Accuracy of Blood Loss Measurement during Cesarean Delivery

[Visual estimation of blood losses : Known high error rate-How can it be improved?]

Every day blood losses are visually estimated by medical personnel (physicians, midwives, paramedics) because an exact quantitative measurement is impossible or impractical. Anesthesiologists are confronted with blood loss in the operating room, in the delivery room, in the emergency room and at the scene of an emergency; however, the literature shows that in all the named areas enormous errors occur in the visual estimation. Errors of 50% and more are not uncommon, which means that, e.g., an estimated blood loss of 2000ml could actually be 3000ml or only 1000ml. General, in all the abovenamed areas blood losses are more likely to be underestimated than overestimated. The ability to make an estimation is not improved by professional experience. The amount of blood loss indicates and "justifies" invasive measures and the administration of blood and cost-intensive blood products. This overview is dedicated to the problems in the estimation of blood loss, demonstrates the sequelae of an incorrectly estimated blood loss, provides tips on how the ability to make an estimation can be improved and describes the considerable potential of further education as well as which digital support options are now available.

Calculation methods for intraoperative blood loss: a literature review

Intraoperative bleeding is a common issue in various surgical procedures, and the extent of bleeding significantly impacts the safety, efficacy, and prognosis of surgery. Therefore, accurate assessment of intraoperative blood loss and timely intervention are essential for the smooth progression of surgery and favorable clinical outcomes. Currently, clinical methods for estimating blood loss are generally classified into two main categories: visual and calculation methods. Calculation methods are further delineated into weighing techniques and concentration-based approaches. Although the visual method is criticized for its subjectivity and inaccuracy, it remains the most widely used approach in clinical practice for assessing intraoperative blood loss. This article reviews different methods for assessing blood loss during surgery and compares their respective advantages and disadvantages, aiming to provide surgeons with a more reliable foundation for intraoperative blood loss evaluation.

Maintenance infusion rate of oxytocin after initial 1-IU bolus for elective Cesarean delivery: a dose-finding study

PURPOSE

The purpose of our study was to determine the minimum effective dose of oxytocin maintenance infusion required to maintain adequate uterine tone in 90% of patients (ED90) after administration of the initial bolus at elective Cesarean delivery (CD) under spinal anesthesia.

METHODS

We conducted a prospective, double-blind dose-finding study with biased coin up-down design. Immediately after delivery, a 1-IU oxytocin bolus was administered, followed by a maintenance infusion. The obstetrician assessed the uterine tone by palpation as satisfactory or unsatisfactory. In case of unsatisfactory response, the dose for the next patient was increased by 2 IU·hr-1. For satisfactory response, the dose for the next patient was either decreased by 2 IU·hr-1 with a probability of 1/9, or remained unchanged. The primary outcome was a satisfactory uterine tone from five minutes after delivery until discharge from postanesthesia care unit. The secondary outcomes were blood loss, need for additional uterotonics, and side effects.

RESULTS

We analyzed data for 40 patients. The ED90 of oxytocin maintenance infusion was 4.5 IU·hr-1 (95% confidence interval, 3.3 to 5.5) based on the isotonic regression estimator. The median [interquartile range] blood loss was 861 [553-1,181] mL; 18% received additional uterotonics, and 38% developed hypotension post delivery.

CONCLUSION

Based on the results of this dose-finding study, we recommend a maintenance infusion rate of 4.5 IU·hr-1 following an oxytocin bolus of 1 IU for adequate uterine tone in pregnant patients undergoing elective CDs. This infusion rate is four-fold lower than that required without an initial bolus.

STUDY REGISTRATION

ClinicalTrials.gov ( NCT04946006 ); first submitted 25 June 2021.

Quantification of blood loss for the diagnosis of postpartum hemorrhage: a systematic review and meta-analysis

OBJECTIVE

to compare the effectiveness of different diagnostic methods to estimate postpartum blood volume loss.

METHODS

a systematic review of effectiveness according to PRISMA and JBI Protocol. Searches in PubMed/MEDLINE, LILACS, Scopus, Embase, Web of Science and CINAHL, with descriptor "Postpartum Hemorrhage" associated with keyword "Quantification of Blood Loss". Tabulated extracted data, presented in metasynthesis and meta-analysis was applied to quantitative data. To assess risk of bias, JBI Appraisal Tools were applied.

RESULTS

fourteen studies were included, published between 2006 and 2021. Quantification of loss by any method was superior to visual estimation and is highly recommended, however the studies' high heterogeneity did not allow estimating this association.

CONCLUSION

the studies' high heterogeneity, with a probable margin of error given the uncontrolled factors, indicates the need for further studies, however quantification proved to be effective in relation to visual estimate. PROSPERO registration CRD 42021234486.

Radiomics-based prediction of FIGO grade for placenta accreta spectrum

BACKGROUND

Placenta accreta spectrum (PAS) is a rare, life-threatening complication of pregnancy. Predicting PAS severity is critical to individualise care planning for the birth. We aim to explore whether radiomic analysis of T2-weighted magnetic resonance imaging (MRI) can predict severe cases by distinguishing between histopathological subtypes antenatally.

