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A spontaneous intestinal perforation (SIP) is a single intestinal perforation typically involving the antimesenteric border of distal ileum, which usually occurs without a defined prodrome in extremely premature infants in the first 1–2 weeks of life. These infants usually have not been fed (or have received minimum feeds). At the area of perforation, 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.
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Five percent in extremely low birthweight infants.
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Prematurity, maternal chorioamnionitis, outborn status (requiring transport to the neonatal intensive care unit [NICU]), and male gender have been linked with occurrence of SIP. Early administration of glucocorticoids (both dexamethasone and hydrocortisone) has been associated with development of SIP. Similarly, early use of indomethacin (first 3 days) has been associated with SIP. 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.
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SIP histopathology is associated with robust mucosa, with or without submucosal hemorrhage, and segmental/focal necrosis or absence of muscularis externa. These findings are not consistent with an ischemic insult. While 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: Steroids promote mucosal growth at the expense of bowel wall integrity with thinning of the submucosal layer. 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' age leads to increased intraluminal pressure in the bowel leading to bowel perforation.
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These infants usually present at about 7–10 days of life (range of 0–15 days). They have not been fed or are receiving minimal feeds and present with sudden deterioration with abdominal distension, bluish discoloration over abdomen, hypotension, and metabolic acidosis.
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SIP is suspected when low birthweight infants present with the symptoms and signs described in Section V.
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Clinical diagnosis. This is based on sudden presentation with abdominal distension and bluish discoloration of abdominal wall, often associated with hypotension and clinical deterioration. Three features are helpful in distinguishing SIP from NEC with perforation:
Early presentation usually in the first week of life
Physical findings of abdominal distension and bluish discoloration of abdominal wall, occasionally extending to the groin and to the scrotum in male infants
Free air with absence of pneumatosis or portal venous gas...