What is the recommended uterine incision for a cesarean section in a patient with a low‑lying lateral placenta?

Uterine Incision for Low-Lying Lateral Placenta at Cesarean Section

Use preoperative and/or intraoperative ultrasonography to precisely locate the placenta and make a transverse uterine incision that avoids cutting through the placental tissue—if the placenta is lateral, place your incision away from the placental edge, and if transverse lie or inability to avoid the placenta exists, consider a vertical incision. 1

Key Surgical Approach

The 2019 RCOG Green-top Guideline provides clear direction for managing low-lying placentas at cesarean section 1:

Primary Strategy: Avoid Cutting Through the Placenta

• Use ultrasound guidance (preoperative and/or intraoperative) to determine the exact placental location and identify the optimal site for uterine incision 1
• Avoiding incision through anterior placenta praevia after 24 weeks reduces maternal blood transfusion requirements (Evidence level 2) 1
• For a lateral placenta, this means placing your transverse incision on the side of the lower uterine segment where the placenta is NOT located

When Standard Transverse Incision Won't Work

Consider vertical skin and/or uterine incisions when:

• The fetus is in transverse lie and you need to avoid the placenta 1
• This is particularly important below 28 weeks of gestation 1
• The placental position makes a safe transverse incision impossible

Alternative Incision Technique

• A 'J'-shaped uterine incision has been shown in small retrospective studies to decrease intraoperative blood loss and facilitate fetal delivery in placenta praevia cases 1
• This may be considered when standard approaches are not feasible

Critical Intraoperative Management

If You Must Cut Through the Placenta

Immediately clamp the umbilical cord after fetal delivery to avoid excessive fetal blood loss 1

Prepare for Hemorrhage Control

Have these interventions ready:

• Intrauterine balloon tamponade (Bakri balloon, BT-Cath, or Sengstaken-Blakemore tube) with 75-88% success rates for controlling PPH 1
• Compression sutures (B-Lynch technique)
• Early surgical intervention rather than prolonged conservative measures 1
• Interventional radiology capabilities if available (transarterial embolization, balloon occlusion) 1

Common Pitfalls to Avoid

1. Don't blindly make a standard low transverse incision without first confirming placental location—cutting through placenta increases maternal bleeding significantly 1

2. Don't delay definitive hemorrhage control measures—if pharmacological measures fail, move quickly to tamponade and surgical techniques 1

3. Be aware that factors predicting Bakri balloon failure include: prior cesarean section, anterior placentation, thrombocytopenia/coagulopathy, and PPH >500 ml in first hour 1

4. Have adequate blood products immediately available—close liaison with transfusion services is essential, with rapid infusion and warming devices ready 1

Practical Algorithm

1. Preoperative ultrasound → Confirm placental location (lateral, anterior, posterior)
2. Intraoperative ultrasound → Verify exact placental borders before incision
3. For lateral placenta → Make low transverse incision on the opposite side from placental edge
4. If placenta unavoidable or transverse lie → Consider vertical incision
5. If placenta is transected → Immediate cord clamping
6. If hemorrhage occurs → Rapid escalation to tamponade/surgical techniques

This approach prioritizes maternal morbidity and mortality by avoiding unnecessary placental disruption while maintaining the benefits of a transverse incision when safely feasible.