METHODS

This was a bi-centre retrospective analysis of a prospective cohort study conducted between 2018 and 2022. Women who underwent MRI during pregnancy and had histological confirmation of PAS were included. Radiomic features were extracted from T2-weighted images. Univariate regression and multivariate analyses were performed to build predictive models to differentiate between non-invasive (International Federation of Gynecology and Obstetrics [FIGO] grade 1 or 2) and invasive (FIGO grade 3) PAS using R software. Prediction performance was assessed based on several metrics including sensitivity, specificity, accuracy and area under the curve (AUC) at receiver operating characteristic analysis.

RESULTS

Forty-one women met the inclusion criteria. At univariate analysis, 0.64 sensitivity (95% confidence interval [CI] 0.0-1.00), specificity 0.93 (0.38-1.0), 0.58 accuracy (0.37-0.78) and 0.77 AUC (0.56-.097) was achieved for predicting severe FIGO grade 3 PAS. Using a multivariate approach, a support vector machine model yielded 0.30 sensitivity (95% CI 0.18-1.0]), 0.74 specificity (0.38-1.00), 0.58 accuracy (0.40-0.82), and 0.53 AUC (0.40-0.85).

CONCLUSION

Our results demonstrate a predictive potential of this machine learning pipeline for classifying severe PAS cases.

RELEVANCE STATEMENT

This study demonstrates the potential use of radiomics from MR images to identify severe cases of placenta accreta spectrum antenatally.

KEY POINTS

• Identifying severe cases of placenta accreta spectrum from imaging is challenging. • We present a methodological approach for radiomics-based prediction of placenta accreta. • We report certain radiomic features are able to predict severe PAS subtypes. • Identifying severe PAS subtypes ensures safe and individualised care planning for birth.

Evaluation During Postpartum Hemorrhage

Postpartum hemorrhage is an obstetric emergency that is the leading and the most preventable cause of maternal death that occurs on the day of birth. The treatment of postpartum hemorrhage in a timely fashion is crucial to prevent morbidity and mortality. The accurate assessment of blood loss during delivery and the postpartum period remains a major challenge. Hence, it is imperative to have a standardized evaluation strategy for accurate assessment of blood loss, adequate classification of hemorrhage, and timely initiated interventions. The multidisciplinary evaluation strategy should be in place regardless of the delivery route.

Effect of implementation of a colorimetric quantitative blood loss system for postpartum hemorrhage

OBJECTIVE

To evaluate if the implementation of a colorimetric quantitative blood loss (QBL) system during cesarean delivery improves clinical outcomes.

METHODS

We conducted a retrospective cohort analysis after cesarean section before and after implementation of the Triton based colorimetric QBL system. Prevalence of postpartum hemorrhage, amount of blood products transfused, length of hospitalization, and rates of intensive care unit (ICU) admission were compared.

RESULTS

A total of 2221 patients were included. There were 1192 patients in the pre-intervention group and 1029 patients in the post-intervention group. There was no significant difference between groups in the prevalence of postpartum hemorrhage (8.6% vs 9.3%, P = 0.57), amount of packed red blood cells (pRBCs) transfused (45 vs 30, P = 0.41) or average length of hospital stay in days (3.0 vs 3.0, P = 0.37). There was a statistically significant decrease in ICU admissions between the pre- and post-intervention groups (2.2% vs 1.0%, P = 0.02).

CONCLUSION

There was no effect of implementation of the colorimetric QBL application system on diagnosis of postpartum hemorrhage, amount of blood products transfused, or length of hospital stay. Although a significant decrease in ICU admissions was observed, we could not determine if these transfers were hemorrhage related.

Carbetocin vs. oxytocin at elective caesarean delivery: a double-blind, randomised, controlled, non-inferiority trial of low- and high-dose regimens

Carbetocin or oxytocin are given routinely as first-line uterotonic drugs following delivery of the neonate during caesarean delivery to prevent postpartum haemorrhage. Low doses may be as effective as high doses with a potential reduction in adverse effects. In this double-blind, randomised, controlled, non-inferiority trial, we assigned low-risk patients undergoing elective caesarean delivery under spinal anaesthesia to one of four groups: carbetocin 20 μg; carbetocin 100 μg; oxytocin 0.5 IU bolus + infusion; and oxytocin 5 IU bolus + infusion. The study drug was given intravenously after delivery of the neonate. Uterine tone was assessed by the obstetrician 2, 5 and 10 minutes after study drug administration according to an 11-point verbal numerical rating scale (0 = atonic, 10 = excellent tone). The primary outcome measure was uterine tone 2 min after study drug administration. The pre-specified non-inferiority margin was 1.2 points on the 11-point scale. Secondary outcomes included uterine tone after 5 and 10 minutes, use of additional uterotonics, blood loss and adverse effects. Data were available for 277 patients. Carbetocin 20 μg resulting in uterine tone of (median (IQR [range])) 8 (7-8 [1-10]) was non-inferior to carbetocin 100 μg with tone 8 (7-9 [3-10]), median (95%CI) difference 0 (-0.44-0.44). Similarly, oxytocin 0.5 IU with tone 7 (6-8 [3-10]) was non-inferior to oxytocin 5 IU with tone 8 (6-8 [2-10]), median (95%CI) difference 1 (0.11-1.89). Carbetocin 20 μg was also non-inferior to oxytocin 5 IU, and oxytocin 0.5 IU was non-inferior to carbetocin 100 μg. Uterine tone after 5 and 10 minutes, use of additional uterotonics, blood loss and adverse effects were similar in all groups.

