The influence of gender and professional background on the accuracy of visual blood loss estimation in obstetrics: a prospective observational simulation study

The influence of gender and professional background on the accuracy of visual blood loss estimation in obstetrics: a prospective observational simulation study | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 18 March 2026 V1 Latest version Share on The influence of gender and professional background on the accuracy of visual blood loss estimation in obstetrics: a prospective observational simulation study Authors : Maximilian Niederer , Mathias Bader , Chiara Archam , Sascha Hammer , Sebastian Labenbacher , Helmar Bornemann-Cimenti 0000-0002-1201-3752 , Lioba Heuschneider 0009-0002-7510-3330 [email protected] , and Philipp Zoidl 0000-0001-7643-3193 Authors Info & Affiliations https://doi.org/10.22541/au.177383013.36748707/v1 118 views 46 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Objective: Accurate visual estimation of blood loss is critical for early recognition of obstetric haemorrhage. Despite its widespread use, visual estimation is prone to substantial bias. While professional experience has been shown to influence estimation accuracy, the potential contribution of gender-associated visual perceptual differences remains insufficiently explored . Design: We carried out a prospective observational simulation-based study at a tertiary university medical centre in Graz, Austria Setting/Sample: 50 physicians (28 females/22 males) were recruited from anaesthesiology and obstetrics. Eligibility required at least three months of clinical experience in obstetrics or obstetric anaesthesia. Clinicians with known colour-vision deficiency were excluded. Methods: All participants visually estimated blood loss in four simulated obstetric scenarios. The blood volumes and haemoglobin concentrations were verified by volume measurement and point of care testing. Each scenario was viewed individually under standardized conditions without access to physiological or contextual clinical information. Main Outcome Measures The primary outcome was absolute estimation error (mL) according to gender or professional background of participants. Secondary outcomes included scenario-specific accuracy and the association between self-rated confidence and estimation accuracy. Results: Women outperformed men in low and moderate volume scenarios. Across all scenarios the overall difference median absolute estimation error did not reach statistical significance. Professional background showed a stronger effect than gender: gynaecologists were significantly more accurate than anaesthetists across most scenarios (p < 0.001). Conclusions: Visual blood loss estimation accuracy in obstetric simulations is influenced by both gender and professional background. Gender-related differences appear volume-dependent, whereas professional experience exerts a consistent influence. Maximilian Niederer* a , Mathias Bader* a , Chiara Archam a ; Sascha Hammer a ; Sebastian Labenbacher a ; Helmar Bornemann-Cimenti a ; Lioba Heuschneider a +; Philipp Zoidl a *These authors contributed equally to this work From the a Department of Anaesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria +Address correspondence to: Lioba Heuschneider, Department of Anaesthesiology and Intensive Care Medicine, Medical University of Graz, Auenbruggerplatz 5, 8036 Graz, Austria, +43 316385 80139, (email: [email protected] ) Short Title: Gender and visual blood loss estimation in obstetrics Objective: Accurate visual estimation of blood loss is critical for early recognition of obstetric haemorrhage. Despite its widespread use, visual estimation is prone to substantial bias. While professional experience has been shown to influence estimation accuracy, the potential contribution of gender-associated visual perceptual differences remains insufficiently explored . Design: We carried out a prospective observational simulation-based study at a tertiary university medical centre in Graz, Austria Setting/Sample: 50 physicians (28 females/22 males) were recruited from anaesthesiology and obstetrics. Eligibility required at least three months of clinical experience in obstetrics or obstetric anaesthesia. Clinicians with known colour-vision deficiency were excluded. Methods: All participants visually estimated blood loss in four simulated obstetric scenarios. The blood volumes and haemoglobin concentrations were verified by volume measurement and point of care testing. Each scenario was viewed individually under standardized conditions without access to physiological or contextual clinical information. Main Outcome Measures The primary outcome was absolute estimation error (mL) according to gender or professional background of participants. Secondary outcomes included scenario-specific accuracy and the association between self-rated confidence and estimation accuracy. Results: Women outperformed men in low and moderate volume scenarios. Across all scenarios the overall difference median absolute estimation error did not reach statistical significance. Professional background showed a stronger effect than gender: gynaecologists were significantly more accurate than anaesthetists across most scenarios (p < 0.001). Conclusions: Visual blood loss estimation accuracy in obstetric simulations is influenced by both gender and professional