What is the risk of uterine rupture in a patient with a previous Cesarean Section (CS) who is now 5 weeks pregnant, without attempting a Vaginal Birth After Cesarean (VBAC)?

From the Guidelines

The risk of uterine rupture for a patient who had a cesarean section (CS) 5 months ago and is now 5 weeks pregnant is approximately 0.45% to 2.5%, even without attempting a vaginal delivery, as reported in a recent study 1. This risk exists because the uterine scar may not have fully healed and regained its strength. The patient should be closely monitored throughout pregnancy with regular ultrasounds to assess the cesarean scar thickness and integrity.

Key Considerations

• The patient's short interpregnancy interval of 5 months increases the risk of uterine rupture, as the recommended minimum interval between a cesarean delivery and subsequent pregnancy is 18-24 months to allow for complete healing of the uterine scar.
• A systematic review reported the absolute risk of uterine rupture in vaginal birth after caesarean section was 0.87% and after planned repeat caesarean section was 0.09% 1.
• Management should include consideration of scheduled repeat cesarean delivery prior to the onset of labor, ideally at 36-37 weeks after fetal lung maturity is confirmed.
• Antenatal corticosteroids (betamethasone 12mg IM, two doses 24 hours apart) should be administered if delivery is planned before 39 weeks to reduce neonatal respiratory complications.

Monitoring and Counseling

• The patient should be counseled about warning signs of uterine rupture including severe abdominal pain, vaginal bleeding, and signs of shock.
• Regular ultrasounds should be performed to assess the cesarean scar thickness and integrity.
• The patient's risk factors, values, and preferences should be considered when discussing possible labor and vaginal birth after cesarean delivery 1.

From the Research

Uterine Rupture Risk Without Attempting Vaginal Delivery

The patient in question had a cesarean section (CS) in October and is now 5 weeks pregnant, 5 months later. To assess her risk of uterine rupture without attempting a vaginal delivery, we can look at the risk associated with elective repeat cesarean delivery without labor.

• The risk of uterine rupture for elective repeat cesarean delivery (without labor) is reported to be 0.02% (4 of 17,714) 2.
• Indicated repeat cesarean delivery (with or without labor) has a higher risk of uterine rupture, at 0.12% (7 of 6,080) 2.
• The overall risk of uterine rupture for women with a prior CS is low, at 0.32% (125 of 39,117) 2.
• The presence of labor increases the risk of uterine rupture, even in the absence of an indication for cesarean delivery (0.15% vs 0%, P < 0.01) 2.

Factors Influencing Uterine Rupture Risk

Several factors can influence the risk of uterine rupture, including:

• Previous vaginal delivery, which is a protective factor against uterine rupture 3, 4.
• Multiple prior cesareans, short interpregnancy interval, single-layer uterine closure, prior preterm cesarean, labor induction, and augmentation, which may increase the risk of uterine rupture 5.
• The type of uterine incision and the presence of other medical conditions may also affect the risk of uterine rupture.

Clinical Implications

Given the low risk of uterine rupture associated with elective repeat cesarean delivery without labor, this option may be considered for the patient in question. However, it is essential to individualize the approach based on the patient's specific medical history, preferences, and circumstances. Close monitoring and careful management are crucial to minimize the risk of uterine rupture and ensure the best possible outcomes for both the mother and the baby 6.