A 3-week-old male infant presents with projectile non-bilious vomiting after feeds for the past 7 days. He appears hungry after vomiting. On examination, a hard olive-shaped mass is palpable in the right epigastrium. Blood gases show: pH 7.55, pCO2 48 mmHg, bicarbonate 38 mEq/L, chloride 85 mEq/L, potassium 2.8 mEq/L. What is the CORRECT management sequence?
- A Emergency surgical pyloromyotomy (Ramstedt's) immediately
- B IV dextrose saline without KCl, then pyloromyotomy
- C Endoscopic balloon dilation of pylorus
- D IV normal saline + KCl replacement to correct metabolic alkalosis, THEN elective pyloromyotomy ✓
Explanation
Hypertrophic pyloric stenosis presents with hypochloremic, hypokalemic metabolic alkalosis (paradoxical aciduria) due to loss of HCl in vomitus and renal compensatory H+ wasting. Surgery (Ramstedt's pyloromyotomy) is NEVER an emergency — it is a medical emergency to correct the metabolic alkalosis first. IV normal saline corrects dehydration and chloride depletion; KCl supplementation corrects hypokalemia. Pyloromyotomy is performed only after metabolic correction (bicarbonate <30 mEq/L, chloride >100 mEq/L, urine output adequate). Premature surgery under alkalotic conditions carries anesthesia risk (apnea).
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.