Latest advances in postpartum hemorrhage management

Hemorrhage is the leading cause of maternal mortality worldwide. A maternal health priority is improving how healthcare providers prevent and manage postpartum hemorrhage (PPH). Because anesthesiologists can help facilitate how hospitals develop approaches for PPH prevention and anticipatory planning, we review the potential utility of PPH risk-assessment tools, bundles, and protocols. Anesthesiologists rely on clinical and diagnostic information for initiating and evaluating medical management. Therefore, we review modalities for measuring blood loss after delivery, which includes visual, volumetric, gravimetric, and colorimetric approaches. Point-of-care technologies for assessing changes in central hemodynamics (ultrasonography) and coagulation profiles (rotational thromboelastometry and thromboelastography) are also discussed. Anesthesiologists play a critical role in the medical and transfusion management of PPH. Therefore, we review blood ordering and massive transfusion protocols, fixed-ratio vs. goal-directed transfusion approaches, coagulation changes during PPH, and the potential clinical utility of the pharmacological adjuncts, tranexamic acid, and fibrinogen concentrate.

Preventing postpartum hemorrhage after cesarean delivery: a network meta-analysis of available pharmacologic agents

BACKGROUND

Postpartum hemorrhage causes a quarter of global maternal deaths. The World Health Organization recommends oxytocin as the first line agent to prevent hemorrhage during cesarean delivery. However, some randomized controlled trials suggest that other uterotonics are superior.

OBJECTIVE

We conducted a network meta-analysis comparing the ability of pharmacologic agents to reduce blood loss and minimize the need for additional uterotonics during cesarean delivery.

DATA SOURCES

We searched the Cochrane Central Register of Controlled Trials, Embase, and MEDLINE databases from inception to May 2020.

STUDY ELIGIBILITY CRITERIA

We included randomized controlled trials that compared oxytocin, carbetocin, misoprostol, ergometrine, carboprost, or combinations of these in the prevention of postpartum hemorrhage during cesarean delivery.

METHODS

We performed a systematic review followed by an NMA in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Quality of the evidence was assessed with the Confidence in Network Meta-Analysis approach and Grading of Recommendations, Assessment, Development and Evaluations tool within the summary of findings table. Our primary outcomes were the estimated blood loss and need for additional uterotonics. Secondary outcomes included nausea and postpartum hemorrhage of >1000 mL. We performed sensitivity analyses to explore the influence of surgical context and oxytocin administration strategy.

RESULTS

A total of 46 studies with 7368 participants were included. Of those, 21 trials (6 agents and 3665 participants) formed the "estimated blood loss" network and, considering the treatment effects, certainty in the evidence, and surface under the cumulative ranking curve scores, carbetocin was assessed to probably be superior to oxytocin, but only in reducing the estimated blood loss by a clinically insignificant volume (54.83 mL; 95% confidence interval, 26.48-143.78). Misoprostol, ergometrine, and the combination of oxytocin and ergometrine were assessed to probably be inferior, whereas the combination of oxytocin and misoprostol was assessed to definitely be inferior to oxytocin. A total of 37 trials (8 agents and 6193 participants) formed the "additional uterotonic" network and, again, carbetocin was assessed to probably be superior to oxytocin, requiring additional uterotonics 185 (95% confidence interval, 130-218) fewer times per 1000 cases. Oxytocin plus misoprostol, oxytocin plus ergometrine, and misoprostol were assessed to probably be inferior, whereas carboprost, ergometrine, and the placebo were definitely inferior to oxytocin. For both primary outcomes, oxytocin administration strategies had a higher probability of being the best uterotonic, if initiated as a bolus.

CONCLUSION

Carbetocin is probably the most effective agent in reducing blood loss and the need for additional uterotonics. Oxytocin appears to be more effective when initiated as a bolus.

Limitations of Gravimetric Quantitative Blood Loss during Cesarean Delivery

Objective  This study examined the accuracy, sources of error, and limitations of gravimetric quantification of blood loss (QBL) during cesarean delivery. Study Design  Blood loss determined by assays of the hemoglobin content on surgical sponges and in suction canisters was compared with QBL in 50 parturients. Results  QBL was moderately correlated to the actual blood loss ( r  = 0.564; p  < 0.001). Compared with the reference assay, QBL overestimated blood loss for 44 patients (88%). QBL deviated from the assayed blood loss by more than 250 mL in 34 patients (68%) and by more than 500 mL in 16 cases (32%). Assayed blood loss was more than 1,000 mL in four patients. For three of these patients, QBL was more than 1,000 mL (sensitivity = 75%). QBL was more than 1,000 mL in 12 patients. While three of these had an assayed blood loss of more than 1,000 mL, 9 of the 46 patients with blood losses of less than 1,000 mL by the assay (20%) were incorrectly identified as having postpartum hemorrhage by QBL (false positives). The specificity of quantitative QBL for detection of blood loss more than or equal to 1,000 mL was 80.4%. Conclusion  QBL was only moderately correlated with the reference assay. While overestimation was more common than underestimation, both occurred. Moreover, QBL was particularly inaccurate when substantial bleeding occurred. Key Points QBL is inaccurate in cesarean delivery.QBL deviated from the assay result by more than 500 mL in 32% of cases.QBL sensitivity and specificity for hemorrhage is 75.0% (95% confidence interval [CI]: 0.19-0.93) and 80.4% (95% CI: 0.69-0.92), respectively.