background. Gender-related differences appear volume-dependent, whereas professional experience exerts a consistent influence. Funding: None Keywords: Blood Loss, Surgical; Postpartum Hemorrhage; Sex Characteristics; Hemorrhage/diagnosis; Clinical decision making; Introduction Accurate estimation of blood loss in obstetrics is essential for timely recognition and management of obstetric haemorrhage, one of the leading global causes of maternal morbidity and mortality. Clinicians worldwide rely on estimated blood loss (EBL) to guide critical decisions, including thresholds for transfusion, fluid management strategies, and activation of postpartum haemorrhage (PPH) protocols. Visual estimation remains the most commonly used method worldwide, even though extensive evidence shows that it is prone to inaccuracy and bias. Research shows patterns of underestimation at low volumes and overestimation at high volumes. 1-3 Obstetric environments further complicate visual estimation because blood often mixes with amniotic fluid, irrigation solutions and other serosanguinous fluids, altering visual appearance. 4 An emerging area of interest concerns how gender-related differences in visual and perceptual processing may influence EBL accuracy. Although the literature addressing gender differences in perceptual accuracy remains limited, some evidence about visual cognition demonstrates that women and men may process visual information in systematically different ways. Differences have been documented in contrast sensitivity, fine-grained colour discrimination, luminance processing, and susceptibility to visual illusions. 5 Experimental findings indicate that gender-related variation extends to visuospatial memory integration and the reconstruction of complex visual scenes, particularly when interpretation of subtle cues is required. 6 These perceptual distinctions suggest that gender could contribute to variation in clinically relevant tasks such as visual blood-loss estimation. 7 Despite these theoretical hints, gender-specific differences in EBL accuracy have received little attention in previous research. Professional background represents another important yet insufficiently explored factor potentially influencing EBL accuracy. Existing research demonstrates that obstetric surgeons tend to outperform clinicians who rely less on visual cues, such as anaesthetists, who typically integrate physiological parameters into their assessment. 2 Simulation studies support these observations, showing that estimation accuracy varies by specialty; however, none has explored whether gender interacts with professional background. 8,9 A more nuanced understanding of clinician characteristics that affect perceptual judgement could strengthen interdisciplinary communication, support earlier recognition of haemorrhage, and help reduce delays in escalation of care. The present study addresses these gaps by systematically examining gender differences in visual blood-loss estimation across four obstetric haemorrhage simulation scenarios. Gender was conceptualized as the primary variable of interest, with professional background assessed as a secondary factor. By evaluating clinician performance across both low- and high-volume bleeding scenarios (as different bleeding volumes may emphasize different aspects of visual processing), the study aimed to identify when gender-related differences are most pronounced. Methods Study design and ethical considerations This prospective observational simulation study was conducted at the Medical University of Graz in November 2025. Simulations were done on the 05.11.2025. The study followed institutional guidelines for human research, complied with the Declaration of Helsinki, and received ethical approval from the institutional review board (IRB number 1269/2025) of the Medical University of Graz on 03.11.2025. All participants provided written informed consent prior to enrolment. Participants Fifty clinicians were voluntarily recruited from the departments of Anaesthesiology and Obstetrics & Gynaecology. Eligibility criteria required at least three months of clinical experience in operative obstetrics or obstetric anaesthesia. Individuals with known color-vision deficiency were excluded. Sample size was based on an a priori power analysis designed to detect a difference of 40 mL in estimated blood loss between female and male participants at a two-sided significance level of 5% and a power of 80%. These calculations resulted in 50 required participants, with equal group sizes. This sample size is consistent with previous simulation-based studies on visual blood-loss estimation, which have used comparable numbers of participants and demonstrated sufficient power to detect clinically meaningful differences. Simulation procedure Four standardized obstetric haemorrhage scenarios were created using mixtures of packed red blood cells and isotonic saline solution to simulate realistic intraoperative bleeding. True haemoglobin concentrations were verified using point-of-care blood gas analysis to ensure credible colour and dilution profiles. Scenario characteristics: • Scenario 1 (Caesarean birth): true simulated blood loss 438 mL, Hb 10.9 g/dL; low-volume, dark, concentrated appearance representing early intraoperative bleeding • Scenario 2 (Ectopic pregnancy): true simulated blood loss 811 mL, Hb 9.4 g/dL; moderate-to-high volume, with