Validation of a laboratory method of measuring postpartum blood loss.

Laboratory methods give more accurate measurement of blood loss in the postpartum period than visual estimation. In order to evaluate a laboratory method used to quantify blood loss postpartum, blood lost at gynecological operations was collected in a measuring bottle. The measured amount of blood (50-1,000 ml) was then poured onto absorbent paper towels and sanitary pads, in order to mimic conditions when measuring blood loss in clinical trials in the postpartum period. The amount of blood absorbed onto the absorbent paper and sanitary pads was measured by a rapid method of automatic extraction and photometric measurement of alkaline hematin. The study shows that the method provides a reliable and accurate means of measuring blood loss. The error in each case was less than 10% with an intraclass correlation coefficient of almost 1.