Placenta accreta risk-antepartum score in predicting clinical outcomes of placenta accreta spectrum: A multicenter validation study

OBJECTIVE

To validate the use of placenta accreta risk-antepartum (PAR-A) score as a predictive tool of clinical outcomes of placenta accreta spectrum (PAS).

METHODS

This is a prospective study, conducted in six PAS specialized centers in six different countries. The study was conducted between October 1, 2020 and March 31, 2021. Women who were provisionally diagnosed with PAS during pregnancy were considered eligible. A machine-learning-based PAR-A score was calculated. Diagnostic performance of the PAR-A score was evaluated using a receiver operating characteristic curve, for perioperative massive blood loss and admission to intensive care unit (ClinicalTrials.gov identifier NCT04525001).

RESULTS

Of 97 eligible women, 86 were included. PAS-associated massive blood loss occurred in 10 patients (11.63%). Median PAR-A scores of massive blood loss in the current cohort were 8.9 (interquartile range 6.9-14.1). In predicting massive blood loss, the area under the curve of PAR-A scores was 0.85 (95% confidence interval [CI] 0.74-0.95), which was not significantly different from the original cohort (P = 0.2). PAR-A score prediction of intensive care unit admission was slightly higher compared with the original cohort (0.88, 95% CI 0.81-0.95; P = 0.06).

CONCLUSION

PAR-A score is a novel scoring system of PAS outcomes, which showed external validity based on current data.

Automated Quantification of Blood Loss versus Visual Estimation in 274 Vaginal Deliveries

OBJECTIVE

The aim of the study is to compare quantified blood loss measurement (QBL) using an automated system (Triton QBL, Menlo Park, CA) with visual blood loss estimation (EBL) during vaginal delivery.

STUDY DESIGN

During 274 vaginal deliveries, both QBL and EBL were determined. The automated system batch weighs blood containing sponges, towels, pads, and other supplies and automatically subtracts their dry weights and also the measured amount of amniotic fluid. Each method was performed independently, and clinicians were blinded to the device's results.

RESULTS

Median QBL (339 mL [217-515]) was significantly greater than median EBL (300 mL [200-350]; p < 0.0001). The Pearson's correlation between EBL and QBL was poor (r = 0.520) and the Bland-Altman's limits of agreement were wide (>900 mL). QBL measured blood loss >500 mL occurred in 73 (26.6%) patients compared with 14 (5.1%) patients using visual estimation (p < 0.0001). QBL ≥  1,000 mL was recorded in 11 patients (4.0%), whereas only one patient had an EBL blood loss of 1,000 mL and none had EBL >1,000 mL (p = 0.002).

CONCLUSION

Automated QBL recognizes more patients with excessive blood loss than visual estimation. To realize the value of QBL, clinicians must accept the inadequacy of visual estimation and implement protocols based on QBL values. Further studies of clinical outcomes related to QBL are needed.

KEY POINTS

· QBL detects hemorrhage more frequently than visual estimation.. · Median QBL is significantly greater than median EBL.. · There is poor agreement between QBL and EBL..

Evaluation of blood transfusion rates by blood loss estimation techniques

BACKGROUND

Postpartum hemorrhage is a major cause of maternal morbidity and mortality. Though the American College of Obstetricians and Gynecologists and quality improvement initiatives recommend the use of a quantitative measurement of blood loss, it is not known if the quantitative measurement compared to visual estimation of blood loss improves maternal outcomes.

OBJECTIVE

To compare rates of red blood cell transfusion between a quantitative measurement and visual estimation of blood loss.

STUDY DESIGN

This was a retrospective cohort study of all women who underwent cesarean delivery at a single academic institution from January 2012 to June 2018. Women were excluded if they received a preoperative transfusion or had missing data. Our institution implemented a quantitative measurement of blood loss in September 2015. Our primary outcome was red blood cell transfusion (intraoperative or postoperative). Women who had the quantitative measurement of blood loss (October 2015 to June 2018) were compared with those who had a visual estimation of blood loss (January 2012 to August 2015). Coarsened Exact Matching with a k-to-k solution was performed using predefined variables.

