Impact of uterine closure on residual myometrial thickness after cesarean: a randomized controlled trial

BACKGROUND: Incomplete healing of uterine scar after cesarean has been associated with adverse gynecological and obstetrical outcomes. Several studies reported that uterine closure at cesarean influences the healing of uterine scar and the risk of uterine rupture at subsequent pregnancies: the commonly used locked single-layer suture including the decidua being associated with a 4-fold increased risk of uterine rupture. However, data from randomized trials are lacking. OBJECTIVE: We sought to evaluate the impact of 3 techniques of uterine closure after cesarean delivery on uterine scar healing. STUDY DESIGN: This was a 3-arm 1:1:1 randomized study in women with singleton pregnancies undergoing elective primary cesarean delivery at >= 38 weeks' gestation. Closure of the uterine scar was carried out by locked single layer including the decidua, double layer with locked first layer including the decidua, or double layer with unlocked first layer excluding the decidua. Primary outcome was residual myometrial thickness (RMT) at the site of the scar, measured by transvaginal ultrasound 6 months after delivery. Secondary outcome was the RMT as a percentage of the myometrial thickness above the scar (healing ratio). Intent-to-treat analyses using Student t test were performed to compare each double-layer technique to the single-layer closure, and P < .025 was considered significant. RESULTS: Complete follow-up was obtained from 73 (90%) of the 81 participants. Compared to single-layer closure, double-layer closure with unlocked first layer was associated with thicker RMT (3.8 +/- 1.6 mm vs 6.1 +/- 2.2 mm; P < .001) and greater healing ratio (54 +/- 20% vs 73 +/- 23%; P = .004). In contrast, double-layer closure with locked first layer was not significantly different than single-layer closure in either RMT (4.8 +/- 1.3; P = .032) or healing ratio (60 +/- 21%; P = .287). CONCLUSION: Double-layer closure with unlocked first layer is associated with better uterine scar healing than locked single layer.