Superior mesenteric artery Doppler velocimetry and ultrasonographic assessment of fetal bowel in gastroschisis: a prospective longitudinal study.

OBJECTIVE: Our purpose was to determine whether Doppler velocimetry of the superior mesenteric artery and its mesenteric branches and ultrasonographic assessment of bowel can predict postnatal outcome in fetuses with gastroschisis.

STUDY DESIGN: The normal reference range for the superior mesenteric artery pulsatility index was determined by studying 161 normal fetuses. Over a 24-month period superior mesenteric artery pulsatility index, superior mesenteric artery mesenteric branches systolic/diastolic ratio, bowel diameter, and bowel wall thickness were prospectively and longitudinally obtained from 17 fetuses with gastroschisis. Poor neonatal outcome was defined by bowel resection or staged repair of the defect or a hospital stay > 50 days.

RESULTS: Doppler velocimetry of the superior mesenteric artery and its mesenteric branches proved minimally useful in prognosticating neonatal outcome. No difference was found in the superior mesenteric artery pulsatility index between the good and poor neonatal outcome groups (p = 0.99). Longitudinal data analysis on all fetuses with gastroschisis showed an increase in bowel diameter with advancing gestation (p < 0.0001). A greater rate of increase in bowel diameter with advancing gestation was noted in the poor-neonatal-outcome group compared with the good-neonatal-outcome group (p < 0.01). Mean bowel diameter obtained before delivery was significantly greater in the poor-neonatal-outcome group (p = 0.03). Bowel diameter obtained at 28 to 32 weeks was the best predictor of poor neonatal outcome. A cutoff value of bowel diameter > 10 mm at 28 to 32 weeks had a sensitivity of 83%, a specificity of 88%, a positive predictive value of 83%, and a negative predictive value of 88% for poor neonatal outcome.

CONCLUSIONS: Doppler velocimetry of the superior mesenteric artery and its branches is not predictive of poor neonatal outcome in fetuses with gastroschisis. A bowel diameter > 10 mm between 28 and 32 weeks appears to be the best predictor of poor neonatal outcome. This newly defined variable warrants further investigation given its significant predictive power.