Neonatal gastrointestinal masses arising late in gestation.

Gastrointestinal masses arising late in gestation form a small but important subgroup of neonatal abdominal masses. Thirteen infants were seen in the first day of life with abdominal distension or a mass. They had radiographic evidence of a mass and intestinal obstruction, and had masses containing meconium, liquid, or necrotic bowel in association with peritonitis. Results indicated a varied etiology. Six cases seemed to belong to one of three previously described entities: volvulus with pseudocyst formation, cystic meconium peritonitis, or segmental dilatation of the bowel. The other seven had features common to two or more of these entities.