Clinical scenario: vomiting after feed | pyloric stenosis | treatment
A 4-week-old male infant presents with recurrent vomiting after feeds for 10 days. The vomiting has become progressively more forceful but remains non-bilious. His weight gain has been poor. On examination, he is mildly dehydrated. No palpable pyloric mass is appreciated.
Laboratory investigations show:
- Sodium: 132 mmol/L
- Potassium: 3.2 mmol/L
- Chloride: 94 mmol/L
- Bicarbonate: 30 mmol/L
Abdominal ultrasound shows: Pyloric muscle thickness: 3.8 mm, Pyloric channel length: 17 mm and Incomplete gastric emptying during the study
What is the most appropriate next step?
A. Start anti-reflux therapy and observe
B. Repeat ultrasound after 24–48 hours
C. Proceed to pyloromyotomy after stabilization
D. Perform upper gastrointestinal contrast study
E. Start nasogastric feeding
Correct answer & Explanation:
Correct answer: C. Proceed to pyloromyotomy after stabilization
Explanation:
This infant has hypertrophic pyloric stenosis (HPS).
The diagnosis is supported by:
- Typical age (2–8 weeks)
- Progressive projectile non-bilious vomiting
- Poor weight gain
- Ultrasound findings:
- Pyloric muscle thickness >3 mm
- Increased pyloric channel length (>15–18 mm)
- Poor gastric emptying
The infant has only mild biochemical abnormalities, so after appropriate hydration and correction of electrolytes, Ramstedt pyloromyotomy is the definitive treatment.
Why the other options are incorrect
A. Anti-reflux therapy
- GERD causes effortless regurgitation, not progressive projectile vomiting with abnormal pyloric measurements.
B. Repeat ultrasound
- May be considered if measurements are equivocal, but this ultrasound is diagnostic.
D. Upper GI contrast study
- Used when the diagnosis is uncertain or to evaluate other causes such as malrotation; it is not required here.
E. Nasogastric feeding
- Does not correct the mechanical obstruction.
High-yield postgraduate pearl
Ultrasound is the preferred diagnostic test for hypertrophic pyloric stenosis. A pyloric muscle thickness ≥3 mm and channel length ≥15–18 mm strongly support the diagnosis. However, clinical correlation is essential, especially in early disease where measurements may be borderline.
