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Comparison of quantitative and calculated postpartum blood loss after vaginal delivery
Madar, H., Sentilhes, L., Goffinet, F., Bonnet, M. P., Rozenberg, P., Deneux-Tharaux, C.
American journal of obstetrics & gynecology MFM. 2023;:101065
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Editor's Choice
Abstract
BACKGROUND Because there is no consensual method of assessing postpartum blood loss, the comparability and relevance of the postpartum hemorrhage-related literature is questionable. Quantitative blood loss assessment using a volumetric technique with a graduated collector bag has been proposed to overcome limitations of intervention-based outcomes but remains partly subjective and potentially biased by amniotic fluid or missed out-of-bag losses. Calculated blood loss based on laboratory parameters has been published and used as an objective method expected to reflect total blood loss, but few studies have compared quantitative with calculated blood loss. OBJECTIVE This study aimed to compare the distribution of postpartum blood loss after vaginal delivery assessed by two methods - quantitative and calculated blood loss - and the incidence of abnormal blood loss with each method. STUDY DESIGN The data came from the merged database of 3 multicenter, randomized controlled trials, all testing different interventions to prevent postpartum blood loss in individuals with a singleton live fetus ≥ 35 weeks, born vaginally. All 3 trials measured blood loss volume by using a graduated collector bag. Hematocrit was measured in the eighth or ninth month of gestation and on day 2 postpartum. The two primary outcomes were: quantitative blood loss defined by the total volume of blood loss measured in a graduated collector bag, and calculated blood loss mathematically defined from the peripartum hematocrit change (estimated blood volume × [(antepartum hematocrit - postpartum hematocrit)/antepartum hematocrit], where estimated blood volume (mL) = booking weight (kg) × 85). We modelled the association between positive quantitative blood loss and positive calculated blood loss with polynomial regression and calculated the Spearman correlation coefficient. RESULTS Among the 8341 individuals included in this analysis, the median quantitative blood loss (100 mL, interquartile range 50-275) was significantly lower than the median calculated blood loss (260 mL, interquartile range 0-630) (P<.05). The incidence of abnormal blood loss was lower with quantitative blood loss than calculated blood loss for blood loss ≥ 500 mL, ≥ 1000 mL and ≥ 2000 mL, respectively, it was 9.6% (799/8341) vs 32.3% (2691/8341), 2.1% (176/8341) vs 11.5% (959/8341), and 0.1% (10/8341) vs 1.4% (117/8341); (P<.05). Quantitative blood loss and calculated blood loss were significantly but moderately correlated (Spearman coefficient=0.44; P<.05). The association between them was not linear, and their difference tended to increase with blood loss. Negative calculated blood loss values occurred in 23% (1958/8341) of individuals; among them, more than 99% (1939/1958) had quantitative blood loss ≤ 500 mL. CONCLUSION Quantitative and calculated blood loss were significantly but moderately correlated after vaginal delivery. However, clinicians should be aware that quantitative blood loss is lower than calculated blood loss, with a difference that tended to rise as blood loss increased.
PICO Summary
Population
Patients who gave birth vaginally, participating in the TRACOR, CYTOCINON, and TRAAP randomised controlled trials (RCTs) in several French maternity units (n= 8,341).
Intervention
This study aimed to compare the distribution of postpartum blood assessed by two methods - quantitative and calculated blood loss - and the incidence of abnormal blood loss with each method.
Comparison
Outcome
The data came from 3 RCTs testing different interventions to prevent postpartum blood loss. All 3 trials measured blood loss volume by using a graduated collector bag. The authors modelled the association between positive quantitative blood loss and positive calculated blood loss with polynomial regression and calculated the Spearman correlation coefficient. The median quantitative blood loss (100 mL, IQR= 50, 275) was significantly lower than the median calculated blood loss (260 mL, IQR= 0, 630). The incidence of abnormal blood loss was lower with quantitative blood loss than calculated blood loss. Quantitative blood loss and calculated blood loss were significantly but moderately correlated (Spearman coefficient= 0.44). The association between them was not linear, and their difference tended to increase with blood loss. Negative calculated blood loss values occurred in 23% (1,958/8,341) of individuals; among them, more than 99% (1,939/1,958) had quantitative blood loss ≤ 500 mL.