brighter, diluted appearance mimicking mixed intraabdominal bleeding. • Scenario 3 (Placenta previa): true simulated blood loss 622 mL, Hb 8.6 g/dL; mid-range volume with moderate dilution • Scenario 4 (Postpartum haemorrhage): true simulated blood loss 1,014 mL, Hb 6.5 g/dL; high-volume, visually saturated appearance representing severe PPH. Simulated blood was presented in obstetric suction canisters and medical swabs commonly used during obstetric operations. Each participant viewed all four scenarios individually under standardized indoor lighting. From a viewing distance of 1,50 m, participants had 15 seconds to visually estimate blood loss. No hemodynamic parameters or additional contextual information were provided, ensuring reliance solely on visual assessment. The order of the scenarios was random, and the scenarios were shuffled between participants. Pictures of each set up provided can be viewed in the supplementary material. Outcome measures The primary outcome was the absolute estimation error in mL (absolute difference between visually estimated and true blood volume in the simulated scenario). Secondary outcomes included: • scenario-specific estimation accuracy • direction of error (underestimation vs. overestimation) • variability in estimation patterns (interquartile range) • exploratory subgroup analyses: gender, professional background, menstrual status, age, years of experience Gender was the primary independent variable. Professional background (anaesthesiology vs. gynaecology) was evaluated as a secondary predictor. Statistical analysis Analyses were performed using IBM SPSS Statistics Version 29. Normality of continuous variables was assessed using Kolmogorov-Smirnov and Shapiro-Wilk tests. As absolute estimation errors were non-normally distributed, non-parametric tests were applied. Between-group comparisons used Mann-Whitney U tests for continuous variables and chi-square tests for categorical variables. Descriptive statistics are presented as medians and IQR unless indicated otherwise. Statistical significance was defined as p < 0.05 (two-sided). Subgroup analyses were exploratory, with no correction for multiple testing. Results A total of 50 clinicians participated in the study, including 28 women (55%) and 22 men (45%). Professional backgrounds were evenly distributed, with 25 anaesthetists and 25 gynaecologists participating. Median clinical experience was 6.0 years (IQR 7.5) indicating a mix of early-career and more experienced clinicians. Female participants were additionally asked to report menstrual status: 23 women (82%) reported currently undergoing a menstrual cycle. Mean self-rated confidence in visual blood-loss estimation across all four scenarios was 2.6 ± 1.0 on a 5-point Likert scale, suggesting moderate perceived certainty. Baseline characteristics are summarized in Table 1. Gender differences in estimation accuracy across scenarios Across all four scenarios combined, women demonstrated lower median absolute estimation errors than men. Although this overall gender difference did not reach conventional statistical significance (Mann-Whitney U = 216.0, p = 0.072). The distribution of errors differed meaningfully between groups. Women showed a narrower interquartile range and fewer high-error outliers, indicating more consistent and tightly clustered performance. In contrast, male participants displayed greater dispersion of error values and several extreme overestimation episodes. Figure 1 provides a detailed overview of gender-specific estimation accuracy for each of the four simulation scenarios separately. • Scenario 1 (low volume): Women estimated blood loss significantly more accurately than men, with lower median errors (88 mL vs 225 mL; median absolute error female vs male) and a visibly narrower spread. This scenario, representing early intraoperative haemorrhage with relatively small volume, showed the clearest gender separation. • Scenario 2 (intermediate-high volume): Gender differences in this scenario were smaller and not as pronounced as in Scenario 1 (211 mL vs 311 mL; median absolute error female vs male). Both women and men showed increased variability compared with the low-volume condition. • Scenario 3 (moderate volume) Women demonstrated superior accuracy, with lower median errors and fewer outliers (150 mL vs 300 mL; median absolute error female vs male). This scenario combined moderate volume with mixed visual characteristics. • Scenario 4 (high volume): There was no significant gender variability in this scenario (375 mL vs 350 mL; median absolute error female vs male). Women and men showed converging median error values indicating that gender-related performance differences were less apparent at high blood-loss volumes. In summary, these findings suggest that gender differences in visual blood-loss estimation are most pronounced under low- and moderate-volume conditions (Scenarios 1 and 3), while performance becomes more similar between women and men as bleeding volume increases (Scenario 4). Effect of professional background on overall accuracy Professional background exerted a stronger and statistically robust influence on estimation accuracy than gender. When all four scenarios were pooled, gynaecologists significantly outperformed anaesthetists. Gynaecologists had lower median absolute estimation errors and considerably less variability in their performance compared