RESULTS

In total, 4068 had a visual estimation of blood loss and 3117 had the quantitative measurement of blood loss; 1101 women with the quantitative measurement of blood loss were matched to 1101 women with a visual estimation of blood loss. In the unmatched cohort, women who had the quantitative measurement of blood loss compared to those who had a visual estimation of blood loss were more likely to have an increased amount of blood loss (734 ml vs. 700 ml, p < .001) and red blood cell transfusion (7.2% [223/3117] vs. 5.4% [221/4068]; crude odds ratio 1.34; 95% confidence interval 1.11-1.63). This increase in the amount of blood loss (717 ml vs. 700 ml, p < .05) and the rate of red blood cell transfusion (4.5% [49/1101] vs. 2.7% [30/1101]; crude odds ratio 1.66; 95% confidence interval 1.05-2.64) remained statically significant after matching.

CONCLUSION

Women who had the quantitative measurement compared with those who had a visual estimation of blood loss were more likely to have an increased amount of blood loss and red blood cell transfusion.

Delivery method of the placenta in cesarean deliveries and the effect of uterine incision repair area on morbidity: A randomized controlled study

Objective

We evaluated the effects of spontaneous or manual delivery of the placenta and repair of uterine incision inside or outside the abdomen on intraoperative blood loss, postoperative infection morbidity, and postoperative hospitalization time.

Materials and Methods

We conducted a prospective randomized controlled study with 150 patients among 160 patients who were indicated to undergo emergency cesarean procedures in our tertiary hospital. We divided the patient population into four groups. These four groups were formed by comparing the way the placenta was delivered manually and by spontaneous traction with the repair of the uterus inside and outside the abdomen. Blood loss was determined using quantitative and gravimetric methods. A numeric rating scale was used, which is a one-dimensional method used for uterine sensitivity distribution and pain measurement.

Results

The amount of bleeding was 339 mL in group 1, 237 mL in group 2, 470 mL in group 3, and 490 mL in group 4, which were significantly different (p<0.001). The mean surgical time was 30.8±5.5 minutes in group 1, 30.7±4.4 minutes in group 2, 38.5±6.9 minutes in group 3, and 43.9 minutes in group 4 (p<0.001). When the distribution of uterine tenderness among the groups was examined in the fundus examinations performed on the postpartum 1st day of the patients, we found a significant difference (p<0.001). When all groups were compared, there was a significant difference between group 1 and group 4 in terms of hospital stay (p<0.004). Among the contributing factors were endometritis, maternal body weight (p<0.053), advanced gestational week (p<0.004), prolonged surgical time (p<0.009), and the presence of meconium.

Conclusion

Manual removal of the placenta resulted in higher blood loss, increased uterine tenderness, and longer hospitalization compared with the spontaneous separation method. The uterine incision repair site did not affect morbidity.

Comparison of common perioperative blood loss estimation techniques: a systematic review and meta-analysis

Estimating intraoperative blood loss is one of the daily challenges for clinicians. Despite the knowledge of the inaccuracy of visual estimation by anaesthetists and surgeons, this is still the mainstay to estimate surgical blood loss. This review aims at highlighting the strengths and weaknesses of currently used measurement methods. A systematic review of studies on estimation of blood loss was carried out. Studies were included investigating the accuracy of techniques for quantifying blood loss in vivo and in vitro. We excluded nonhuman trials and studies using only monitoring parameters to estimate blood loss. A meta-analysis was performed to evaluate systematic measurement errors of the different methods. Only studies that were compared with a validated reference e.g. Haemoglobin extraction assay were included. 90 studies met the inclusion criteria for systematic review and were analyzed. Six studies were included in the meta-analysis, as only these were conducted with a validated reference. The mixed effect meta-analysis showed the highest correlation to the reference for colorimetric methods (0.93 95% CI 0.91-0.96), followed by gravimetric (0.77 95% CI 0.61-0.93) and finally visual methods (0.61 95% CI 0.40-0.82). The bias for estimated blood loss (ml) was lowest for colorimetric methods (57.59 95% CI 23.88-91.3) compared to the reference, followed by gravimetric (326.36 95% CI 201.65-450.86) and visual methods (456.51 95% CI 395.19-517.83). Of the many studies included, only a few were compared with a validated reference. The majority of the studies chose known imprecise procedures as the method of comparison. Colorimetric methods offer the highest degree of accuracy in blood loss estimation. Systems that use colorimetric techniques have a significant advantage in the real-time assessment of blood loss.

Can measuring blood loss at delivery reduce hemorrhage-related morbidity?

Quantitation of blood loss after vaginal and cesarean delivery has been advocated for the timely detection of postpartum hemorrhage and activation of protocols for resuscitation. Morbidity and mortality from postpartum hemorrhage is considered to be largely preventable and is attributed to delayed recognition with under-resuscitation or inappropriate resuscitation. Optimizing detection of postpartum hemorrhage through refining how blood loss is measured is therefore clinically relevant. In this review on quantitative blood loss for postpartum hemorrhage, recent advances in the methods used to quantitate blood loss will be reviewed, with a comparison of utility and precision for blood loss measurement after vaginal and cesarean delivery. Considerations for the implementation of a quantitative blood loss system on the labor and delivery unit, including its benefits and challenges, will be discussed. The existing evidence for impact of blood loss quantitation in obstetrics on hemorrhage-related morbidity will be delineated, along with knowledge gaps and future research priorities.

