Inguinal hernias develop most often in male neonates, particularly if they are premature (in which case the incidence is about 10%). The right side is affected most commonly, and about 10% of inguinal hernias are bilateral. Because inguinal hernias can become incarcerated, repair should be done shortly after diagnosis. For premature infants, repair typically is not done until they have reached a weight of 2 kg. In contrast, umbilical hernias rarely become incarcerated, close spontaneously after several years, and do not ordinarily need surgical repair.

In neonates, gastric perforations are often spontaneous and typically occur in the first week of life. Although this is overall an uncommon occurrence, perforation is more common among premature than full-term infants. The etiology of gastric perforation is uncertain, but the perforation may be due to a congenital defect in the stomach wall, usually along the greater curvature. The abdomen suddenly becomes distended, infants develop respiratory distress, and massive pneumoperitoneum is seen on abdominal x-ray. This disorder has a high mortality rate (25%), which is even greater in premature infants (60%). Prognosis is usually good after surgical repair of the perforation.

Ileal perforation is another uncommon disorder that is most common among very low-birth-weight infants (< 1500 g) and during the first 2 wk of life. It has been associated with chorioamnionitis, postnatal glucocorticoid use, and indomethacin therapy to close a patent ductus arteriosis. The etiology of ileal perforation is uncertain but may be related to a muscular defect in the ileal wall or to a problem with nitric oxide synthase and local ischemia resulting from vasoconstriction. Treatment of ileal perforation is stabilization with IV fluids and antibiotics, followed by surgical repair.

Mural thrombi or emboli may occlude a mesenteric artery after high placement of an umbilical artery catheter. Such an occurrence is extremely rare but can cause extensive intestinal infarction requiring surgery and intestinal resection.