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 CSs, which make about one-third of all CSs, 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 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 lower uterine segment thickness was measured transvaginal ultrasonography in 60 gravid as (36 week – 40 week) with previous one CS undergoing VBAC, and the scar was evaluated during delivery. Results: Uterine dehiscence was found in 4 cases (6.7%). There were no cases of uterine rupture. There was significant correlation between the grade of scar and sonographic measurement of LUS thickness using trans-vaginal ultrasound (p value= 0.001).The scar thickness in the third trimester (36-40 week) had a significant relation with the mode of delivery. 2.4 mm was considered the critical cutoff value of the LUS thickness above which safe vaginal delivery can be achieved. This critical cutoff value was derived from the ROC curve with sensitivity, specificity, PPV, and NPV 75.0%, 85.7%, 27.3%, and 98.0%, respectively. Conclusion: Measurement of the lower uterine segment thickness by TVS seems to be a good screening test with its obviously high sensitivity and negative predictive value. LUS thickness of