Risks for peroperative excessive blood loss in cesarean delivery.

Objective: To analyze risk factors for peroperative excessive blood loss at cesarean delivery.

Design: Case-control study.

Setting: Twenty-four of 26 maternity units in Norway with at least 500 expected deliveries per year.

Sample: A total of 2,778 women having singleton deliveries and participating in the Norwegian Breakthrough Project on Cesarean Section.

Methods: Elective and emergency operations were analyzed separately with extensive blood loss defined as hemorrhage > 1000 ml with controls defined as bleeding < 500 ml. All analyzes were done in SPSS (version 16.0) with chi-squared tests and logistic regression.

Main Outcome Measures: Adjusted odds ratios (aOR) of extensive peroperative bleeding.

Results: The prevalence of excessive blood loss differed between women undergoing elective (2.1%) and emergency cesarean deliveries (3.3%). Among maternal factors, chronic maternal diseases, pregnancy and delivery related conditions, placenta previa (aOR 19.7; 95% CI 5.4-72.2) and transverse lie (aOR 4.9; 95% CI 0.9-26.5) were the only risk factors for extensive blood loss in elective operations, whereas placenta previa (aOR 8.4; 95% CI 2.4-29.9), placental abruption (aOR 2.0; 95% CI 2.0-14.5), intervention at full cervical dilation (aOR 3.2; 95% CI 1.4-7.1) and high BMI (aOR 3.4; 95% CI 1.6-7.2) were risks in emergency operations.

Conclusion: The different risk pattern for excessive bleeding in cesarean deliveries should be recognized when planning available obstetric competence for surgery.