Chapter 46

### Key Points

1. Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of the newborn, primarily affecting preterm infants and those with cyanotic heart disease. Up to 50% of infants who develop NEC will require surgical intervention.

2. Major risk factors for NEC include prematurity, hypoxia, bacterial infection, congenital heart disease, and initiation of enteral nutrition.

3. Infants with NEC may present with feeding intolerance, bloody stools, respiratory distress, or hypoperfusion. Clinical and radiographic criteria are summarized in the Bell grading system.

4. In an infant with suspected NEC, initial laboratory studies should include a complete blood cell count, electrolyte panel, a blood gas to determine the acid–base status of the patient, and blood cultures.

5. Infants with suspected or confirmed NEC should be treated with bowel rest, broad-spectrum antibiotics, and volume resuscitation.

6. The only absolute indication for surgical intervention is the presence of the pneumoperitoneum. Relative indications for surgery include a fixed intestinal loop on serial plain abdominal radiographs, portal venous gas on plain abdominal radiograph, abominal wall erythema, a palpable abdominal mass, a positive paracentesis, and clinical deterioration despite maximal medical therapy.

7. Based on accumulated evidence, we recommend initial peritoneal drainage (PD) only for VLBW infants who are hemodynamically unstable with respiratory embarrassment secondary to abdominal distention; however, subsequent laparotomy is warranted.

8. Definitive primary laparotomy with resection of necrotic intestine is best suited for infants weighing >1500 g or VLBW neonates who can tolerate the initial operation.

9. The standard of care for focal NEC is resection with creation of a proximal enterostomy, with or without a distal mucous fistula. Primary anastomosis may be considered in a hemodynamically stable infant with minimal peritoneal soilage.

10. Options for treatment of multifocal disease are varied, but the principal goal is resection of the obviously necrotic intestine with preservation of intestinal length to avoid short bowel syndrome.

11. Long-term complications of NEC include stricture, short bowel syndrome, and neurodevelopmental impairment.

### Introduction

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in the newborn. The majority of the cases occur in infants born at fewer than 36 weeks gestational age. In fact, approximately 1% to 5% of all preterm infants develop NEC. However, NEC has also been reported in term infants, particularly those with cyanotic heart disease. As a result of recent advances in the care of preterm infants, the incidence of NEC has been rising. In its most severe form, NEC is characterized by full-thickness destruction of the intestinal wall, which may lead to intestinal perforation, subsequent peritonitis, sepsis, and death. Up to 50% of infants who develop NEC will require surgical intervention. The mortality rate ranges from 10% to 50% but approaches 100% in infants with panintestinal involvement. Infants who survive may experience future morbidity such as intestinal obstruction secondary to stricture formation or adhesions, or they may develop intestinal failure characterized by intestinal dysmotility and long-term dependency on parenteral nutrition.

### Pathogenesis

Multiple risk factors have been ...

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