The visually estimated blood volume in scaled canisters based on a simulation study

BACKGROUND

The most common technique used worldwide to quantify blood loss during an operation is the visual assessment by the attending intervention team. In every operating room you will find scaled suction canisters that collect fluids from the surgical field. This scaling is commonly used by clinicians for visual assessment of intraoperative blood loss. While many studies have been conducted to quantify and improve the inaccuracy of the visual estimation method, research has focused on the estimation of blood volume in surgical drapes. The question whether and how scaling of canisters correlates with actual blood loss and how accurately clinicians estimate blood loss in scaled canisters has not been the focus of research to date.

METHODS

A simulation study with four "bleeding" scenarios was conducted using expired whole blood donations. After diluting the blood donations with full electrolyte solution, the sample blood loss volume (SBL) was transferred into suction canisters. The study participants then had to estimate the blood loss in all four scenarios. The difference to the reference blood loss (RBL) per scenario was analyzed.

RESULTS

Fifty-three anesthetists participated in the study. The median estimated blood loss was 500 ml (IQR 300/1150) compared to the RBL median of 281.5 ml (IQR 210.0/1022.0). Overestimations up to 1233 ml were detected. Underestimations were also observed in the range of 138 ml. The visual estimate for canisters correlated moderately with RBL (Spearman's rho: 0.818; p < 0.001). Results from univariate nonparametric confirmation statistics regarding visual estimation of canisters show that the deviation of the visual estimate of blood loss is significant (z = - 10.95, p < 0.001, n = 220). Participants' experience level had no significant influence on VEBL (p = 0.402).

CONCLUSION

The discrepancies between the visual estimate of canisters and the actual blood loss are enormous despite the given scales. Therefore, we do not recommend estimating the blood loss visually in scaled suction canisters. Colorimetric blood loss estimation could be a more accurate option.

Do we visually estimate intra-operative blood loss better with white or green sponges and is the deviation from the real blood loss clinically acceptable? Results from a simulated scenario study

BACKGROUND

The intraoperative blood loss is estimated daily in the operating room and is mainly done by visual techniques. Due to local standards, the surgical sponge colours can vary (e.g. white in US, green in Germany). The influence of sponge colour on accuracy of estimation has not been in the focus of research yet.

MATERIAL AND METHODS

A blood loss simulation study containing four "bleeding" scenarios each per sponge colour were created by using expired whole blood donation samples. The blood donations were applied to white and green surgical sponges after dilution with full electrolyte solution. Study participants had to estimate the absorbed blood loss in sponges in all scenarios. The difference to the reference blood loss was analysed. Multivariate linear regression analysis was performed to investigate other influence factors such as staff experience and sponge colour.

RESULTS

A total of 53 anaesthesists participated in the study. Visual estimation correlated moderately with reference blood loss in white (Spearman's rho: 0.521; p = 3.748*10-16) and green sponges (Spearman's rho: 0.452; p = 4.683*10-12). The median visually estimated blood loss was higher in white sponges (250ml IRQ 150-412.5ml) than in green sponges (150ml IQR 100-300ml), compared to reference blood loss (103ml IQR 86-162.8). For both colour types of sponges, major under- and overestimation was observed. The multivariate statistics demonstrates that fabric colours have a significant influence on estimation (p = 3.04*10-10), as well as clinician's qualification level (p = 2.20*10-10, p = 1.54*10-08) and amount of RBL to be estimated (p < 2*10-16).

CONCLUSION

The deviation of correct blood loss estimation was smaller with white surgical sponges compared to green sponges. In general, deviations were so severe for both types of sponges, that it appears to be advisable to refrain from visually estimating blood loss whenever possible and instead to use other techniques such as e.g. colorimetric estimation.

Introduction of standardized, cumulative quantitative measurement of blood loss into routine maternity care

Introduction: Postpartum hemorrhage (PPH) is the leading cause of maternal morbidity in the UK. Visual estimation of blood loss is unreliable yet remains common practice. As part of a national quality improvement project to improve care during PPH, standardized, quantitative measurement of blood loss (QBL) for all deliveries was introduced into a tertiary obstetric unit in Cardiff, Wales.Methods: Retrospective analysis of 875 consecutive maternities between December 2017 and February 2018 was undertaken. Of these, 372 mothers had both pre- and post-partum hemoglobin (Hb) were recorded. Regression analyses were performed to investigate the relationship between change in Hb adjusted for red cell transfusion and QBL.Results: The correlation coefficient between QBL and adjusted change in Hb for all deliveries (n = 372) was 0.57. This corresponded to an estimated fall of adjusted change in Hb of 15.3 g/L (95% CI: 13.1, 17.6) per 1000 mL blood loss.Discussion: QBL has been shown to be reliable across all maternity settings, with reproducible results in theater and delivery rooms (on the obstetric unit and alongside midwifery-led unit). QBL is moderately correlated with adjusted change in Hb for all volumes of bleeding and gives clinicians more accurate knowledge of blood loss than visual estimation. This low-cost, low-fidelity intervention can influence the timely escalation of clinical care and therefore patient outcome.

