, seven to ten days after operation. Secondary outcome measures included adverse effects of radio-opaque dye, intra-operative blood loss, operating time, postoperative platelet count, intraoperative blood transfusion requirements and the total duration of postoperative bed rest. No case of DVT occurred in either group. There was no statistical difference in the risk of secondary outcome measures in the two groups. DVT was not observed in any of the patients, even with several high risk factors indicating a possible protective mechanism in the North Indian population.

Deep venous thrombosis after surgery for inflammatory bowel disease: is standard dose low molecular weight heparin prophylaxis enough?

BACKGROUND

Inflammatory bowel disease (IBD) and colorectal surgery are risk factors for deep venous thrombosis (DVT). The aim of this prospective study was to evaluate the effectiveness of standardized prophylactic low molecular weight heparin (LMWH) therapy in patients who underwent surgery for ulcerative colitis (UC) and Crohn's disease (CD).

PATIENTS AND METHODS

Since 1999 all patients operated on for colorectal diseases in our institute have received 4,000 IU/day LMWH from the day of operation to discharge. The complete series of patients who had major colorectal surgery from 1999 until 2006 were reviewed for overt DVT episodes. Furthermore, 60 consecutive patients who were admitted for surgery for IBD were prospectively enrolled in the 2004-2006 period. Each patient underwent venous color Doppler ultrasound scan at admission and at discharge. Demographic data, disease activity, and clotting parameters were collected. Data were analyzed with Spearman's correlation test, multiple regression, and receiver operating characteristics (ROC) curves analysis.

RESULTS

The rate of DVT in UC patients was significantly higher than in colorectal cancer patients (p = 0.009), and the odds ratio (OR) for postoperative DVT in UC patients was 7.4 (95% CI 1.4-44.4; p = 0.017). Female gender, UC diagnosis, active rectal bleeding, aPTT value, aCL IgM, abeta2 IgM, and pANCA levels significantly correlated with postoperative DVT. At multivariate analysis only aCL IgM levels were found to be independently associated with postoperative DVT (p = 0.05).

CONCLUSIONS

In conclusion, our study showed that prophylactic therapy with 4,000 IU/day LMWH was not completely effective for the prevention of postoperative DVT in patients with CD, and even less so in those with UC. In these patients, a more tailored prophylactic therapy should be considered, and further randomized controlled trials testing the effectiveness of different prophylactic protocols would be advisable. Furthermore, aCL IgM serum levels might be helpful in identifying IBD patients who are at higher risk of postoperative DVT.

Does Prophylactic Subcutaneous Heparin Increase the Risk of Wound Infection after Colorectal Surgery?

Chemical prophylaxis using unfractionated heparin (UH) and low-molecular weight heparin is used in surgical patients to prevent venous thromboembolism. There is some evidence that prophylactic doses of heparin may increase the rate of surgical site infection (SSI) after elective orthopedic procedures. Little is known regarding the effect of heparin on SSI after colorectal procedures. We performed this study to study the effect of prophylactic unfractionated heparin on the rate of SSI after colorectal procedures. We did a retrospective analysis of 155 consecutive cases of patients of a single colorectal surgeon who underwent colorectal resection. Subcutaneous unfractionated heparin was given to 52 patients (29%). The rate of SSI in the group that received UH was 33 per cent versus 28 per cent in the group that did not receive UH ( P = 0.31). There was also no significant effect of prophylactic heparin on SSI noted among any patient subgroup. The use of prophylactic unfractionated heparin after colorectal procedures does not seem to increase the rate of surgical site infection.

