Vaginal delivery after previous caesarean section: is X-ray pelvimetry necessary?

Area of Science:

• Obstetrics and Gynaecology
• Maternal-Fetal Medicine
• Radiology in Obstetrics

Background:

• Trial of labour after caesarean (TOLAC) is a common obstetric procedure.
• Accurate prediction of delivery mode is crucial for maternal and infant outcomes.
• The utility of antepartum X-ray pelvimetry (XRP) in guiding delivery decisions after a previous caesarean section remains debated.

Purpose of the Study:

• To evaluate the effectiveness of antepartum X-ray pelvimetry (XRP) in identifying women suitable for trial of labour or repeat caesarean section following one prior caesarean.
• To compare the outcomes of trial of labour with and without antepartum XRP.

Main Methods:

• A prospective controlled trial involving 306 women with a history of one previous caesarean section.
• Women were randomized to either an antepartum XRP group (at 36 weeks gestation) or a control group undergoing trial of labour without antepartum XRP.
• Mode of delivery, birthweight, and maternal/perinatal mortality and morbidity were assessed.

Main Results:

• The antepartum XRP group had a significantly lower vaginal delivery rate (16%) compared to the control group (42%).
• Among women with adequate antepartum XRP findings, only 27.7% had a vaginal delivery.
• Postpartum XRP in the control group revealed that 55% of women who delivered vaginally would have been recommended a caesarean section based on antepartum findings.

Conclusions:

• Antepartum X-ray pelvimetry is unnecessary and not recommended before a trial of labour in women with one previous caesarean section.
• Antepartum XRP increases the caesarean section rate and is an unreliable predictor of labour success.
• Clinical judgment and trial of labour are more effective in determining the mode of delivery.