Predi̇cti̇ve value of sonographi̇c measurement of lower uteri̇n segment

Objective: Cesarean section rates are increasing day by day around the world. For many women who have had a previous cesarean delivery, Vaginal birth after cesarean (VBAC) is a viable procedure. In this particular study, we examined the predictive value of sonographic uterine lower segment measurements in successful VBAC. Methods: The data of pregnant women who were followed up for VBAC between 2019 and 2021 in Bezmialem Vakıf University Medical Faculty Hospital, Department of Obstetrics and Gynecology, were retrospectively analyzed. Pregnant women aged 18-45 years, who had a previous cesarean section at 32 weeks or more, with vertex presentation, estimated fetal weight below 4250 g, and no fetal anomaly detected in antenatal follow-ups were included in the study. In all patients, lower segment total thickness, residual myometrial thickness and cervical canal length were measured by transvaginal ultrasonography at 36-39 weeks. Basic dermographic, obstetric, clinical and sonographic data, maternal and neonatal outcomes of the patients were recorded. Results: VBAC was successful in 45 (69,2%) of the 65 patients included in the study, and other 20 (30,8%) delivered cesarean section. The two groups were similar in terms of basic demographic data (p>0.05). Induction of labor was applied to 10 (22,2%) patients in the successful VBAC group and 17 (85%) patients in the unsuccessful group, and a statistically significant difference was found (p<0.001).When the BISHOP scores during hospitalization were evaluated, it was found to be significantly higher in the successful VBAC group [5(1-11) vs 2(1-11) p<0.001]. While cervical length was significantly shorter in the successful VBAC group, there was no difference between the two groups in total lower segment thickness and residual myometrial thickness [respectively (37.48±9.08 vs 41.4±6, p=0.047), (4.49±6) 1.33 vs 4.72±1.97,p>0.05), (2.04±0.8 vs 2.07±0.92, p>0.05)]. Uterine and bladder rupture took place during VBAC for 1 case only in our study; lower segment thickness of the case was 2,3 and residual myometrial thickness was 1,1. Logistic regression analysis revealed that labor induction was the only factor that significantly reduced the success of VBAC (p=0.036). Conclusion: Lower segment measurements have no value in predicting VBAC success. The most important factor predicting the success of VBAC is the spontaneous onset of labor. Keywords: Vaginal Delivery After Cesarean Section, Cesarean Section, Total Lower Segment Thickness, Ultrasonography, Uterine Rupture