Safety of glucocorticoids in cancer patients treated with oncolytic adenoviruses

Oncolytic adenoviruses are an emerging treatment option for advanced and refractory cancer. Such patients are often treated with corticosteroids to ameliorate tumor associated symptoms. Thus, it is important to evaluate whether safety is affected by immunosuppression possibly induced by corticosteroids. Concurrent low-dose cyclophosphamide, appealing for its immunomodulatory effects, could also impact safety. In a retrospective case-control study, we evaluated the effect of systemic corticosteroid use in cancer patients receiving oncolytic virotherapy. Four treatment groups were identified: (1) oncolytic adenovirus with oral glucocorticoids, (2) virus alone, (3) virus with glucocorticoids and cyclophosphamide and (4) virus with cyclophosphamide. Adverse events, neutralizing antibody titers, viral DNA in circulation and tumor responses were evaluated. The most common adverse effects were grade 1-2 fatigue, nausea, fever and abdominal pain. Common asymptomatic findings included self-limiting grade 1-3 hyponatremia and aspartate aminotransferase increase. Safety was good and no significant differences were observed between the groups. All patients had an increase in neutralizing antibody titers post-treatment, and no trends for differences between groups were observed. There were fewer post-treatment virus genomes circulating in patients receiving glucocorticoids when compared to their control groups. Overall, glucocorticoid use in cancer patients receiving oncolytic adenovirus, with or without low-dose cyclophosphamide, seems safe.

Asymptomatic deep vein thrombosis in advanced cancer patients: the value of venous sonography

PURPOSE

Although guidelines for venous thromboembolism prevention are available, the implementation of anticoagulant prophylaxis in patients with advanced cancer has yet to be more clearly defined. We aim to determine the incidence of lower extremity deep vein thrombosis (DVT) diagnosed by Doppler sonography (USD) in asymptomatic nonambulatory patients with advanced cancer.

METHOD

In a prospective study, 44 nonambulatory cancer patients with grade 3-4 World Health Organization performance status, asymptomatic for lower extremity DVT, underwent bilateral venous USD studies of the lower extremities. Different risk factors and laboratory data were registered and correlated with the incidence of DVT.

RESULT

Asymptomatic DVT was detected in 15 of 44 patients (34%, 95% CI, 0.21-0.49). Twenty-three percent of all patients had isolated deep calf vein thrombi and 11% of all patients had thrombi in the proximal veins. The only significant risk factor was the number of metastatic sites. DVT was found in 4 of 23 (17.4%) patients with one metastatic site as opposed to 11 of 21 (52.3%) with two or more sites (p < 0.01).

CONCLUSION

USD of the lower extremities detected asymptomatic DVT in 34% of advanced nonambulatory cancer patients and may serve as an additional decision-making tool in the consideration of anticoagulant therapy for this specific population.

Expression of protein C (PC), protein S (PS) and thrombomodulin (TM) in human colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is often complicated by thromboembolic episodes. It has been recognized that blood coagulation proteins play a role in cancer progression. An important inhibitory mechanism is provided by the protein C (PC) system consisting of PC, protein S (PS) and thrombomodulin (TM). Recently, novel biological activities have been ascribed to the PC system that do not relate to their hemostatic functions, eg. in angiogenesis, apoptosis and inflammation.

OBJECTIVES

The purpose of the study was to elucidate the solid phase interactions between CRC tissue and components of the PC system that may contribute to tumor progression.

MATERIAL AND METHODS

CRC tissues were obtained at surgical resection during treatment of 66 patients. Immunohistochemical studies were performed using polyclonal antibodies against PC, PS and TM. A semiquantitative analysis of the protein expression was also performed.

RESULTS

Weak expression of PC was observed in cancer cells of two-thirds of the specimens examined, while in 3/66 cases there was no staining for PC in cancer cells. One fourth of CRCs exhibited strong expression of PC. The presence of PS was demonstrated in 64/66 cases of CRC. However, its expression was irregular in terms of intensity of staining and percentage of cancer cells exhibiting protein expression. Weak expression of TM was demonstrated in two thirds of the cases examined, while a strong TM staining was revealed in one third of colon cancers.

CONCLUSION

Heterogeneous expression of the PC system components in CRC tissue may point to their biological activity modulating tumor growth.

A study of pulmonary embolism after abdominal surgery in patients undergoing prophylaxis

AIM: To determine risk factors for pulmonary embolism and estimate effects and benefits of prophylaxis.

METHODS: We included 78 patients who died subsequently to a pulmonary embolism after major abdominal surgery from 1985 to 2003. A first, retrospective analysis involved 41 patients who underwent elective surgery between 1985 and 1990 without receiving any prophylaxis. In the prospectively evaluated subgroup, 37 patients undergoing major surgery between 1991 and 2003 were enrolled: all of them had received a prophylaxis consisting in low-molecular weight heparin, given subcutaneously at a dose of 2850 IU AXa/0.3 mL (body weight < 50 kg) or 5700 IU AXa/0.6 mL (body weight ≥ 50 kg).