Hemodynamic effects of carbetocin administered as an intravenous bolus or infusion during cesarean delivery

Background

Postpartum hemorrhage is the leading cause of maternal mortality. Oxytocin being the most popular uterotonic agent, has been routinely administered after both vaginal delivery and cesarean section. Carbetocin is a newer uterotonic agent and provides the benefit of a longer duration of action without additional administration post-delivery.

Methods

We recruited 34 women undergoing elective cesarean section under spinal anesthesia. All patient was received spinal anesthesia using 0.5% hyperbaric Marcaine 8–10 mg in conjugation with fentanyl 20 μg in the left lateral decubitus position. Hartmann’s solution 10–15 ml/kg was administered before carbetocin. The operation started as soon as sensory block at level T4–T6 was confirmed. A non-invasive hemodynamic monitoring cuff (Finometer^®) was attached to the patient’s finger soon after the induction of spinal anesthesia. Using the Finometer, we recorded the heart rate and mean arterial pressure at every 15 s, starting from 15 s before the administration of carbetocin to 5 min after. After the removal of the placenta, the bolus group was administered intravenous bolus injection of carbetocin 100 μg and the infusion group was administered carbetocin 100 μg diluted in 50 ml normal saline, over 5 min using an infusion pump.

Results

The demographic data showed no significant difference between the two groups. Furthermore, there were no significant hemodynamic differences between the two groups.

Conclusions

The method of administration of carbetocin does not influence its hemodynamic effects.

Importance of Estimated Blood Loss in Resource Utilization and Complications of Hysterectomy for Benign Indications

OBJECTIVE

To identify the variation in estimated blood loss at the time of hysterectomy for benign indications and to analyze how blood loss is associated with measures of resource utilization and complications.

METHODS

We conducted a retrospective cohort study and analyzed hysterectomy for benign indications at hospitals in the Michigan Surgical Quality Collaborative between January 1, 2013, and May 30, 2015. A sensitivity analysis was performed to identify how estimated blood loss was associated with measures of utilization (transfusion, readmission, reoperation, and length of stay) and postoperative complications. A hierarchical logistic regression model was used to identify patient level factors independently associated with estimated blood loss greater than 400 mL and to calculate a risk- and reliability-adjusted rate for each hospital.

RESULTS

There were 18,033 hysterectomies for benign indications from 61 hospitals included for analysis. The median estimated blood loss was 100 mL, and the 90th percentile estimated blood loss was 400 mL. A sensitivity analysis demonstrated increased risks of transfusion, readmission, reoperation, length of stay, and major postoperative complications with estimated blood loss greater than 400 mL. The proportion of hysterectomies at hospitals in the collaborative with estimated blood loss greater than 400 mL ranged from 3.5% to 16.9% after risk and reliability adjustments. The risk factors with the highest adjusted odds for estimated blood loss greater than 400 mL included abdominal surgery compared with laparoscopic hysterectomy (adjusted odds ratio [aOR] 2.8, CI 2.3-3.5), surgical time longer than 3 hours (aOR 3.9, CI 3.3-4.5), and specimen weight greater than 250 g compared with less than 100 g (aOR 4.8, CI 3.9-5.8). Adhesive disease, low surgeon volume, being younger than 40 years of age, having a body mass index greater than 35, and the need for a preoperative transfusion were also statistically significantly associated with estimated blood loss greater than 400 mL.

CONCLUSION

There is fivefold variation in the hospital rate of hysterectomies with an estimated blood loss greater than 400 mL (90th percentile)-a threshold associated with significantly higher rates of health care utilization and complications. Avoidance of abdominal hysterectomy when possible may reduce intraoperative blood loss and associated sequelae.

Implementing Delayed Umbilical Cord Clamping in Cesarean Birth Using a Novel Method: A Pilot Study of Feasibility and Safety

INTRODUCTION

Although delayed cord clamping (DCC) is regarded as the standard of care for all vigorous newborns, those born via cesarean birth are less likely to be afforded this option, especially for longer than 30 to 60 seconds. This pilot study was undertaken to determine whether removal of the placenta before cord clamping to allow for DCC of at least 3 minutes during term, uncomplicated cesarean birth is feasible and without apparent safety issues in order to support a large prospective study on the benefits of this method.

METHODS

Women having a term, uncomplicated cesarean birth who consented to the study were enrolled. Safety was assessed by comparing estimated maternal blood loss, newborn Apgar scores, temperatures, transcutaneous bilirubin levels, need for phototherapy, and neonatal intensive care unit admissions with a matched historical control group of women whose newborns had immediate cord clamping. Feasibility was measured by evaluating staff and maternal comfort with the intervention and by the ability to complete the protocol steps.

RESULTS

Seventeen women consented to participate. The protocol was successfully completed in 94% of births. There were no differences in maternal and neonatal safety outcome measures between groups. There was high comfort level with the protocol among staff, and there was universal maternal satisfaction.

DISCUSSION

This method of DCC in cesarean birth appears feasible and safe in this small pilot study and was associated with high maternal satisfaction and clinician comfort. Major organizations such as the American College of Nurse-Midwives and the World Health Organization have called for DCC of up to 3 to 5 minutes in all births, and this simple method has the potential to reach that goal in cesarean birth with minimal apparent risk. A large randomized controlled trial is warranted to determine the neonatal and maternal benefits and safety of this technique compared with a 30-to-60-second delay.

