A 3-week-old-girl in the neonatal intensive care unit develops abdominal distension, vomiting, and blood-streaked stools. She had previously tolerated formula feeds and had normal stool and urine output. She was born at 27 weeks gestation to an 18-year-old-mother. The pregnancy was complicated by premature rupture of membranes and preterm delivery. Abdominal x-ray shows thin curvilinear areas of lucency that parallel the bowel wall lumen. Which of the following is the most likely diagnosis?

Question

A 3-week-old-girl in the neonatal intensive care unit develops abdominal distension, vomiting, and blood-streaked stools.  She had previously tolerated formula feeds and had normal stool and urine output.  She was born at 27 weeks gestation to an 18-year-old-mother.  The pregnancy was complicated by premature rupture of membranes and preterm delivery.  Abdominal x-ray shows thin curvilinear areas of lucency that parallel the bowel wall lumen.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec160b_3956_e4ae_9249_79dcedba0871_MD0001_00 This infant has pneumatosis intestinalis (ie, air in the bowel wall), which can be seen on abdominal x-ray as thin curvilinear areas of lucency (red arrows) that parallel the lumen. In an infant with abdominal distension and bloody stools, this finding is diagnostic for necrotizing enterocolitis (NEC). NEC is one of the most frequent gastrointestinal emergencies affecting newborns. It occurs predominantly in preterm infants secondary to gastrointestinal and immunologic immaturity. Upon initiation of enteral feeding, bacteria are introduced into the bowel where they proliferate excessively due to compromised immune clearance. Impaired mucosal barrier function allows the bacteria to invade the bowel wall, causing inflammation and ischemic necrosis of the terminal ileum and colon. As the disease progresses, the bowel becomes congested and gangrenous with the formation of intramural gas collections. Up to 30% of affected neonates die, especially when disease is complicated by intestinal perforation. Survivors are at risk for strictures and bowel obstruction secondary to fibrosis that occurs as the inflammation subsides. (Choice A) Duodenal atresia classically presents with the double bubble sign of air in the stomach and proximal duodenal pouch. Affected infants generally have bilious emesis shortly after birth. (Choice B) Hirschsprung disease manifests with failure to pass meconium in the first 48 hours after birth. On x-ray, the large intestine appears dilated proximal to the aganglionic portion of bowel; contrast enema will show a narrow-caliber transition zone. (Choice C) Malrotation of the bowel occurs when the midgut does not rotate normally during the first trimester, leaving the small and large bowel malpositioned. Malrotated bowel is at high risk of obstruction and ischemia due to twisting around its blood supply (volvulus). However, the finding of pneumatosis intestinalis is more specific for necrotizing enterocolitis. (Choice E) Pyloric stenosis is caused by hypertrophy of the pyloric sphincter and leads to gastric outlet obstruction. It presents with nonbilious vomiting after feeding and a palpable ball of muscle ("olive") in the abdomen. Pyloric stenosis is not associated with bloody stools or pneumatosis intestinalis. Educational objective: Necrotizing enterocolitis is one of the most common gastrointestinal emergencies affecting newborns. It is characterized by bacterial invasion and ischemic necrosis of the bowel wall, and is associated with prematurity and initiation of enteral feeding. Abdominal x-ray showing pneumatosis intestinalis (ie, air in the bowel wall) confirms the diagnosis. __________ References: A clinical perspective of necrotizing enterocolitis: past, present, and future. (http://www.ncbi.nlm.nih.gov/pubmed/23415262) Necrotizing enterocolitis: review of state-of-the-art imaging findings with pathologic correlation. (http://www.ncbi.nlm.nih.gov/pubmed/17374854)

A 3-Week-Old-Girl in the Neonatal Intensive Care Unit Develops Abdominal