RESULTS: A higher incidence of thromboembolism (43.9% and 46.34% in the two groups, respectively) was found in older patients (> 60 years). The incidence of pulmonary embolism after major abdominal surgery in patients who had received the prophylaxis was significantly lower compared to the subjects with the same condition who had not received any prophylaxis (P < 0.001, OR = 2.825; 95% CI, 1.811-4.408). Furthermore, the incidence of pulmonary embolism after colorectal cancer surgery was significantly higher compared to incidence of pulmonary embolism after other abdominal surgical procedures. Finally, the incidence of pulmonary embolism after colorectal cancer surgery among the patients who had received the prophylaxis (11/4316, 0.26%) was significantly lower compared to subjects undergoing a surgical procedure for the same indication but without prophylaxis (10/1562, 0.64%) (P < 0.05, OR = 2.522; 95% CI, 1.069-5.949).

CONCLUSION: Prophylaxis with low molecular weight heparin is highly recommended during the preoperative period in patients with diagnosis of colorectal cancer due to high risk of pulmonary embolism after elective surgery.

Risk of deep vein thrombosis following laparoscopic rectosigmoid cancer resection in chinese patients

OBJECTIVE

The aim of this study was to evaluate the incidence of postoperative deep vein thrombosis (DVT) in Chinese patients who underwent laparoscopic resection of rectal or sigmoid cancer in the absence of thromboprophylaxis.

METHODS

Patients with adenocarcinoma of the sigmoid colon or rectum scheduled for laparoscopic resection were recruited. Neither chemoprophylaxis nor mechanical methods against DVT were employed. They were scheduled to have routine duplex ultrasound of both lower limbs perioperatively.

RESULTS

In a 12-month period, 50 patients were recruited. Postoperative DVT occurred in 19 (38%) patients. None needed anticoagulation. Complete resolution of the thrombus was noted in 10 (53%) patients 12 weeks after operation, and in six patients 36 weeks after operation. Female sex was identified as being associated with a higher incidence of DVT. Age, smoking, preoperative neoadjuvant chemoirradiation, preoperative metastasis, duration of operation, conversion and postoperative complications did not appear to be risk factors for DVT.

CONCLUSION

The incidence of asymptomatic calf vein DVT is relatively high after laparoscopic resection for rectosigmoid cancers in the Chinese population. However, complete resolution occurred without the use of anticoagulant therapy in the majority of cases. It is thus difficult to advocate the routine use of anticoagulant prophylaxis.

The impact of obesity on outcome after major colorectal surgery

PURPOSE

There is an epidemic of obesity in the Western world and its associated substantial morbidity and mortality. This review examines the data on the impact of obesity on perioperative morbidity and mortality specifically in the context of colorectal surgery.

METHODS

MEDLINE, PUBMED, and the Cochrane library were searched for relevant articles. A manual search for other pertinent papers also was performed.

RESULTS

There is good evidence that obesity is a risk factor for wound infection after colorectal surgery. Obesity may increase the risk of wound dehiscence, incisional site herniation, and stoma complications. Obesity is linked to anastomotic leak, and obese patient undergoing rectal resections may be at particular risk. There is little data on the impact of obesity on pulmonary and cardiovascular complications after colorectal surgery. Operation times are longer for rectal procedures in obese patients, but hospital stay is not prolonged. Obese patients undergoing laparoscopic colorectal surgery are at increased risk of conversion to an open procedure.

CONCLUSIONS

Obesity has a negative impact on outcome after colorectal surgery. To further clarify the impact of obesity on surgical outcome, it is recommended that future studies examine grades of obesity and include measures of abdominal obesity.

