An investigation into unexplained primary postpartum haemorrhage

Abstract

Postpartum haemorrhage remains a major problem in obstetrics, both nationally and internationally, since if bleeding is not controlled major organ failure may result, leading to maternal death or severe morbidity in the women who experience this traumatic event. Postpartum haemorrhage is defined as bleeding from, or into the genital tract after the birth of the baby up to the end of the puerperium, of 500 ml of blood or more, or any amount of blood loss that is deleterious to the health of the mother.
The incidence of postpartum haemorrhage varies from 6-20%, with rates varying between countries and between hospitals. The current incidence of postpartum haemorrhage in the collaborating unit is 14.2%, showing a gradual rise over the past 5 years. However, blood loss is notoriously underestimated, and it could be suggested that these figures are not fully representative of the incidence of postpartum haemorrhage.
The purpose of the study was to investigate primary postpartum haemorrhage in the absence of predisposing factors. There were two parts to the study. The first part of the study was exploratory in nature, and attempted to examine predisposing factors to postpartum haemorrhage in the collaborating unit, in the light of evidence from the literature. This part of the study involved 140 subjects who had a postpartum haemorrhage and 140 subjects who did not have a postpartum haemorrhage, who acted as a control group. There were two variables that appeared to be have some significance with regard to postpartum haemorrhage in this part of the study, namely, prolonged second stage of labour and birthweight of the baby >4000g. The study alsoappeared to accede to the findings of other authors, with regard to primigravidity, twin pregnancy and placental abruption, although no significance could be attached to these findings.
The second part of the study tested the hypothesis that it would be possible to predict atonic postpartum haemorrhage by the use of conventional uterine monitoring techniques. This part of the study involved 10 subjects who had a postpartum haemorrhage and 10 subjects who acted as controls. The methodology was by use of a retrospective case/control study, and involved examination of case notes and tocographic recordings taken in labour. Difficulties were encountered with regard to reliability of the research tool, and the accuracy of prediction of postpartum haemorrhage using this particular tool is therefore in doubt. In-depth examination of the case notes identified the numerous interventions that take place during labour, and led to the idea that in the absence of predisposing factors, primary postpartum haemorrhage may be associated with iatragenicity.
The findings from this study gave rise to the concept that in the absence of known predisposing factors, postpartum haemorrhage is due to a combination of factors, rather than one single factor.