Association Between Obstetric Conjugate Diameter Measured by Transabdominal Ultrasonography During Pregnancy and the Type of Delivery

Background: normal morphological features of the maternal pelvis are an important prerequisite to vaginal delivery. objectives: we aimed to evaluate the association between obstetric conjugate diameter (ocd) measured by ultrasonography and the type of delivery, vaginally (v) or by cesarean (c) section. patients and methods: pelvimetry was performed in 200 primigravid women for fetal cephalic presentation. the ocd was measured twice by transabdominal ultrasonography during 25-30 weeks and 30-35 weeks of pregnancy. results: the mean ocd of both sonographies in groups v and c was 125.51± 8.35 mm (105-144.5) and 112.99 ± 8.53 mm (96-134.5), respectively, which was significantly lower in group c (p < 0.001). the values of ocd between the first and second measurements were not different significantly (p=0.065). c-section was indicated in 65 (32.5%) mothers. the optimal cut-off point for the ocd in the prediction of vaginal delivery was ≥ 119.75 mm, with a sensitivity and specificity of 80% and 78.5%, respectively. conclusion: the us measurement of ocd might be an accurate method that almost always remains constant during late pregnancy; it is easy to measure and might be confidentially employed for predicting c-section, but needs more precise studies to be used widely.