Epidemiology of acute deep vein thrombosis

Although the factors leading to venous thrombosis have been known for over a century, Virchow's initial model of thrombosis has been extensively refined. Activated coagulation is now recognized to be of primary importance in venous thrombogenesis; the concept of venous injury has been expanded to include molecular changes in the endothelium; and stasis has been redefined as a largely permissive factor. Furthermore, it is now clear that venous thrombi undergo a dynamic evolution beginning early after their formation. The natural history of acute deep venous thrombosis (DVT) is a balance between recurrent thrombotic events and processes that restore the venous lumen, both of which have important implications for the development of complications. Although pulmonary embolism (PE) is clearly the most life threatening complication of acute DVT, the long term socio-economic consequences of the post thrombotic syndrome (PTS) have perhaps been underemphasized in clinical trials. The development of post-thrombotic manifestations is related to both residual venous obstruction and valvular incompetence. Recognition of the factors contributing to a poor outcome, including recurrent thrombotic events, the rate of recanalization, the global extent of venous reflux, and the anatomic distribution of reflux and obstruction is important, as there may be therapeutic alternatives to alter the natural history of acute DVT. The treatment alternatives will continue to expand with the introduction of new therapeutic drugs, for both systemic and catheter-directed therapy, and mechanical thrombectomy devices. The primary care physician is challenged with the task of correctly evaluating deep vein thrombosis and providing his patient with access to the most clinically appropriate, and cost-effective, diagnostic and management options available. This article will review the epidemiology of DVT, its risk factors and major complications.

Venous thromboembolism prophylaxis for surgical patients in an Asian hospital

BACKGROUND

Venous thromboembolism (VTE) is increasingly recognized as a significant postoperative complication in Asian hospitals. Recommendations have been published for VTE prophylaxis. We conducted a prospective survey of the risk profile and measures used for VTE prophylaxis in elective surgical patients in our hospital.

METHODS

All patients who underwent elective general or orthopaedic surgery over a 4-week period were included. Information collected included demographic data, presence of risk factors, type and duration of surgery, perioperative use of VTE prophylaxis and any diagnosis of deep vein thrombosis or pulmonary embolism during the current admission as well as in any readmissions in the 6 weeks after discharge. The patients were classified based on their age, risk factors and type of surgery into low, moderate, high or highest risk and the prophylactic measures they received compared with published recommendations.

RESULTS

Two hundred and twenty-six patients underwent 227 elective surgeries over the 4-week period. There were 7 low, 16 moderate, 45 high and 55 highest risk patients. One hundred and three patients could not be classified. Postoperative prophylactic measures were omitted in 93.8%, 81.8% and 31.5% of patients in moderate, high and highest risk groups, respectively. One patient developed clinical deep vein thrombosis preoperatively and one postoperatively. There were no cases of pulmonary embolism.

CONCLUSIONS

VTE prophylaxis is underutilized in our survey. Further studies are required to identify the reasons for omission and to develop hospital specific protocols to increase appropriate use of prophylaxis.

Postoperative venous thromboembolism in Asia: a critical appraisal of its incidence

OBJECTIVES

Venous thromboembolism (VTE) has historically been perceived to be a rare disorder in Asia. However, new evidence has emerged recently that contradicts this perception. The question of routine VTE prophylaxis has been hotly debated in Asia due to disagreement on its incidence. We reviewed and analysed studies on postoperative VTE in Asian patients to determine if the condition was indeed rare and if the routine prophylactic measures as recommended by internationally accepted guidelines should be adopted in Asia.

METHODS

A review of published reports, from 1966 to December 2002, on deep vein thrombosis (DVT) and pulmonary embolism (PE) in the Asian population was made. A literature search of studies published in English was conducted via a detailed MEDLINE search. Studies had to attain a minimum inclusion and quality criteria to be accepted for the review, including the diagnostic modality used for the diagnosis of VTE. The appraisal was carried out independently and accepted by at least two of the three authors. The study population was classified into orthopaedic and general surgical/colorectal groups.

RESULTS

Twelve orthopaedic publications reviewed revealed an incidence of postoperative DVT of 10% to 63%. Six general and colorectal surgical publications reported an incidence of DVT ranging from 3% to 28%. The incidence was slightly lower than the reported incidence of 40% to 80% following orthopaedic surgery and 28% to 44% following general surgical operations in studies reporting on Caucasian populations.

CONCLUSION

While there is a wide variation in the incidence of DVT and VTE as reported in the Asian population, these diseases are by no means rare. The wide variation could be due to the study designs, heterogeneity of the procedures performed and the application of different diagnostic criteria. Results based on prospective studies with objective diagnostic criteria confirm the incidence of VTE as common. Routine chemoprophylaxis must be seriously considered in high-risk patients.