494: Antenatal intra-abdominal bowel dilation in the prediction of postnatal bowel atresia in fetuses with gastroschisis

Abstract

Given the dramatic difference in postnatal hospital course in the setting of bowel atresia with gastroschisis, we aimed to estimate the association between antenatal intra-abdominal bowel dilation (IABD) and postnatal small bowel atresia in gastroschisis and to evaluate its predictive ability. A retrospective cohort study of singleton gestations with an antenatal diagnosis of gastroschisis seen in our ultrasound unit from 2001-2010. Stored images were reviewed, blind to postnatal outcomes, from the last ultrasound exam before delivery, and the transverse diameter of the largest dilated loop of intra-abdominal small bowel measured. Previously published definitions of IABD including >6mm, >10mm, and >14mm were evaluated for association with the primary outcome of bowel atresia. Secondary outcomes included neonatal intensive care unit (NICU) length of stay, necrotizing enterocolitis (NEC), time to complete closure, time on total parenteral nutrition (TPN), and time to initial and full enteral feeding. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUC) were calculated. Of 94 consecutive live births with gastroschisis, 39 (41.5%) had IABD at their last ultrasound. The range of IABD was 7mm-75mm. There were 14 (14.9%) cases of bowel atresia. There was no significant association between IABD and bowel atresia when thresholds of >6mm and >10mm were used to define IABD; however, there was a significantly increased risk of bowel atresia with IABD>14mm (28.6% v. 9.1%, RR 3.1, 95% CI 1.2-8.2). Sensitivity, specificity, PPV, and NPV for IABD>14mm and bowel atresia were 57.1%, 75.0%, 28.6%, and 90.9%, respectively. The AUC for IABD and bowel atresia was 0.73 (95% CI 0.57-0.89). IABD>14mm is associated with an increased risk for bowel atresia; however, the PPV remains low due to the rarity of the finding. Given the high NPV, patients can be counseled that in the absence of this finding, the risk of postnatal bowel atresia is low for their neonate with gastroschisis. Tabled 1