Immediate Management of 5-Month-Old with Greenish Vomiting and Obstruction Signs
Direct Answer
Obtain an abdominal X-ray immediately as the first imaging study, followed by upper GI contrast series if obstruction is confirmed. 1, 2, 3
Clinical Context and Urgency
Greenish (bilious) vomiting in a 5-month-old infant represents a surgical emergency until proven otherwise because it indicates obstruction distal to the ampulla of Vater. 2, 3 This presentation demands urgent evaluation as conditions like malrotation with midgut volvulus can compromise intestinal blood supply and lead to bowel necrosis within hours. 3
Algorithmic Approach to Imaging
Step 1: Initial Abdominal Radiograph (Answer D)
Plain abdominal X-ray is the appropriate first imaging study to identify signs of intestinal obstruction including dilated bowel loops, air-fluid levels, and the pattern of gas distribution. 1, 2, 3
The radiograph helps determine the level of obstruction and guides subsequent imaging decisions. 1, 4
This is the standard initial approach recommended by the American College of Radiology for infants with suspected obstruction. 2, 3
Step 2: Upper GI Contrast Series (Answer A)
After the initial radiograph, an upper GI series is usually appropriate for infants older than 2 days with bilious vomiting to evaluate for malrotation and midgut volvulus. 1
The upper GI series directly images the stomach and small bowel, with the most critical finding being abnormal position of the duodenojejunal junction (ligament of Treitz), which indicates malrotation. 1
This study has 96% sensitivity for detecting malrotation, making it the reference standard for this diagnosis. 1
Why Other Options Are Incorrect
Lower GI Contrast (Answer B)
Contrast enema is NOT appropriate for initial evaluation of bilious vomiting in this age group. 1
Lower GI studies are reserved for suspected distal bowel obstruction (when radiographs show multiple distended loops with absent distal gas), not for bilious vomiting which suggests proximal or midgut pathology. 1
Barium enema for malrotation is less direct than upper GI series and has up to 20% false-negative rate. 1
Endoscopy (Answer C)
Endoscopy has no role in the acute evaluation of intestinal obstruction in infants. 1
While endoscopy may help in certain chronic conditions or for therapeutic interventions in adults, it is not part of the diagnostic algorithm for pediatric intestinal obstruction. 5
Critical Actions Required
Immediate surgical consultation must occur simultaneously with imaging workup, as bilious vomiting represents a potential surgical emergency. 3
Fluid resuscitation and nasogastric decompression should be initiated while diagnostic workup proceeds. 6, 5
Assess for associated conditions including abdominal distention, bloody stools ("currant jelly" appearance suggesting intussusception), and signs of peritonitis. 2, 3
Common Pitfalls to Avoid
Never delay evaluation of bilious vomiting waiting for "observation" or symptomatic treatment—this is a surgical emergency requiring immediate imaging. 2, 6
Do not skip the plain radiograph and proceed directly to contrast studies, as the X-ray provides crucial information about obstruction level and may reveal free air if perforation has occurred. 1, 2, 3
Do not confuse this with pyloric stenosis, which presents with non-bilious projectile vomiting in infants 2 weeks to 3 months old and would warrant ultrasound as the initial study. 1, 2