Ultrasound evaluation of the uterine scar after cesarean delivery: a randomized controlled trial of one- and two-layer closure.

OBJECTIVE: To survey the uterine scar thickness by ultrasonography in women randomly assigned to one- or two-layer hysterotomy closure after primary cesarean delivery. METHODS: This was a randomized, blinded trial of uterine scar closure with ultrasonographic follow-up. Thirty consecutive patients undergoing primary cesarean delivery were enrolled and randomly assigned to one- or two-layer closure of the hysterotomy. Ultrasound surveillance of the uterine scar thickness was performed at baseline (before surgery) and 48 hours, 2 weeks, and 6 weeks post partum. RESULTS: Patient compliance with the postpartum surveillance protocol was 90%, and the uterine scar was visualized in 99% of attempted ultrasonographic examinations. There were no differences between groups at baseline or at any of the follow-up evaluations. An initial 5- to 6-fold increase in uterine scar thickness was observed, followed by a gradual decrease with the 6-week measurements still thicker than baseline. Repeated measures analysis of variance showed significant variation across time points starting either at baseline (P<.001) or at 48 hour postoperatively (P<.001), but this variation did not depend on closure type (P=.79 for all visits and P=.81 beginning with 48-hour postoperative time point). CONCLUSION: The process of uterine scar remodeling can be successfully monitored by ultrasonography. Uterine scar thickness diminishes progressively after both one- or two-layer closure but does not vary with mode of hysterotomy closure. The uterine scar thickness remains increased even at 6 weeks post partum, suggesting that the process of uterine scar remodeling extends beyond the traditional postpartum period. CLINCAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00224250