Paediatric ImagingNecrotizing enterocolitis
a complication of low
perfusion of the gastrointestinal tract, most frequently seen in low birthweight infants, but also occurring in more mature infants. There is mucosal injury secondary to intestinal ischaemia. Known risk factors apart from prematurity include surgery or instrumentation such as catheterization during the neonatal period. The baby presents with lethargy, refusal of feeds and the development of
abdominal distension, followed by vomiting, usually bile stained, and rectal bleeding in about 25% of cases. Radiologically, pneumatosis intestinalis typically is seen (
Fig.1), mainly in the colon, although necrotizing enterocolitis can affect any part of the gastrointestinal tract. Other features include thickening of the bowel wall with separation of bowel loops, a fixed distended loop of bowel and ascites easier to detect on
ultrasound.
Adynamic ileus is common.
Other immediate abdominal complications of necrotizing enterocolitis include fistula and intraperitoneal abscess formation (Fig.2). Sepsis may be systemic and cause osteomyelitis or septic arthritis which may be masked by the antibiotic treatment.
Air may be visible in the portal venous system (see gas, portal vein (VII), Fig. 1) seen as a typical branching pattern within the liver. Lesser amounts of portal vein gas may be seen on ultrasound examination as bubbles within the portal venous system.
Perforation is a recognised complication. If there is a large amount of free air this is seen as a radiolucent shadow over the abdominal cavity, and there is often demonstration of the ligamentum falciparum, and air on both sides of the bowel wall (see falciform ligament (VII), Fig. 1). Small amounts of free gas are best appreciated on a decubitus film of the abdomen. Loculated collections of air, e.g. in the subhepatic region, are also frequent.
Medium-term complications include stricture formation within the intestine, usually in the colon, clinically presenting with recurrent abdominal distension on attempts to reintroduce feeding. Contrast studies of the gastrointestinal. tract are required to demonstrate this.
Long term complications include a short bowel syndrome, if there has been extensive resection, adhesive obstruction, and the effects of musculoskeletal sepsis.
HC
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Film 2 weeks later. The intramural gas has resolved. There is a bubble of gas in the left flank outside the bowel, distension of the flanks, central dilated featureless bowel and swelling of the left abdominal wall extending to the axilla, all secondary to perforation of necrotizing enterocolitis and abscess formation.
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Necrotizing enterocolitis, Fig.1 | | Necrotizing enterocolitis, Fig.2 | |