Bowel abnormalities in the fetus--correlation of prenatal ultrasonographic findings with outcome.

OBJECTIVE: Our purpose was to correlate ultrasonographic findings with postnatal outcome in cases of fetal bowel pathologic disorders detected by either prenatal evaluation or diagnosed in the neonatal period. STUDY
DESIGN: A total of 16,471 consecutive fetuses were scanned in the midtrimester or later. Fetuses were included in the study group if the prenatal ultrasonographic evaluation suggested gastrointestinal pathologic features or if gastrointestinal pathologic features were identified by postnatal evaluation. Prenatal ultrasonographic findings and postnatal outcome were collected by chart review. Prenatal ultrasonographic findings were compared with outcome. Results were compared by Fisher's exact test. Sensitivity and positive predictive values were determined.
RESULTS: Of the 16,471 fetuses scanned, 15,090 (91.6%) had complete postnatal follow-up. Eighty-nine fetuses had a bowel lesion suspected by prenatal ultrasonography. Twenty-two had dilated bowel distal to the duodenum, 33 had isolated hyperechoic bowel, 20 had ascites, and 14 had a cystic abdominal mass. Twenty-two fetuses (22/89 or 25%) were found at neonatal evaluation to have a gastrointestinal lesion. In those fetuses with small-bowel lesions, the sensitivity of ultrasonography was 100% and the positive predictive value was 72.7%. For large-bowel lesions the sensitivity of ultrasonography was only 7.7%, and the positive predictive value was 18%. No ultrasonographic parameter could unequivocally differentiate between the normal and abnormal outcome groups, but progressive bowel dilatation in the third trimester and hyperperistalsis with a dilated bowel loop were frequently found in the cases of small bowel obstruction. Four of the cases of dilated bowel (18.2%) were related to cystic fibrosis.
CONCLUSION: Bowel abnormalities in the fetus are manifest in diverse ultrasonographic findings, making accurate prediction of lesions difficult. The sensitivity of prenatal ultrasonography to detect large-bowel lesions was poor, although it was 100% sensitive in the detection of small-bowel lesions. Cystic fibrosis should be considered in all fetuses with bowel abnormalities suspected on prenatal ultrasonography.