Objective: To measure intra-operative blood loss at elective lower segment caesarean section and to compare estimated with 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 greater than 600 ml. One patient received a blood transfusion and another had a post-operative haemoglobin level less than 10.0 g/dl.
Conclusion: Blood loss at elective lower segment caesarean section was usually less than 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.