Transvaginal Ultrasonographic Assessment of Lower Uterine Segment Thickness and Prediction of Uterine Rupture In Cases of Vaginal Birth After Caesarean Delivery

Abstract

Background : The rise in elective cesarean section (CSs), which make about one-third of all CS cases, is primarily to blame for the rise in the cesarean birth rate. Objective : To assess the strength of the association between transvaginal ultrasonographic measurement of the lower uterine segment (LUS) in women with prior one CS undergoing a trial of vaginal birth and uterine scar defect at delivery. Patients and methods : A retrospective observational study was conducted at Al-Ahrar Zagazig Teaching Hospital during the period from June 2018 through June 2020. The LUS thickness was measured through transvaginal ultrasonography in 60 gravidas (36 e 40 weeks) with previous one CS undergoing vaginal birth after cesarean, and the scar was evaluated during delivery. Results : Uterine dehiscence was found in four (6.7%) cases. There were no cases of uterine rupture. There was a signi fi cant correlation between the grade of scar and sonographic measurement of LUS thickness using transvaginal ultrasound ( P ¼ 0.001). The scar thickness in the third trimester (36 e 40 weeks) had a signi fi cant relation with the mode of delivery. LUS thickness of 2.4 mm was considered the critical cutoff value, above which safe vaginal delivery could be achieved. This critical cutoff value was derived from the receiver-operator characteristic curve with sensitivity, speci-fi city, positive predictive value, and negative predictive value of 75.0, 85.7, 27.3, and 98.0%, respectively. Conclusion : Measurement of the LUS thickness by transvaginal ultrasonographic seems to be a good screening test with its obviously high sensitivity and negative predictive values. LUS thickness of less than 2.4 mm is associated with a higher risk of uterine defect.