Enterocolitis, Necrotizing

Key Features

Essentials of Diagnosis

• Feeding intolerance with gastric residuals or vomiting

• Bloody stools

• Abdominal distention and tenderness

• Pneumatosis intestinalis on abdominal radiograph

General Considerations

• Most common in preterm infants, with an incidence of 10% in infants less than 1500 g

• In full-term infants, it occurs in association with polycythemia, congenital heart disease, and birth asphyxia

• Pathogenesis is multifactorial and includes

  • Ischemia

  • Immaturity

  • Microbial dysbiosis (proliferation of pathogenic bacteria with less colonization with beneficial or commensal bacteria)

  • Genetics

Clinical Findings

• Abdominal distention, tenderness

• Vomiting

• Increased gastric residuals

• Heme-positive stools

• Temperature instability

• Increased apnea and bradycardia

• Decreased urinary output

• Poor perfusion

Diagnosis

• Increased white blood cell count with an increased band count or, as the disease progresses, absolute neutropenia may be present

• Thrombocytopenia often occurs along with stress-induced hyperglycemia and metabolic acidosis

• Plain abdominal radiograph showing presence of pneumatosis intestinalis (air in the bowel wall) or biliary tract air confirms diagnosis

• Milder cases may exhibit only distention of bowel loops with bowel wall edema

Treatment

Medical

• Initial measures

  • Infant should take nothing by mouth

  • Nasogastric decompression of the gut

  • Maintenance of oxygenation

  • Mechanical ventilation if necessary

  • Intravenous fluids: enough to replace third-space gastrointestinal losses and restore good urinary output

• Other measures include

  • Broad-spectrum antibiotics (usually ampicillin, a third-generation cephalosporin or an aminoglycoside, and possibly additional anaerobic coverage)

  • Close monitoring of vital signs

  • Serial physical examinations and laboratory studies (blood gases, white blood cell count, platelet count, and radiographs)

Surgery

• Needed in < 25% of cases

• Indications

  • Evidence of perforation (free air present on a left lateral decubitus or cross-table lateral film)

  • Fixed dilated loop of bowel on serial radiographs

  • Abdominal wall cellulitis

  • Deterioration despite maximal medical support

Outcome

Follow-Up

• Total parenteral nutrition is provided until the disease is resolved (normal abdominal examination and resolution of pneumatosis), usually after 7–10 days

Prevention

• No proven strategies but use of trophic feedings, breast milk, and cautious advancement of feeds, as well as probiotic agents, may provide some protection

Prognosis

• Death occurs in 10% of cases

• Long-term prognosis is determined by the amount of intestine lost. Infants with short bowel require long-term support with intravenous nutrition

• Late strictures—about 3–6 weeks after initial diagnosis—occur in 8% of patients whether treated medically or surgically, and generally require operative management

• Infants with surgically managed NEC have an increased risk of poor neurodevelopmental outcome

References