A 3-week-old male infant presents with projectile non-bilious vomiting after feeds, visible gastric peristalsis, and a palpable 'olive-shaped' mass in the right epigastrium. Electrolytes show: Na 132 mEq/L, K 2.8 mEq/L, Cl 88 mEq/L, HCO3 32 mEq/L. What is the MOST appropriate sequence of management?

• A Immediate pyloromyotomy — do not delay for metabolic correction
• B Endoscopic balloon dilation of the pylorus
• C Nasogastric suction alone for 48 hours then feed trial
• D Correct the hypochloraemic hypokalaemic metabolic alkalosis first, then pyloromyotomy (Ramstedt's operation) ✓

Explanation

Hypertrophic pyloric stenosis causes hypochloraemic, hypokalaemic metabolic alkalosis from prolonged vomiting of gastric acid. Surgery (Ramstedt's pyloromyotomy) is not an emergency — the infant must be adequately rehydrated and metabolic derangements corrected first (typically 24-48 hours of IV fluids with potassium supplementation) before anaesthesia, as uncontrolled alkalosis increases anaesthetic risk and apnoea risk. Once urine output is satisfactory and electrolytes normalised, surgery proceeds.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.