Clinical Scenario:
A 12-day-old male infant, born at 34 weeks of gestation with a birth weight of 1.8 kg, has been receiving formula feeds. He develops increasing feed intolerance followed by persistent vomiting, progressive abdominal distension and passage of bloody stools over 2 days. On examination, he is pale and mildly dehydrated. His abdomen is markedly distended and tender.
An abdominal radiograph demonstrates multiple bubbly and linear lucencies within the bowel wall, with no evidence of free intraperitoneal air.
What is the most likely diagnosis?
A. Hirschsprung-associated enterocolitis
B. Intestinal malrotation with midgut volvulus
C. Necrotizing enterocolitis
D. Neonatal sepsis with paralytic ileus
E. Spontaneous intestinal perforation
Correct answer & Explanation:
Correct answer: C. Necrotizing enterocolitis
Explanation
This infant has several major risk factors and characteristic clinical features of necrotizing enterocolitis (NEC):
- Prematurity (34 weeks)
- Low birth weight
- Enteral feeding, particularly formula feeding
- Feeding intolerance and vomiting
- Progressive abdominal distension and tenderness
- Bloody stools
The key radiological finding is pneumatosis intestinalis, seen as linear or bubbly collections of gas within the bowel wall. It results from gas entering the intestinal wall through damaged mucosa and is a characteristic radiological feature of NEC.
The absence of free intraperitoneal air suggests that intestinal perforation has not occurred, although NEC can progress to perforation.
Why the other options are incorrect
A. Hirschsprung-associated enterocolitis — Incorrect:
This can cause abdominal distension and bloody diarrhea, but the infant’s prematurity, feeding history and particularly pneumatosis intestinalis strongly favor NEC.
B. Intestinal malrotation with midgut volvulus — Incorrect:
Typically presents with bilious vomiting and can rapidly cause intestinal ischemia. Pneumatosis intestinalis is not the characteristic radiological finding.
D. Neonatal sepsis with paralytic ileus — Incorrect:
Sepsis may cause ileus and abdominal distension, but it does not explain pneumatosis intestinalis and bloody stools as well as NEC.
E. Spontaneous intestinal perforation — Incorrect:
Spontaneous intestinal perforation usually presents with pneumoperitoneum/free intraperitoneal air. Pneumatosis intestinalis is not its defining radiological feature.
Exam Clue:
Premature infant + feeding intolerance + abdominal distension + bloody stool + pneumatosis intestinalis = NEC until proven otherwise.
A useful distinction is:
Pneumatosis intestinalis → NEC
Portal venous gas → severe NEC
Pneumoperitoneum → intestinal perforation/advanced NEC
