Accuracy of Blood Loss Determination after Vaginal Delivery: Visual Estimation versus Calibrated Measurement

Background: The ability to determine accurately, the blood loss during childbirth is of extreme importance in the diagnosis and management of primary postpartum haemorrhage (PPH).
Aims: In this study, we evaluate the effectiveness of visual estimation of blood loss, as a method of diagnosing primary postpartum haemorrhage.
Methodology: A cross-sectional study on 271 participants was conducted between April and October 2012, at the Komfo Anokye Teaching Hospital. Women who went through spontaneous vaginal delivery were monitored and blood loss after delivery was visually estimated and then measured with a graduated receptacle, up to 1 hour post-delivery. The paired t-test and Bland-Altman plot was used to compare outcomes of the two methods. P<0.05 was considered significant.
Results: Mean age of study participants was 27.7±5.7. As per visual estimation, most participants were reported to have lost <200 ml of blood (45.0%) as opposed to that of measured losses where most participants had lost between 200-500 ml of blood (48.7%). The mean measured blood loss was 306.09±218.39 ml against a 250±188.78 ml mean visually estimated blood loss (P < 0.0001). Prevalence of primary PPH as estimated with measured blood losses was 20.3% (55/271). Visual estimation, however gave a prevalence of 15.9% (43/271), an underestimation by 4.4%. A Bland-Altman plot showed a clinical bias large enough to cause significant differences in diagnosis of primary PPH.
Conclusion: This study adds to existing evidence that the visual estimation of blood loss in clinical settings underestimates losses and is not reliable. This can lead to misdiagnosis of primary PPH and thus an underestimation of the condition. Health care workers should therefore base diagnosis on calibrated measurement methods.