with anaesthetists (Mann-Whitney U = 126.0, p < 0.001). Across all scenarios combined, gynaecologists demonstrated a more compact distribution of absolute estimation errors, characterized by lower median values, a narrower interquartile range, and only a small number of moderate outliers. In contrast, anaesthetists showed a markedly wider dispersion of errors, including several extreme values indicative of substantial overestimation. These large deviations were primarily driven by performance in the higher-volume scenarios, where absolute estimation errors were frequently pronounced. Scenario-specific analyses supported this overall pattern. Gynaecologists were significantly more accurate than anaesthetists in Scenarios 1, 3, and 4, with the largest divergence evident in Scenario 3, where female gynaecologists exhibited the lowest errors of all subgroups and male anaesthetists the highest. These scenario-specific comparisons are summarized in Table 2 . Confidence-accuracy relationship by gender At the cohort level, self-rated confidence in visual blood-loss estimation showed only a weak and statistically non-significant association with mean absolute estimation error (Spearman ρ = 0.215, p = 0.129). However, when the analysis was stratified by gender, a strikingly different pattern emerged. Figure 2 illustrates the relationship between self-rated confidence and absolute estimation error separately for women and men. Each data point represents an individual participant, with their cumulative absolute estimation error in mL of all four scenarios on the y-axis and confidence ratings averaged across all four scenarios on the 5-point Likert scale on the x- axis. These parameters reflect overall perceived certainty and overall estimation accuracy. Among female participants, confidence was not associated with estimation accuracy (Spearman ρ = −0.016, p = 0.934). In contrast, among male participants, higher confidence was significantly associated with larger estimation errors (Spearman ρ = 0.430, p = 0.046). This gender-specific discrepancy reflects a calibration gap: women’s confidence levels appeared well aligned with their actual performance, while men tended to be overconfident, particularly at higher levels of self-rated certainty. Subgroup analyses and error-direction patterns Exploratory subgroup analyses found no significant association between estimation accuracy and menstrual cycle status, age, or years of clinical experience. Women who reported current menstruation cycles did not differ significantly from those with no cycle in terms of absolute error. Similarly, greater years of clinical experience were not associated with improved estimation accuracy overall. There was, however, a non-significant tendency for more experienced anaesthetists to show somewhat larger overestimations, although this trend did not reach statistical significance. Error-direction analysis examined whether clinicians systematically underestimated or overestimated blood loss across scenarios. The observed pattern was consistent with previously described volume-dependent biases in visual blood-loss estimation. In low-volume scenarios, underestimation predominated across all participants, reflecting the well-known tendency to visually underrate smaller quantities of blood. In contrast, overestimation became more prominent in high-volume scenarios, particularly in Scenario 4. This effect was most pronounced among anaesthetists, who frequently produced large positive deviations from the true blood-loss volume. Discussion Main Findings This study examined how gender and professional background influence the accuracy of visual blood-loss estimation across four standardized obstetric haemorrhage simulations. The findings demonstrate that gender-related differences emerge primarily in low- and moderate-volume scenarios, whereas professional background exerts a consistent and robust influence across all bleeding conditions. Women estimated blood loss more accurately than men in two of the four scenarios, particularly when tasks required discrimination of subtle visual cues. Gynaecologists consistently outperformed anaesthetists and displayed substantially lower variability in estimation errors. Interpretation The observation that women performed more accurately in low-volume conditions aligns with evidence from science demonstrating gender differences in fine-grained visual perception and processing. Prior research shows that women outperform men in contrast sensitivity, color discrimination, and detection of subtle luminance gradients, skills that may be especially important in early or less pronounced bleeding where visual signals are less salient. 5,7 Scenario 1 and 3 exemplify this pattern, with women demonstrating both lower errors and tighter clustering of estimates. In high-volume settings, gender differences diminished. In Scenario 4, women and men showed nearly overlapping estimation performance. One plausible explanation is visual saturation: as blood volume increases, the perceptual challenge shifts from interpreting fine visual details to judging large fluid collections. Under such conditions, clinicians, irrespective of gender, may rely on global heuristics rather than subtle visual cues. Existing literature notes that both men and women tend to apply size-based heuristics when interpreting large volumes, often resulting in overestimation. 