131: Spontaneous Intestinal Perforation

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.

Five percent in extremely low birthweight infants.

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.

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.

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.

SIP is suspected when low birthweight infants present with the symptoms and signs described in Section V.

1. 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:

   1. Early presentation usually in the first week of life

   2. Physical findings of abdominal distension and bluish discoloration of abdominal wall, occasionally extending to the groin and to the scrotum in male infants

   3. Free air with absence of pneumatosis or portal venous gas on abdominal radiograph

2. Laboratory studies

   1. Complete blood count (CBC) with differential. May have elevated or low white blood cell count. May also have low platelet count. Elevated percentage of bands may be present.

   2. Disseminated intravascular coagulation (DIC) panel. Prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen degradation products, and fibrinogen level need to be corrected if abnormal and infant needs surgical intervention.

   3. Blood culture. Candida and Staphylococcus epidermidis have been associated with SIP. These organisms colonize the gastrointestinal tract of unfed or minimally fed infants and may be released after the bowel perforation.

   4. Electrolyte panel.

   5. Blood gas. May have respiratory and/or metabolic acidosis.

3. Imaging and other studies

   1. Flat plate radiograph of the abdomen. There may be a gasless abdomen or ileus. Free air may be seen.

   2. Lateral decubitus and cross-table lateral studies of the abdomen. Presence of free air is indicative of intestinal perforation

1. Medical management

   1. NPO to allow gastrointestinal rest for 7–14 days. Total parenteral nutrition to provide basic nutritional needs.

   2. Gastric decompression with large-bore orogastric tube (Replogle) at low intermittent or continuous suctioning.

   3. Close monitoring of vital signs and abdominal circumference.

   4. Respiratory support. Provide optimal respiratory support to maintain acceptable blood gas parameters.

   5. Circulatory support. There may be third spacing of fluid, which requires effective volume replacement. Ionotropic support may be needed to maintain normal blood pressure.

   6. Strict fluid intake and output monitoring. Try to maintain urine output of 1–3 cc/kg/h. Provide fluid replacement to correct third-space losses.

   7. Antibiotic therapy. Treat with parenteral antibiotics for 7–10 days. Antibiotic regimen to cover pathogens including S. epidermidis and Candida, along with effective gram-positive, gram-negative, and anaerobic coverage. See doses in Chapter 148. Recommendations are to start fluconazole and one of the following antibiotic regimens:

      1. Vancomycin, gentamicin, and clindamycin (or metronidazole)

      2. Vancomycin and Zosyn (piperacillin/tazobactam)

      3. Vancomycin, gentamicin, and Zosyn

2. Surgical management. The optimal surgical management continues to be controversial. The prospective randomized trials by Moss et al and Rees et al included infants with SIP, and both studies showed similar clinical outcomes using the 2 surgical techniques. The concern, expressed more in the latter study, was the high number of infants requiring secondary laparotomies for failure of clinical improvement or latter development of bowel obstruction. Peritoneal drain is an attractive option for very unstable low birthweight infants since it can be done with relative ease at the bedside using local anesthesia. In one retrospective study, infants with elevated percent band count and hypotension requiring vasopressor support were at higher risk for secondary laparotomy, and this subset may thus benefit from primary laparotomy.

   1. Laparotomy with primary repair. An abdominal incision is made and the bowel is explored. The segment of the bowel with perforation is resected and followed by end-to-end anastomosis of the bowel loops, or creation of an ileostomy and distal mucous fistula. Reanastomosis is usually undertaken after 8–12 weeks.

   2. Peritoneal drain placement. After making a small transverse incision in the abdomen, a Penrose drain is placed. The drain is removed when there is no meconium or intestinal drainage. After return of bowel function, feeds are started or a contrast enema is done to ensure patency of the distal ileum and colon.

   3. Laparoscopy with mini-laparotomy. This is a procedure recently described in which a diagnostic laparoscopy is done at the bedside. The diagnosis is confirmed and the site of perforation is localized. The affected bowel loop is then either exteriorized or primarily repaired.

Lower morbidity and mortality as well as neurodevelopmental impairment, as compared to intestinal perforation following necrotizing enterocolitis. Long-term survival of infants with SIP is 64–90% with improved medical and surgical care in the NICU. However, infants who develop SIP do have higher risk for periventricular leukomalacia and retinopathy of prematurity when compared with infants of similar gestational age without SIP.

Caution regarding early use of indocin (within first week of life), especially in infants who may be stressed with endogenously elevated cortisol levels. Avoid combined use of indocin and hydrocortisone in preterm infants. Close monitoring of extremely low birthweight infants for any signs of SIP.