A 3-week-old boy in the neonatal intensive care unit has several episodes of vomiting. The vomiting developed 6 hours ago and is bilious but nonbloody. The patient was born at 28 weeks gestation by vaginal delivery due to cervical insufficiency. Birth weight was 900 g (2 lb). The patient initially required mechanical ventilation but was extubated to oxygen via nasal cannula last week. He has advanced on continuous nasogastric formula feeds and has gained appropriate weight daily. The infant has had small, yellow, seedy stools but no bowel movement for the past 24 hours. Temperature is 35.6 C (96 F), blood pressure is 75/45 mm Hg, pulse is 165/min, and respirations are 70/min. Pulse oximetry is 97% on 2 L oxygen. Examination shows a lethargic neonate. The abdomen is tense and distended with hypoactive bowel sounds. Laboratory results indicate leukocytosis and metabolic acidosis. Which of the following imaging findings would most likely be seen in this patient?

Question

A 3-week-old boy in the neonatal intensive care unit has several episodes of vomiting.  The vomiting developed 6 hours ago and is bilious but nonbloody.  The patient was born at 28 weeks gestation by vaginal delivery due to cervical insufficiency.  Birth weight was 900 g (2 lb).  The patient initially required mechanical ventilation but was extubated to oxygen via nasal cannula last week.  He has advanced on continuous nasogastric formula feeds and has gained appropriate weight daily.  The infant has had small, yellow, seedy stools but no bowel movement for the past 24 hours.  Temperature is 35.6 C (96 F), blood pressure is 75/45 mm Hg, pulse is 165/min, and respirations are 70/min.  Pulse oximetry is 97% on 2 L oxygen.  Examination shows a lethargic neonate.  The abdomen is tense and distended with hypoactive bowel sounds.  Laboratory results indicate leukocytosis and metabolic acidosis.  Which of the following imaging findings would most likely be seen in this patient?

Quizplus · Accepted Answer

11ec25c8_d684_d89e_bc81_21ed8be4f4fe_MD0003_00 This infant has bilious emesis, abdominal distension, leukocytosis, and metabolic acidosis due to necrotizing enterocolitis (NEC). Pathogenesis of NEC involves inflammation and necrosis of intestinal mucosa with invasion of gas-producing bacteria. Premature and very low-birth-weight (<1.5 kg [3.3 lb]) infants are particularly vulnerable due to decreased bowel motility, increased intestinal permeability, and immature host defenses. Exposure to bacteria from enteral feeds, especially formula feeds, also increases the risk of NEC. Initial signs are often nonspecific (eg, lethargy, feeding intolerance), and neonates may be hypothermic (<36.5 C [97.7 F]) rather than febrile, as seen here. Bilious emesis and a tense, erythematous, distended abdomen are typical. Bloody stools are also a classic finding but may not be present in early stages. Leukocytosis and metabolic acidosis reflect inflammation and intestinal ischemia, respectively. The hallmark x-ray finding in NEC is air in the bowel wall, or pneumatosis intestinalis (red arrows). In addition, portal venous air (yellow arrows) is seen as branching areas of lucency over the liver due to gas-producing bacteria and the transmigration of gas from the bowel wall to the mesenteric and portal veins. Severe intestinal necrosis can also cause perforation and pneumoperitoneum. x-ray finding pneumoperitoneum Management of suspected NEC includes discontinuation of enteral feeds and administration of antibiotics; surgery may be required in severe cases. (Choice A) Pyloric stenosis presents with postprandial nonbilious emesis in an otherwise healthy 3- to 6-week-old infant. An olive-shaped abdominal mass may be palpable, and metabolic alkalosis is expected. (Choice C) Duodenal atresia, characterized by the double bubble sign (dilated stomach and duodenum) on x-ray, presents with bilious vomiting after initiation of feeds. Patients do not have yellow, seedy stools (as this infant does) because feeds cannot pass through the duodenum. double bubble sign (Choice D) Hirschsprung disease causes abdominal distension, feeding intolerance, and failure to pass meconium within 48 hours of birth. Milder disease may be diagnosed later in life, but patients typically have a history of chronic constipation and poor weight gain. (Choice E) Premature infants are at risk for intraventricular hemorrhage, which can cause a rapidly enlarging head circumference (not seen in this patient) due to obstructive hydrocephalus and symptoms of increased intracranial pressure (eg, nonbilious vomiting). This patient's tense and distended abdomen indicates a gastrointestinal rather than neurologic etiology. Educational objective: Bilious emesis and abdominal distension in a preterm neonate are highly suggestive of necrotizing enterocolitis. Abdominal x-ray findings include pneumatosis intestinalis (intramural air) and portal venous air. References: Feeding practices and necrotizing enterocolitis. (http://www.ncbi.nlm.nih.gov/pubmed/23415260) A clinical perspective of necrotizing enterocolitis: past, present, and future. (http://www.ncbi.nlm.nih.gov/pubmed/23415262)

A 3-Week-Old Boy in the Neonatal Intensive Care Unit Has