This study by Vachon-Marceau et al. (AJOG, 2017) aimed to determine if there is a difference in lower uterine segment thickness depending on single or double-layer C-section uterine closure.
Prospective Cohort Study
There is an increased risk of uterine rupture during a trial of labor following C-section. Uterine thickness on ultrasound has been studied as a proxy for scar quality and risk of rupture in future pregnancies. In this study, 1,613 women underwent transabdominal and transvaginal ultrasounds in their third trimester to assess lower uterine segment thickness and scar defects resulting from previous C-section. The sonographers were blinded to clinical information. 495 (31%) women had previously underwent a single-layer and 1,118 (69%) had a double-layer closure. Women who had a double-layer closure had thicker lower uterine segments than women with single-layer closure with a difference of 0.11 mm (95% CI, 0.02-0.21 mm). Using multivariate logistic regression to account for variables, double-layer closure was less likely to result in a thin lower uterine segment thickness of < 2.0 mm (odds ratio 0.68; 95% CI, 0.51-0.90). Double-layer closure was also associated with a decreased risk of uterine scar defect with a relative risk of 0.32 (95% CI, 0.17 – 0.61) at birth. Type of thread (catgut vs. synthetic) used for closure had no impact on lower uterine thickness. The authors conclude that double-layer closure resulted in reduced risk of uterine segment thickness <0.2 mm and visible uterine scar defect on ultrasound in the third trimester.
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