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The Recognition of Excessive blood loss At ChildbirTh (REACT) Study: A two-phase exploratory, sequential mixed methods inquiry using focus groups, interviews, and a pilot, randomised crossover study
Hancock A, Weeks AD, Furber C, Campbell M, Lavender T
BJOG : an international journal of obstetrics and gynaecology. 2021
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Editor's Choice
Abstract
OBJECTIVES To explore how childbirth-related blood loss is evaluated and excessive bleeding recognised; and develop and test a theory of postpartum haemorrhage (PPH) diagnosis. DESIGN Two-phase, exploratory, sequential mixed methods design using focus groups, interviews and a pilot, randomised crossover study. SETTING Two hospitals in North West England. SAMPLE Women (following vaginal birth with and without PPH), birth partners, midwives and obstetricians. METHODS Phase 1 (qualitative): 8 focus groups and 20 one-to-one, semi-structured interviews were conducted with 15 women, 5 birth partners, 11 obstetricians, 1 obstetric anaesthetist and 19 midwives (n=51). Phase 2 (quantitative): 11 obstetricians and 10 midwives (n=21) completed two simulations of fast and slow blood loss using a high-fidelity childbirth simulator. RESULTS Responses to blood loss were described as automatic, intuitive reactions to the speed, nature and visibility of blood flow. Health professionals reported that quantifying volume was most useful after a PPH diagnosis, to validate intuitive decisions and guide on-going management. During simulations, PPH treatment was initiated at volumes at or below 200ml (fast mean blood loss 79.6ml, SD 41.1; slow mean blood loss 62.6ml, SD 27.7). All participants treated fast, visible blood loss, but only half treated slow blood loss, despite there being no difference in volumes (difference 18.2ml, 95% CI -5.6 to 42.2ml, p=0.124). CONCLUSIONS Experience and intuition, rather than blood loss volume, inform recognition of excessive blood loss after birth. Women and birth partners want more information and open communication about blood loss. Further research exploring clinical decision-making and how to support it is required.
PICO Summary
Population
Women following vaginal birth, birth partners, midwives and obstetricians in two centres in the UK (n= 51).
Intervention
Simulation of ‘slow blood loss followed by fast blood loss’ (n= 10).
Comparison
Simulation of ‘fast blood loss followed by slow blood loss’ (n= 11).
Outcome
This mixed methods study had a qualitative phase involving focus groups and interviews, and a quantitative phase consisting in a randomised crossover study. Responses to blood loss were described as automatic, intuitive reactions to the speed, nature and visibility of blood flow. Health professionals reported that quantifying volume was most useful after a postpartum haemorrhage (PPH) diagnosis, to validate intuitive decisions and guide on-going management. During simulations, PPH treatment was initiated at volumes at or below 200ml (fast mean blood loss 79.6ml, SD 41.1; slow mean blood loss 62.6ml, SD 27.7). All participants treated fast, visible blood loss, but only half treated slow blood loss, despite there being no difference in volumes (difference 18.2ml).
3.
Techniques for blood loss estimation in major non-cardiac surgery: a systematic review and meta-analysis
Tran A, Heuser J, Ramsay T, McIsaac DM, Martel G
Canadian journal of anaesthesia = Journal canadien d'anesthesie. 2020
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Editor's Choice
Abstract
PURPOSE Estimated blood loss (EBL) is an important tool in clinical decision-making and surgical outcomes research. It guides perioperative transfusion practice and serves as a key predictor of short-term perioperative risks and long-term oncologic outcomes. Despite its widespread clinical and research use, there is no gold standard for blood loss estimation. We sought to systematically review and compare techniques for intraoperative blood loss estimation in major non-cardiac surgery with the objective of informing clinical estimation and research standards. SOURCE A structured search strategy was applied to Ovid Medline, Embase, and Cochrane Library databases from inception to March 2020, to identify studies comparing methods of intraoperative blood loss in adult patients undergoing major non-cardiac surgery. We summarized agreement between groups of pairwise comparisons as visual estimation vs formula estimation, visual estimation vs other, and formula estimation vs other. For each of these comparisons, we described tendencies for higher or lower EBL values, consistency of findings, pooled mean differences, standard deviations, and confidence intervals. PRINCIPLE FINDINGS We included 26 studies involving 3,297 patients in this review. We found that visual estimation is the most frequently studied technique. In addition, visual techniques tended to provide lower EBL values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses likely due to sample size limitations. When accounting for the contextual mean blood loss, similar case-to-case variation exists for all estimation techniques. CONCLUSIONS We found that significant case-by-case variation exists for all methods of blood loss evaluation and that there is significant disagreement between techniques. Given the importance placed on EBL, particularly for perioperative prognostication models, clinicians should consider the universal adoption of a practical and reproducible method for blood loss evaluation. TRIAL REGISTRATION PROSPERO (CRD42015029439); registered: 18 November 2015.PROSPERO (CRD42015029439); registered: 18 November 2015.
PICO Summary
Population
Adult patients undergoing major non-cardiac surgery (26 studies, n= 3,297).
Intervention
Visual estimation of blood loss.
Comparison
Formula estimation of blood loss, and other tecnniques for estimating blood loss.
Outcome
Visual estimation was the most frequently studied technique. Visual techniques tended to provide lower estimated blood loss values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses. When accounting for the contextual mean blood loss, similar case-to-case variation existed for all estimation techniques.