Blunt Expansion of Transverse Uterine Hysterotomy: Step-by-Step Technique
Blunt expansion of the transverse uterine hysterotomy should be performed using cephalad-caudad (vertical) finger separation rather than transverse (lateral) expansion, as this technique significantly reduces unintended extensions and surgical complications. 1, 2
Initial Uterine Incision
- Make a small transverse incision in the lower uterine segment using a scalpel, typically 2-3 cm in length, through the uterine wall until the amniotic cavity is entered 3
- The initial incision should be just large enough to allow insertion of fingers for subsequent expansion 4
Blunt Expansion Technique (Cephalad-Caudad Method)
Step 1: Insert the index fingers of both hands into the small transverse uterine incision 1, 2
Step 2: Separate your fingers in a cephalad-caudad direction (one finger moving upward toward the fundus, the other moving downward toward the cervix) rather than pulling laterally 1, 2
Step 3: Apply steady, controlled traction to expand the incision to approximately 10-12 cm or sufficient width to deliver the fetal head 1, 2
Step 4: Avoid forceful or rapid expansion that could cause uncontrolled extension 1, 2
Evidence Supporting This Technique
The cephalad-caudad expansion method demonstrates superior outcomes compared to transverse (lateral-lateral) expansion:
- Reduces unintended extensions by 50%: 3.7% with cephalad-caudad versus 7.4% with transverse expansion (P = 0.03) 1
- Decreases surgical complications: 11.53% with cephalad-caudad versus 16.42% with transverse expansion (OR 0.66; 95% CI 0.45-0.98; P = 0.04) 2
- Lowers risk of excessive blood loss: Blood loss >1500 mL occurred in 0.2% with cephalad-caudad versus 2.0% with transverse expansion (P = 0.04) 1
Blunt Versus Sharp Expansion
Blunt expansion is recommended over sharp extension with scissors to reduce surgical blood loss, which is the primary rationale endorsed by the Enhanced Recovery After Surgery Society 3, 5
However, the evidence shows equivalence in most outcomes:
- No significant difference in febrile morbidity (RR 0.86; 95% CI 0.70 to 1.05) 4
- Blunt expansion reduces mean blood loss by 55 mL (95% CI -79.48 to -30.52) and decreases transfusion need (RR 0.24; 95% CI 0.09 to 0.62) 4
- No difference in unintended extensions or duration of surgery between blunt and sharp methods 6
Common Pitfalls to Avoid
- Never use transverse (lateral-lateral) finger separation: This increases unintended extensions by approximately 100% compared to cephalad-caudad technique 1, 2
- Avoid sharp extension with scissors: While equivalent in safety to blunt expansion, it offers no advantage and the guideline recommendation favors blunt technique for blood loss reduction 3, 5
- Do not force expansion during early labor stages: Unintended extension risk correlates with labor stage (1.4% with no labor, 15.5% in first stage, 35.0% in second stage) 6
Clinical Context
This technique is part of evidence-based cesarean delivery modifications that collectively reduce wound complications when adopted as a bundle 3. The moderate-quality evidence supporting blunt expansion carries a weak recommendation grade, but the cephalad-caudad direction has stronger support from recent randomized trials 3, 1, 2.