3 Professional background emerged as a stronger predictor of estimation accuracy than gender. Gynaecologists produced consistently lower errors across nearly all scenarios. Their narrower error distributions suggest a more uniform perceptual calibration, likely developed through repeated intraoperative exposure to obstetric bleeding. This finding is consistent with prior simulation and clinical studies indicating that obstetricians and surgeons outperform clinicians whose practice relies less on direct visual blood assessment. In contrast, anaesthetists generally depend on physiological indicators such as hemodynamic changes and laboratory values. The absence of such cues in this simulation environment may have contributed to their wider variability of estimates. The error-direction patterns further support these interpretations. Women demonstrated balanced tendencies for under- and overestimation in low-volume settings, while men more often underestimated small volumes. Anaesthetists, meanwhile, showed substantial overestimation in high-volume scenarios. These volume-dependent biases are well-documented in the literature and likely reflect a combination of visual dilution and expectation-driven heuristics. 2,8,9 Exploratory subgroup analyses found no association between estimation accuracy and menstrual status, age, or years of experience. Although hormonal fluctuations have been shown to influence attentional or visuospatial performance in some controlled experiments, our findings indicate no clinically meaningful effect in visual blood-loss estimation. Similarly, years of professional experience did not correlate with improved accuracy overall. The tendency toward greater overestimation among more experienced anaesthetists may reflect increased vigilance or risk-averse practice, rather than improved perceptual accuracy. The relationship between confidence and performance offers additional insight into gender-related patterns in clinical perception. At overall cohort level, confidence was not associated with accuracy. However, gender-stratified results revealed marked differences: women displayed well-calibrated metacognition, with confidence levels closely reflecting actual performance. In contrast, men showed a positive correlation between confidence and error, indicating overconfidence. This phenomenon is consistent with previous literature showing that male clinicians often exhibit higher self-assessed certainty which does not reliably predict performance in diagnostic and procedural tasks. 1,7,10 Clinical implications Our findings underscore that there is risk of overconfidence with visual blood loss estimation which may delay escalation during haemorrhage when clinicians overestimate the accuracy of their assessments. Individualized feedback during simulation may help mitigate these behaviours. 11 Targeted simulation-based training seems especially important for clinicians with limited visual exposure to obstetric bleeding and may help reduce estimation errors and improve situational awareness. Incorporating feedback mechanisms that strengthen perceptual calibration and address overconfidence may further enhance the accuracy of haemorrhage assessment. 12 Strengths and limitations This study has several strengths, including balanced gender and professional representation, controlled presentation of realistic haemorrhage scenarios, verified haemoglobin concentrations, and standardized viewing conditions. The methodology allows direct examination of gender or profession specific perceptual influences. Nonetheless, limitations must be acknowledged. Simulations cannot fully replicate the complexity of real obstetric haemorrhage, where visual cues interact with dynamic bleeding, tissue appearance, and changing vital signs. The absence of physiological information in this simulation may disadvantage certain professional groups, particularly anaesthetists. Furthermore, although the sample size is comparable to other simulation studies, it may have limited our ability to detect smaller gender effects. Finally, findings may not generalize across institutions with different training practices or visual exposure to obstetric haemorrhage. Conclusion This simulation-based study demonstrated that both gender and professional background influence the accuracy of visual blood-loss estimation. Women showed higher accuracy than men in low- and moderate-volume scenarios. Professional background proved an even stronger determinant of accuracy: gynaecologists consistently outperformed anaesthetists across nearly all scenarios and exhibited markedly less variability, indicating more reliable perceptual calibration gained through repeated clinical exposure to obstetric bleeding. These findings underscore that visual blood-loss estimation is influenced by a combination of perceptual abilities and experiential familiarity. Our results highlight the importance of interdisciplinary communication during haemorrhage management. Improving clinical safety in obstetric haemorrhage requires an interdisciplinary approach that accounts for systematic performance differences between clinician groups. Targeted simulation training strategies could help to address both gender-related and profession-related perceptual biases. Overall, integrating these insights into obstetric training and team communication practices may contribute to more effective and timely management of obstetric