Validation of a new method to assess estimated blood loss in the obstetric population undergoing cesarean delivery

BACKGROUND

Postpartum hemorrhage is the leading cause of maternal mortality in developing countries and the primary cause of one-quarter of all maternal deaths globally. Inaccuracy in estimating blood loss obscures the diagnosis of postpartum hemorrhage and its management.

OBJECTIVE

Our objective was to compare assessment of blood loss using the quantitative Triton system (Gauss Surgical, Inc, Los Altos, CA) with other measures of blood loss in women undergoing cesarean delivery.

STUDY DESIGN

Women scheduled for cesarean deliveries at our facility were included. Intraoperative blood loss was measured using the Triton, which was masked to the clinical team, as well as estimated by the surgeon (subjective estimated blood loss). The relation between the 2 methods (Triton and subjective estimated blood loss) and postoperative hemoglobin as well as delta hemoglobin (postoperative minus preoperative hemoglobin) was determined using the Spearman correlation. Triton measurement and subjective estimated blood loss were compared between women with delta hemoglobin in the upper quartile (cases) vs all other quartiles (control). Prediction of delta hemoglobin in the upper quartile also was evaluated for each method, and the area under the receiver operating characteristic curves was compared.

RESULTS

The trial enrolled 242 patients. The mean blood loss estimated by the Triton device was significantly lower than that estimated by clinical judgment (415.3±260.6 vs 799.6±215.6 mL, P<.01). The Triton estimate correlated best with delta hemoglobin. Seventy patients had delta hemoglobin in the upper quartile (delta hemoglobin ≥2). There was a significant difference in the Triton blood loss measurement between cases and controls but no difference with subjective estimated blood loss. Triton, but not subjective estimated blood loss, was predictive of delta hemoglobin ≥2 g/dL (Triton: area under the receiver operating characteristic curve, 0.66; 95% confidence interval, 0.58-0.74; P<.01 vs subjective estimated blood loss: area under the receiver operating characteristic curve, 0.53; 95% confidence interval, 0.45-0.61; P=.45).

CONCLUSIONS

The Triton system provides a better estimate of blood loss than the visual estimate. Clinical trials to evaluate its benefit are warranted.

Preoperative moderate thrombocytopenia is not associated with increased blood loss for low-risk cesarean section: a retrospective cohort study

BACKGROUND

The occurrence of thrombocytopenia is as high as 7-12% in pregnancy, yet minimum platelet count safe for cesarean section remains unknown.

METHODS

In this retrospective noninferior cohort study, we consecutively included patients undergoing cesarean section for a period of 6 years in a tertiary hospital and excluded patients at very high risk for excessive hemorrhage. The included patients with preoperative platelet count of 50-100 × 109/L were defined as the thrombocytopenic group. The control group were eligible patients with preoperative platelet count>150 × 109/L, matched to the thrombocytopenic group by age and operation timing in a 1:2 ratio. Mixed effect model was used to analyze the effect of thrombocytopenia based on a noninferiority assumption. The predefined noninferiority delta of bleeding was 50 mL.

RESULTS

There was no significant difference of the calculated blood loss between the thrombocytopenic and the control group (mean difference = 8.94, 95% CI - 28.34 mL to 46.09 mL). No statistical difference was observed in the requirement for blood transfusion, visually estimated blood loss, or the incidence of adverse events between groups. Although there were more patients admitted to intensive care unit (odds ratio = 12, 95% CI 2.69-53.62, p = 0.001) in the thrombocytopenic group, most of them required critical care for reasons other than hemorrhage. The thrombocytopenic group had longer length of hospital stay (mean difference = 0.40 days, 95% CI 0.09-0.71, p = 0.011), but the difference was considered as clinically insignificant.

CONCLUSIONS

Preoperative moderate thrombocytopenia is not associated with increased blood loss, blood transfusion, or occurrence of adverse events in patients undergoing cesarean section in absence of additional bleeding risk.

Management of post-partum hemorrhage and the role of the obstetric anesthesiologist

PURPOSE OF REVIEW

The landscape of post-partum hemorrhage management is rapidly changing. Modifications to definitions, bundles, and care plans occur frequently with management strategies becoming more complex. It has become apparent that the management of these patients requires a multidisciplinary approach with the involvement of obstetricians, anesthesiologists, gynecologist/oncologists, nursing, and care associates. This review article is meant to be an evidence-based review of post-partum hemorrhage with practical recommendations and a look at future directions of the management of post-partum hemorrhage from the vantage point of the obstetric anesthesiologist in an effort to enhance the collaborative treatment of this at risk population.

Postpartum hemorrhage: early identification challenges

Postpartum hemorrhage is the leading cause of maternal morbidity and mortality worldwide. The majority of maternal deaths associated with hemorrhage could be preventable. The accurate assessment of blood loss, identification of risk factors and timely recognition of postpartum hemorrhage remain major challenges in obstetrics. It is important to review available modalities for estimation and quantification of peripartum blood loss, the value of risk assessment tools as well as the challenges in early recognition of clinical signs and symptoms of postpartum hemorrhage.