Study of lateral placentation and its association with preeclampsia

Background: When the placenta is laterally located, it receives blood flow predominantly from one uterine artery, with minimal contribution from the contralateral artery via collateral circulation. Deficiency in this collateral circulation facilitates the development of preeclampsia (PE) and fetal growth restriction (FGR). Method: A prospective observational study was conducted in 180 primigravid women at 18-24 weeks and 32-36 weeks of gestation. Placental location was determined using ultrasonography (USG). General physical, systemic, and obstetrical examinations were performed, and patients were monitored prospectively for the development of preeclampsia, defined as new-onset hypertension after 20 weeks of gestation with proteinuria. Clinical manifestations were recorded, and pregnancy was terminated in cases of severe refractory hypertension. Results: Out of 180 patients, 108 (60.0%) had centrally located placentas and 72 (40.0%) had laterally located placentas. Mode of delivery in central placentation was 35 (19.4%) LSCS and 73 (40.5%) vaginal deliveries; in lateral placentation, 44 (24.4%) delivered via LSCS and 28 (15.5%) vaginally. Adverse obstetric outcomes were significantly higher in laterally located placentas: Intrauterine Growth Restriction (IUGR) in 11 (15.3%), Gestational Hypertension (GHTN) in 8 (11.1%), Preeclampsia in 23 (31.9%), PIH + IUGR in 5 (6.9%), PPROM in 2 (2.8%), and PPROM + IUGR in 2 (2.8%), compared to central placentation (IUGR 5.6%, GHTN 4.6%, Preeclampsia 3.7%, PIH + IUGR 1.9%). Sonographic detection of lateral placentation demonstrated a diagnostic sensitivity of 84.1%, specificity of 68.9%, positive predictive value (PPV) of 39.1%, and negative predictive value (NPV) of 94.3% for preeclampsia Conclusion: Laterally located placentation is a significant high-risk factor for preeclampsia and adverse fetal outcomes. Routine sonographic placental localization allows obstetricians to identify high-risk pregnancies early and implement preventive measures to reduce maternal and neonatal morbidity.