Correlation between the cervical length and the amount of bleeding during cesarean section in placenta previa.

Aim: To investigate the association between the amount of bleeding during a cesarean section and the effacement of the uterine cervix in patients with placenta previa. Methods: This study reviewed 115 singleton pregnancies with placenta previa. In cases of placenta previa, the thickness of the uterine muscle and cervical length were retrospectively measured and compared with the amount of bleeding during the cesarean section. Results: No correlation was found between the amount of bleeding during the cesarean operation and the thickness of the uterine isthmus. There was a significantly negative correlation between the amount of bleeding and cervical length (r = -0.344, P < 0.001). The threshold cervical length associated with massive bleeding (> 2500 mL) was 25 mm, based on an ROC curve. The relative risk for massive bleeding in cases with a short cervical length (< 25 mm) was 7.2 (95% CI, 2.3-22.3) in comparison to cases with a long cervical length. Conclusions: This study demonstrated that a short cervical length in cases with placenta previa was associated with massive bleeding during the operation. Short cervical length seems to be one of the warning signs for massive bleeding during the operation for placenta previa.