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Postpartum blood loss: visual estimation versus objective quantification with a novel birthing drape.

INTRODUCTION
Immediate postpartum haemorrhage (PPH) is the most common cause of maternal mortality worldwide. Most recommendations focus on its prevention and management. Visual estimation of blood loss is widely used for the early detection of PPH, but the most appropriate method remains unclear. This study aimed to compare the efficacy of visual estimation and objective measurement using a sterile under-buttock drape, to determine the volume of postpartum blood loss.


METHODS
This study evaluated patients aged ≥ 18 years with low-risk term pregnancies, who delivered vaginally. Immediately after delivery, a birth attendant inserted the drape under the patient's buttocks. Postpartum blood loss was measured by visual estimation and then compared with objective measurement using the drape. All participants received standard intra- and postpartum care.


RESULTS
In total, 286 patients with term pregnancies were enrolled. There was a significant difference in postpartum blood loss between visual estimation and objective measurement using the under-buttock drape (178.6 ± 133.1 mL vs. 259.0 ± 174.9 mL; p < 0.0001). Regarding accuracy at 100 mL discrete categories of postpartum blood loss, visual estimation was found to be inaccurate, resulting in underestimation, with low correspondence (27.6%) and poor agreement (Cohen's kappa coefficient 0.07; p < 0.05), compared with objective measurement using the drape. Two-thirds of cases of immediate PPH (65.4%) were misdiagnosed using visual estimation.


CONCLUSION
Visual estimation is not optimal for measurement of postpartum blood loss in PPH. This method should be withdrawn from standard obstetric practice and replaced with objective measurement using the sterile under-buttock drape.