OBJECTIVE Our objective is to evaluate ultrasound differences in uterine scar between techniques using extramucosal suturing and full thickness suturing of the uterine incision. METHODS A retrospective observational study included cases of primary cesarean section. At 6-week postpartum, we evaluated by endovaginal ultrasound two elements in the sagittal view: the thickness of the uterine scar and the surface of defect (niche). Hysterotomy sites closed using a running full-thickness technique including the uterine mucosa (group 1) were compared to hysterotomies operated by the same surgeon but with extramucosal suturing (group 2). The operator switched from the running suture technique to extramucosal in 2013. RESULTS The study included 241 patients (115 cases in group 1 that were compared to 126 cases in group 2). There were no significant differences in age or body mass index between the two groups. Cesarean scar and niche were detectable in the entire studied population. There was a significant difference in both uterine scar thickness (5.8 vs. 6.2 mm, p = 0.02) and the presence and size of the niche (49 vs. 40 mm2, p = 0.001) in transvaginal ultrasound performed at 6-week postpartum. CONCLUSIONS Extramucosal suturing of the uterine scar seems to be associated with a better outcome on the postpartum ultrasound evaluation. CONCLUSIONS · The technique for suturing the hysterotomy can be the source of healing changes.. · An extramucosal suturing of the uterus seems to give a better aspect at the postpartum ultrasound.. · Decreasing the niche at cesarean scar may be beneficial for future pregnancies..