Measurements of the Lower Uterine Segment at Term in Women with Previous Cesarean Delivery

Purpose: To evaluate the accuracy of sonographic measurements of the lower uterine segment (LUS) thickness at term in predicting uterine scar defects in women with previous Cesarean delivery (CD). Methods: Eighty-nine pregnant women who underwent CD between 37 and 41 weeks of gestation from 2013 to 2015 were enrolled in this study and divided into two groups. Group A consisted of women with previous CD, and Group B consisted of women with previous vaginal deliveries. We performed an ultrasound evaluation of the myometrial and full thickness of LUS (mLUS and fLUS) transvaginally before a CD and evaluated the appearance of LUS during surgery, which was defined as follows: grade I, well-developed; grade II, thin without visible content; grade III, translucent with visible content; and grade IV, either dehiscence or rupture. Results: The median mLUS and fLUS were 1.50 and 4.07 mm in the group A, and 2.75 and 5.37 mm in the group B. We observed significant differences in the median mLUS and fLUS between grades I/II (2.07 and 4.37 mm) and grades III/IV (0.67 and 2.52 mm). Both mLUS and fLUS were predictive factors for grades III/IV and cutoff values were 0.97 mm of mLUS and 3.13 mm of fLUS, having a sensitivity of 87.5% and 75.0%, and a specificity of 87.7% and 91.4% in mLUS and fLUS measurement, respectively. Conclusion: Sonographic measurements of LUS at term may be a feasible and reliable method to predict uterine rupture or uterine dehiscence in women with prior CD.