haemorrhage. Acknowledgments: None. Disclosure of Interests: None Contribution to Authorship: M.N.: Conceptualization, Methodology, Formal Analysis, Investigation, Writing—Original Draft; M.B.: Methodology, Writing—Original Draft; C.A.: Formal Analysis, Writing—Review & Editing; S.H.: Writing—Review & Editing, Project Administration; S.L.: Writing—Review & Editing, Project Administration; H.B-C.: Writing—Review & Editing, Supervision; L.H.: Conceptualization, Investigation, Writing—Original Draft, Writing— Review & Editing; P.Z.: Conceptualization, Investigation, Resources, Writing—Review & Editing, Supervision Details of Ethics Approval: The study followed institutional guidelines for human research, complied with the Declaration of Helsinki, and received ethical approval from the institutional review board (IRB number 1269/2025) of the Medical University of Graz on 03.11.2025 Funding: None received; References 1. Rothermel LD, Lipman JM. Estimation of blood loss is inaccurate and unreliable. Surgery. 2016 Oct;160(4):946–53. 2. Gerdessen L, Meybohm P, Choorapoikayil S, Herrmann E, Taeuber I, Neef V, et al. Comparison of common perioperative blood loss estimation techniques: a systematic review and meta-analysis. J Clin Monit Comput. 2021 Apr;35(2):245–58. 3. Stoker AD, Binder WJ, Frasco PE, Morozowich ST, Bettini LM, Murray AW, et al. Estimating surgical blood loss: A review of current strategies in various clinical settings. SAGE Open Medicine. 2024 Jan;12:20503121241308302. 4. Sheldon W, Blum J, Vogel J, Souza J, Gülmezoglu A, Winikoff B, et al. Postpartum haemorrhage management, risks, and maternal outcomes: findings from the World Health Organization Multicountry Survey on Maternal and Newborn Health. BJOG. 2014 Mar;121(s1):5–13. 5. Shaqiri A, Roinishvili M, Grzeczkowski L, Chkonia E, Pilz K, Mohr C, et al. Sex-related differences in vision are heterogeneous. Sci Rep. 2018 May 14;8(1):7521. 6. Qian Y, Berenbaum SA, Gilmore RO. Vision contributes to sex differences in spatial cognition and activity interests. Sci Rep. 2022 Oct 21;12(1):17623. 7. Lawton CA, Hatcher DW. Gender Differences in Integration of Images in Visuospatial Memory. Sex Roles. 2005 Nov;53(9–10):717–25. 8. Athar MW, Abir G, Seay RC, Guo N, Butwick A, Carvalho B. Accuracy of visual estimation of blood loss in obstetrics using clinical reconstructions: an observational simulation cohort study. International Journal of Obstetric Anesthesia. 2022 May;50:103539. 9. Lemée J, Scalabre A, Chauleur C, Raia-Barjat T. Visual estimation of postpartum blood loss during a simulation training: A prospective study. Journal of Gynecology Obstetrics and Human Reproduction. 2020 Apr;49(4):101673. 10. Croskerry P. The Importance of Cognitive Errors in Diagnosis and Strategies to Minimize Them: Academic Medicine. 2003 Aug;78(8):775–80. 11. Papageorghiou AT, Kihara AB, Dunkley-Bent J, Ahsan S, Begum F, Escobar Vidarte MF, et al. New guidelines for the prevention, diagnosis, and treatment of postpartum haemorrhage: ending the geography of risk. The Lancet Global Health. 2025 Nov;13(11):e1796–8. 12. Picetti R, Miller L, Shakur-Still H, Pepple T, Beaumont D, Balogun E, et al. The WOMAN trial: clinical and contextual factors surrounding the deaths of 483 women following post-partum haemorrhage in developing countries. BMC Pregnancy Childbirth. 2020 Dec;20(1):409. Table/Figure Caption List: Table 1: Participants characteristics, professional background, clinical experience, and self-rated confidence. Table 2: Scenarios with clinical contexts and blood compositions Figure 1: Estimated blood loss provided by female (red) and male (white) participants across four clinical scenarios Figure 2: Scatterplot showing the association between self-rated confidence in visual blood-loss estimation (5-point Likert scale) and cumulative absolute estimation error (mL). Each point represents one participant. Confidence was averaged across all four simulation scenarios. Solid lines represent linear regression trends for each gender. Supplementary Material File (figure 1 estimated blood loss provided by female.docx) Download 147.07 KB File (figure 2.docx) Download 259.51 KB File (tables_bjog.docx) Download 16.01 KB Information & Authors Information Version history V1 Version 1 18 March 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords delivery: caesarean section general obstetrics labour: management maternal mortality obstetric haemorrhage risk management Authors Affiliations Maximilian Niederer Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Mathias Bader Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Chiara Archam Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Sascha Hammer Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Sebastian Labenbacher Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Helmar Bornemann-Cimenti 0000-0002-1201-3752 Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Lioba Heuschneider 0009-0002-7510-3330 [email protected] Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Philipp Zoidl 0000-0001-7643-3193 Landeskrankenhaus-Universitatsklinikum Graz Universitatsklinik fur Anasthesiologie und Intensivmedizin View all articles by this author Metrics & Citations Metrics Article Usage 118 views 46 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Maximilian Niederer, Mathias Bader, Chiara Archam, et al. 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