Background/aim: Cesarean section (CS) is a widely performed operation worldwide but data about uterine closure are lacking. We aimed to evaluate scar niches and compare single-layer and double-layer uterine closure at 6 months following CS.

Materials and methods: This prospective randomized trial assessed 56 women undergoing single- or double-layer uterine closure. None of the patients had previous uterine surgery and all CS cases were elective. Transvaginal ultrasound was performed 6 months after CS to assess the uterine scars by measuring the width, depth, and length of the scar niche and residual myometrial thickness. An experienced sonographer was blinded to the uterine closure technique and the ultrasounds were conducted by practitioners unaware of the technique in the postoperative follow-up appointments.

Results: Twenty-eight women were assigned to the single-layer closure group (Group 1) and 28 were assigned to the double-layer closure group (Group 2). The demographic and clinical characteristics of patients and the width, depth and diameter of the niche were similar between the groups, as was residual myometrial thickness. There was no difference in uterine scar volume under the incision between the two groups. The duration of surgery was approximately 5 min longer (p = 0.048) and hemoglobin decrease was about 0.5 g/dL less (p = 0.039) in the double-layer group compared to the single-layer group. Postmenstrual spotting rates were similar between the groups. Group 1 had two and Group 2 had one spontaneous pregnancy within 6 months after CS.

Conclusion: The single- and double-layer closure techniques do not produce different impacts on CS niche features at 6 months after delivery. Ultrasound might be an important noninvasive diagnostic tool for understanding CS scar remodeling.