Objective To measure intra-operative blood loss at elective lower segment caesarean section and to compare estimated wtih measured blood loss.
Design Prospective observational study. Blood loss was measured in patients who underwent lower segment caesarean section in the course of routine hospital activity.
Setting Tsan Yuk Hospital (Hong Kong), which is affiliated to the University of Hong Kong, 1990–1991.
Subjects Forty women (mean age 29 years) with singleton pregnancies (mean gestation 38 weeks) delivered by elective lower segment caesarean section under general anaesthesia (mean birthweight 3177 g).
Main outcome measure Intra-operative blood loss measured by the alkaline haematin method (intra-assay co-efficient of Variation 2.2%).
Results The mean measured blood loss was 487 ml (SE 40, range 164–1438). The mean estimated blood loss was 425 ml (SE 31) range 100–1300; mode 400). Observer error in estimating blood loss was higher if measured blood loss >600 ml. One patient received a blood transfusion and another had a post-operative haemoglobin level <10.0g/dl.
Conclusion Blood loss at elective lower segment caesarean section was usually <500 ml and was estimated with reasonable accuracy. However, there was a tendency to under-estimate blood loss when the measured loss exceeded 600 ml.