EFFECT OF PREVIOUS CAESARIAN SECTION ON 2ND TRIMESTER UTERINE ARTERY DOPPLER

Background: Previous cesarean section is increasingly common and has been implicated in altered uteroplacental vascular adaptation in subsequent pregnancies. Structural changes related to uterine scarring may influence uterine artery blood flow, particularly during the second trimester when placentation and vascular remodeling are critical. Abnormal uterine artery Doppler indices during this period have been associated with adverse maternal and fetal outcomes, including hypertensive disorders of pregnancy and fetal growth restriction. Understanding these vascular effects is important for improving antenatal surveillance and maternal–fetal risk assessment. Objective: To evaluate the effect of previous cesarean section on uterine artery Doppler resistive index during the second trimester of pregnancy. Methods: This comparative study included 100 pregnant women in the second trimester, divided equally into two groups: 50 with a history of previous cesarean section and 50 without prior cesarean section. Participants were recruited from tertiary ultrasound clinics in Lahore. Transabdominal ultrasound examinations were performed using high-resolution Doppler equipment. Gestational age was confirmed using fetal biometric parameters, and uterine artery Doppler assessment was carried out to measure the resistive index. Data were analyzed using appropriate statistical tests, with significance set at a p-value < 0.05. Results: The overall mean maternal age was 27.45 ± 4.61 years, and the mean gestational age at examination was 20.24 ± 2.32 weeks. Mean uterine artery resistive index was significantly higher in women with a previous cesarean section (0.710 ± 0.063) compared with those without a cesarean history (0.660 ± 0.058), with a mean difference of −0.05 (95% CI: −0.074 to −0.026; p = 0.0001). No statistically significant differences were observed between groups for maternal age, gestational age, or body mass index (p > 0.05). Conclusion: A history of previous cesarean section was associated with increased uterine artery resistive index during the second trimester, suggesting altered uteroplacental vascular resistance in subsequent pregnancies. These findings support the role of uterine artery Doppler as a useful tool for identifying vascular changes related to prior cesarean delivery and may aid in guiding closer antenatal monitoring.