What diagnostic test confirms intestinal obstruction in a newborn with bilious vomiting, a distended abdomen, and x-ray findings of dilated loops with no distal gas?

Diagnostic Test for Distal Intestinal Obstruction in Newborns

Contrast enema is the diagnostic imaging procedure of choice to confirm the diagnosis in this newborn with distal bowel obstruction. 1

Clinical Reasoning

The clinical presentation described—bilious vomiting, distended abdomen, and x-ray showing dilated loops with no distal gas—indicates a distal bowel obstruction rather than a proximal obstruction. 1 This distinction is critical because it determines the appropriate diagnostic pathway:

Why Contrast Enema is the Answer

• Contrast enema is specifically recommended by the American College of Radiology as the diagnostic imaging procedure of choice when there is suspected distal obstruction. 1

• The absence of distal gas on plain radiographs with multiple dilated bowel loops is the classic presentation requiring contrast enema to differentiate between structural causes (ileal atresia, colonic atresia) and functional causes (meconium plug, Hirschsprung disease, meconium ileus). 1

• In congenital atresia cases, the lack of contents moving through the bowel results in a microcolon, which is best demonstrated by contrast enema. 1

• Research confirms that contrast studies form the backbone of investigation for bilious vomiting, with a positive predictive value of 85.7% for accurate prediction of surgical findings. 2

What NOT to Do

• Upper GI series is NOT indicated for suspected distal obstruction—there is no relevant literature supporting its use in this scenario. 1

• Ultrasound is NOT supported by current evidence for evaluating neonates with suspected distal bowel obstruction. 1, 3

• Nuclear medicine gastroesophageal reflux scan has no role in evaluating suspected distal obstruction. 1

Common Pitfall to Avoid

Do not confuse this presentation with proximal obstruction (double bubble or triple bubble with no distal gas), where contrast enema would be inappropriate. 1 In proximal atresia with the classic double or triple bubble sign and absent distal gas, surgery is typically performed without contrast enema, as the diagnosis is clear from plain films alone. 1

Differential Diagnoses Confirmed by Contrast Enema

The contrast enema will help differentiate between:

• Ileal atresia (most common structural cause) 1
• Meconium ileus (may be therapeutic as well as diagnostic) 1
• Hirschsprung disease (may require subsequent rectal biopsy) 1
• Meconium plug syndrome (functional, requires only observation) 1