TWENTY-FIRST ANNUAL GENERAL & SCIENTIFIC MEETING

Abstract

Introduction The rate of caesarean deliveries (CD) has increased globally in recent years. CD accounts for more than 1 in 5 births; this is predicted to rise to about a third by 2030. When indicated, CD preserves the lives of mother and baby; however, it has associated complications. Vaginal birth after CD (VBAC) has gained traction in recent years because of its high success rate, but identifying which women are likely to have a successful VBAC remains challenging. Methods Myometrial lower uterine segment thickness (mLUS) and full lower uterine segment thickness (fLUS) were measured with transvaginal ultrasound (TVUS). The women were managed according to local protocols with the clinicians blinded to the ultrasound measurements. The LUS was measured intraoperatively for comparison with ultrasound measurements. Results 311 pregnant women with one previous CD were enrolled; 147 underwent elective CD and 164 underwent a TOLAC. 96(58.5%) women had a successful vaginal birth. The mLUS was comparable to the intraoperative measurement in the elective CD group with LUS thickness <5mm(bias of 0.01, 95% CI-0.10 to 0.12mm); fLUS overestimated LUS<5mm( bias of 0.93, 95% CI 0.80-1.06mm). Successful vaginal birth rate correlated with higher mLUS values (OR 1.30, 95% CI 1.03 1.64). LUS measurement ≤2.0 mm was associated with an increased risk of uterine defects with a sensitivity of 91.7% (95% CI 61.5–99.8%) and specificity of 81.8% (95% CI75.8–86.8%). Discussion Our findings revealed that mLUS values compared favourably with intraoperative measurements. The rate of successful VBAC increased with increasing mLUS measurements with a 71/105 (67.6%) success in mLUS ≥3.0 mm, 25/48 (52.1%) success in measurements between 2.1 and 2.9 mm and no successful VBAC with mLUS ≤2 mm (0/11). Conclusion Accurate TVUS measurement of the LUS is feasible in a resource-limited setting. This could help in making safer decisions on mode of birth in limited-resource settings.