The natural history of meconium peritonitis diagnosed in utero.

The authors reviewed their experience with meconium peritonitis (MP) diagnosed in utero to define criteria for prenatal and postnatal management. Prenatal diagnosis was made by identifying abdominal calcification on serial ultrasound examinations in nine fetuses, between 18 and 37 weeks' gestation. Cases without associated bowel abnormalities were considered "simple MP" and those with bowel abnormalities were considered "complex MP." Five cases of simple MP were identified at 18, 23, 30, 34, and 37 weeks' gestation. These five fetuses were delivered at term and had normal abdominal examinations. Abdominal radiographs were obtained in three showing normal bowel gas patterns, and abdominal calcifications in only two. All five patients were fed uneventfully. Four cases of complex MP were identified at 26, 26, 31, and 31 weeks' gestation. All four fetuses had dilated loops of bowel. Two of the four had meconium cysts, one of which was associated with ascites and the other with polyhydramnios. Shortly after birth both infants with meconium cysts required ileal resection and ileostomy for ileal atresia and ileal perforation, respectively. The remaining two infants had no evidence of dilated bowel, meconium cyst, or ascites on postnatal radiograph and were fed uneventfully. These data suggest that only 22% of fetuses with a prenatal diagnosis of MP develop complications that require postnatal operation. Gestational age at diagnosis does not correlate with postnatal outcome. Fetuses with complex MP are at increased risk for postnatal bowel obstruction and perforation.