Gastroschisis: can sonography of the fetal bowel accurately predict postnatal outcome?

To determine whether prenatal sonographic features of the small bowel can accurately predict postnatal outcome in fetuses with gastroschisis, the sonograms of 24 fetuses with prenatally detected gastroschisis were retrospectively reviewed for fetal bowel features including small bowel dilatation and bowel wall thickening. To identify a relationship between the sonographic features and neonatal outcome, each feature was analyzed against eight adverse clinical outcome measures including bowel obstruction or atresia, necrosis, and need for bowel resection, using chi-square analysis and Kendall's taub correlation. When a relationship was identified, the sensitivity and specificity of the sonographic feature for predicting adverse outcome were determined. Only maximum small bowel diameter was related to postnatal bowel complications. Significantly more fetuses with a maximum small bowel diameter of greater than 11 mm (7/12) had bowel complications than did fetuses with MBD 11 mm or less (2/12) P < 0.05). Using a cutoff point of greater than 11 mm for maximum small bowel diameter, the sensitivity was 78%, specificity 66%, and positive predictive value 71% for predicting postnatal bowel complications. However, in only seven of 24 cases did the two observers make the same maximum small bowel diameter measurement, and in 14 of 24 cases their measurements differed by 2 mm or more. The observers varied sufficiently in their measurements to shift three fetuses (13%) between categories (< or = 11 mm or > 11 mm). Although a maximum small bowel diameter of 11 mm stratified our fetuses, this measurement may not be clinically meaningful.