Sonographic predictors of postnatal bowel atresia in fetal gastroschisis

Abstract

Objective To estimate the association between antenatal bowel dilation and postnatal small bowel atresia in fetal gastroschisis and to establish a threshold at which the risk of adverse neonatal outcome increases. Methods 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 diagnoses and outcomes, from the last ultrasound exam before delivery. Fetal intra- and extra-abdominal bowel dilation as well as bowel wall thickness was measured. Previously published definitions of bowel dilation including >6mm, >10mm, >14mm and >18mm were evaluated for association with the primary outcome of bowel atresia. The optimal threshold to define fetal bowel dilation was determined by evaluating the significance of association as well as test performance characteristics. Results Of 109 consecutive patients with fetal gastroschisis, there were 4 cases of intrauterine fetal demise and 3 neonatal deaths. Of the 94 live births with complete outcome data, 39 (41.5%) had measurable intra-abdominal bowel dilation (IABD). There were 14 (14.9%) cases of bowel atresia. Using a threshold of >14mm, IABD was significantly associated with an increased risk for bowel atresia (RR 3.1, 95% CI 1.2-8.2) with a sensitivity of 57.1%, specificity of 75.0%, positive predictive value of 28.6% and negative predictive value of 90.9%. IABD >14mm was also associated with a significantly longer neonatal intensive care unit length of stay. There was no significant association between extra-abdominal bowel dilation and bowel atresia at any of the thresholds evaluated. Conclusion IABD >14mm is associated with an increased risk for postnatal bowel atresia in fetal gastroschisis. This finding may be useful in counseling patients regarding the anticipated postnatal course for their neonate.

Prenatal Risk Factors and Outcomes in Gastroschisis: A Meta-Analysis

“…Three studies 24,34,41 explored the association between IABD and the overall postnatal LOS. These studies used different thresholds of dilatation to define the bowel as abnormal; in the largest study, 24 fetuses with an IABD .14 mm had a significant prolonged LOS compared with those with less dilated bowel (80.…”

“…These studies used different thresholds of dilatation to define the bowel as abnormal; in the largest study, 24 fetuses with an IABD .14 mm had a significant prolonged LOS compared with those with less dilated bowel (80. 34 could not find any association between IABD and length of hospitalization (Table 5).…”

“…Two studies 24,34 explored the association between IABD and the TFEF. Both did not report any significant increased risk in fetuses showing IABD regarding this outcome (Table 6).…”

“…Only 1 study 24 explored the association between BWT and LOS. In this study, fetuses with a BWT .3 mm had significantly longer stay in the hospital (100.5 median days, IQR 82.0-196.0) compared with those without (48.5 median days, IQR, 31.0-81.5) ( Table 5).…”

“…Looking at selected papers (Table 5 and 6) and assuming that IABD was a prenatal sign of complex gastroschisis, we showed that in the 3 largest series, there was a significant association between IABD/EABD and longer LOS. 24,33,41 In a recent systematic review, our group explored the role of prenatal ultrasound in detecting non-duodenal small bowel atresia in otherwise normal fetuses. 47 We found that ultrasound had a poor accuracy in detecting small bowel atresia either using bowel dilatation or polyhydramnios.…”