Longitudinal transvaginal ultrasound evaluation of cesarean scar niche incidence and depth in the first two years after single‐ or double‐layer uterotomy closure: a randomized controlled trial

Cesarean deliveries are the most common abdominal surgery procedure globally, and the optimal way to suture the hysterotomy remains a matter of debate. The aim of this study was to assess the incidence of cesarean scar niches and the depth after single‐ or double‐layer uterine closure. Material and methods We performed a randomized controlled trial in which women were allocated to three uterotomy suture techniques: continuous single‐layer unlocked, continuous locked single‐layer, or double‐layer sutures. Transvaginal ultrasound was performed six weeks and 6–24 months after cesarean delivery [Clinicaltrials.gov ( NCT 02338388)]. Results The study included 435 women. Six weeks after delivery, the incidence of niche was not significantly different between the groups ( p = 0.52): 40% for single‐layer unlocked, 32% for single‐layer locked and 43% for double‐layer sutures. The mean ± SD niche depths were 3.0 ± 1.4 mm for single‐layer unlocked, 3.6 ± 1.7 mm for single‐layer locked and 3.3 ± 1.3 mm for double‐layer sutures ( p = 1.0). There were no significant differences ( p = 0.58) in niche incidence between the three groups at the second ultrasound follow up: 30% for single‐layer unlocked, 23% for single‐layer locked and 29% for double‐layer sutures. The mean ± SD niche depth was 3.1 ± 1.5 mm after single‐layer unlocked, 2.8 ± 1.5 mm after single‐layer locked and 2.5 ± 1.2 mm after double‐layer sutures ( p = 0.61). There was a trend ( p = 0.06) for the residual myometrium thickness to be thicker after double‐layer repair at the long‐term follow up. Conclusions The incidence of cesarean scar niche formation and the niche depth was independent of the hysterotomy closure technique.