Objective: The purpose of this study was to establish the validity of sonographic evaluation of lower uterine segment (LUS) thickness for complete uterine rupture.
Study design: A prospective cohort study of women with previous cesarean delivery was conducted. LUS thickness (full thickness and myometrial thickness only) was measured between 35 and 38 weeks gestation, and the thinnest measurement was considered to be the dependent variable. Receiver operating curve analyses and logistic regression were used.
Results: Two hundred thirty-six women were included in the study. Nine uterine scar defects (3 cases of complete rupture during a trial of labor and 6 cases of dehiscence) were reported. Receiver operating curve analyses showed that full thickness of <2.3 mm was the optimal cutoff for the prediction of uterine rupture (3/33 vs 0/92; P = .02). Full thickness was also identified as an independent predictor of uterine scar defect (odds ratio, 4.66; 95% confidence interval, 1.04-20.91)
Conclusion: Full LUS thickness of <2.3 mm is associated with a higher risk of complete uterine rupture.