Impact of Cesarean Delivery Patterns and Scar Thickness on Subsequent Pregnancy Outcomes: A Community-Based Study in Southern Iraq

Background: The integrity of the lower uterine segment scar following cesarean section (CS) is a critical determinant of safety in subsequent pregnancies. Sonographic measurement of the uterine scar niche and residual myometrial thickness provides a non-invasive means of stratifying risk for uterine rupture, scar dehiscence, and adverse perinatal outcomes. Despite a nationally elevated CS rate in Iraq, data from local populations remain scarce. Objective: To evaluate the relationship between lower uterine segment (LUS) scar thickness measured by transabdominal ultrasonography at 36–38 weeks of gestation and subsequent obstetric outcomes in women with a previous cesarean section attending Babylon Educational Hospital for Gynecology and Pediatrics, Iraq. Methods: A prospective cohort study was conducted between January 2023 and December 2024. A total of 215 pregnant women with one or more prior CS were enrolled and classified by LUS thickness: Group I (thin scar, <2.5 mm), Group II (adequate scar, 2.5–3.5 mm), and Group III (thick scar, >3.5 mm). Maternal and neonatal outcomes including mode of delivery, intraoperative uterine rupture or dehiscence, blood transfusion, neonatal Apgar scores, NICU admission, and birth weight were recorded and analyzed. Results: Of the 215 participants, 67 (31.2%) had a thin scar, 89 (41.4%) an adequate scar, and 59 (27.4%) a thick scar. Complete uterine rupture occurred exclusively in Group I (7.5%), and scar dehiscence was significantly more frequent in Group I (20.9%) compared with Groups II (2.2%) and III (0%) (p<0.001). Emergency CS, blood transfusion, and neonatal NICU admission were all significantly higher in Group I. Logistic regression identified LUS thickness as an independent predictor of uterine dehiscence (OR 0.34 per mm increase; 95% CI 0.18–0.63; p=0.001). Conclusion: Lower uterine segment scar thickness measured at 36–38 weeks of gestation is a reliable sonographic predictor of uterine scar complications and adverse perinatal outcomes in Iraqi women. Routine third-trimester LUS assessment should be incorporated into antenatal care protocols for women with previous cesarean delivery.