Prediction of Risk of Cesarean Delivery using Transvaginal Ultrasonography in Evaluation of Lower Uterine Segment Thickness of Singleton Pregnancy in Late third Trimester

Abstract

Background: The rising rates of cesarean delivery (CD) worldwide poses concerns regarding maternal and neonatal morbidity. Lower uterine segment (LUS) thickness has been studied as a predictor of uterine rupture during trial of labor in previous CD, but for predicting CD in women with spontaneous labor, the evidence remains inconclusive. Objective: This study aimed to evaluate LUS thickness measured via transvaginal ultrasound (TVS) during the late third trimester as a predictive factor for CD due to labor dystocia in singleton pregnancies. Method: In this prospective cohort study, 130 pregnant women with singleton pregnancies at 34-36+6 weeks of gestation were assessed using TVS at the antenatal care (ANC) unit of HRH Princess Maha Chakri Sirindhorn Medical Center, Thailand. LUS thickness was measured three times by using a protocol and the thinnest segment of the LUS thickness was recorded. The demographic and clinical data was recorded at enrollment. Delivery outcomes were analyzed, and the predictive accuracy of LUS thickness for CD was assessed using the area under the receiver operating characteristic (ROC) curve. Results: The mean LUS thickness for vaginal deliveries (VD) was 6.69 mm., while in CD was 7.01 mm., though this difference was not statistically significant (p value = 0.56). ROC yielded an AUC of 0.57 (95% CI: 0.45-0.70), indicating limited predictive value. Excluding non-reassuring fetal heart rate and fetal distress, the LUS thickness for cut-offs ≥ 6.5 mm. showed the moderate sensitivity (48.1%), specificity (41.5%), positive predictive value (PPV) of 19.1% and negative predictive value (NPV) of 73.6%. Conclusion: LUS thickness measurement alone has limited predictive capacity for CD due to labor dystocia in singleton pregnancies. The findings suggest that it should be combined with other clinical or ultrasound factor for increasing predictive accuracy for CD.