A spontaneous intestinal perforation (SIP) is a single intestinal perforation typically involving the antimesenteric border of distal ileum and usually occurs in extremely premature infants in the first 1 to 2 weeks of life. These infants, typically, have not been fed (or have received minimum feeds). If laparotomy is performed, a focal hemorrhagic necrosis with well-defined margins is observed, in contrast to ischemic and coagulative necrosis seen in necrotizing enterocolitis (NEC). The bowel proximal and distal to the perforation appears normal.
Two to three percent in very low birthweight (VLBW, birthweight <1500 g) infants and approximately 5% in extremely low birthweight (ELBW, birthweight <1000 g) infants.
Prematurity is the only well-established risk factor for SIP. Several antenatal and postnatal risk factors have been identified based on case series and datasets. These include placental chorioamnionitis, maternal antibiotics, male gender, inotropic agents, lack of initiation of feeding, severe intraventricular hemorrhage (IVH) (≥ grade 3), early administration of glucocorticoids (both dexamethasone and hydrocortisone), and early use of indomethacin to treat symptomatic patent ductus arteriosus. The risk is greater when there is combined exposure to indomethacin and either elevated endogenous cortisol levels or administration of exogenous glucocorticoids in the first 3 days of life.
SIP histopathology is characterized by preservation of the mucosal villus architecture and thinning of muscularis propria. Although some cases of SIP (especially in larger infants) can be associated with congenital deficits in the muscularis layer of the bowel, theories have been developed for the unique association of SIP with perinatal stress and postnatal early steroids and indomethacin exposure. The following sequence of events has been proposed: Early postnatal steroids promote mucosal growth at the expense of bowel wall integrity with thinning/necrosis of the submucosal layer (skewed trophism). Indomethacin, in combination with steroids, causes a transient ileus due to depletion of nitric oxide synthase. Swallowing of air and return of bowel motility at about 7 days of age leads to increased intraluminal pressure resulting in bowel perforation. Infection may have a role in the pathogenesis; Candida, Staphylococcus epidermidis, and cytomegalovirus have been isolated from peritoneal fluid and surgical intestinal specimens of infants with SIP.
These infants present suddenly with abdominal distension, bluish discoloration of the abdomen, hypotension, and metabolic acidosis. The bluish discoloration may extend into the groin and, in males, the scrotum. According to a large case series, 2 distinct groups have been described based on age of presentation: early SIP (0–3 days) and late SIP (7–10 days). Early SIP infants were larger (median birth weight of 1.4 kg) and less likely to have received antenatal glucocorticoids, indomethacin, surfactant, or mechanical ventilation compared with infants in the late SIP group (median birth weight of 775 g).