A narrow pelvic outlet increases the risk for emergency cesarean section

Abstract

Background: The rate of cesarean section (CS) is increasing in Sweden as well as in most of the industrialized world. One of the most common indications for emergency CS is protracted labor. To what extent fetal pelvic disproportion is a cause of protracted labor is unclear. The value of pelvimetry has been questioned. The purpose of this study was to investigate whether women delivered with emergency CS because of protracted labor had a narrower pelvis than women delivered vaginally did.

Methods: Thirty women delivered with CS because of protracted labor comprised the study group. Thirty women vaginally delivered served as controls. The two groups were matched for gestational age, birth weight, and parity. The study group and the control group underwent an X-ray pelvimetry within 1 month of delivery.

Results: The study group and the control group did not differ in maternal age or body mass index. The mean birth weight was 3914 g in the study group and 3884 g in the control group. The mean pelvic outlet was 328 mm in the study group and 346 mm in the control group (P=0.0024). The mean pelvic inlet was 245 mm in the study group and 255 mm in the control group (P=0.0038).

Conclusion: A narrow pelvic outlet is associated with an increased risk of emergency CS because of protracted labor. A postpartum pelvimetry is recommended and should be used when to decide on route of delivery in forthcoming pregnancies.