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.
In 47 women, the change in the uterine activity after the administration of a uterotonic agent was correlated with the amount of blood loss during the same period of time. Uterine activity was measured by a Gaeltec® catheter-tipped pressure transducer inserted transcervically within 5 min of delivery of the placenta. A uterotonic agent (either intravenous syntocinon, intramuscular syntometrine or oral misoprostol) was given after the insertion of the intrauterine pressure catheter and pressure recorded for another 90 min. Blood loss over the same 2-hour period was collected with absorbent paper which was then assessed by colorimetric measurement of the haemoglobin content in the sample. Our results show that the change in uterine activity is associated with the total blood loss. However, there is a poor linear correlation between the two variables probably because of the biological variation in myometrial activity and differences in coagulation mechanisms in normal women.
In 27 women, uterine activity in the third stage of labour was correlated with blood loss measured quantitatively during the same period of time. Myometrial activity was reflected by total intrauterine pressures measured using a Gaeltec® catheter tipped pressure transducer inserted transcervically within 5 min of delivery of the placenta. Blood loss over the same 2-hour period was collected on absorbent paper and measured in the laboratory by colorimetric measurement of the haemoglobin content. As total uterine activity in the third stage of labour decreases total blood loss increases, but there is a poor correlation of uterine activity to total blood loss over the same period of time, probably because of biological variations in myometrial activity in normal women.
A randomized controlled study of 112 women with singleton pregnancies at term, and no antenatal complications, admitted in spontaneous labour were randomized to receive either an intramuscular injection of 0.5 mg of Syntometrine or an intramuscular injection of 125 ug of prostaglandin 15-methyl F2 alpha at delivery of the anterior shoulder of the baby. Blood lost in the first 2 hours, and subsequent 22 hours postdelivery were collected separately and measured by colourimetric measurement of haemoglobin content. Other parameters in the third stage were measured, including need for transfusion of blood or blood products, length of the third stage, and change in haemoglobin concentration before and 24 hours after delivery. The incidence of side-effects with administration of either prostaglandin 15-methyl F2 alpha or Syntometrine were documented. The prophylactic use of intramuscular prostaglandin 15-methyl F2 alpha (Carboprost) in the active management of the third stage of labour gave similar results to prophylactic intramuscular Syntometrine in terms of length of the third stage of labour, incidence of postpartum haemorrhage and total blood loss in the first 2 hours and subsequent 22 hours after delivery. However it has the disadvantage of higher cost, as well as statistically significant increase in the incidence of profuse and frequent diarrhoea. Based on these results intramuscular injection of prostaglandin 15-methyl F2 alpha offers no advantage over intramuscular Syntometrine for routine prophylactic use to reduce blood loss in the third stage of labour.
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