A 3-week-old male infant presents with projectile non-bilious vomiting after feeds, visible gastric peristalsis, and a palpable olive-like mass in the right hypochondrium. Ultrasound confirms hypertrophic pyloric stenosis (pyloric muscle thickness 4 mm, length 18 mm). Serum electrolytes show: Na 132, K 3.0, Cl 88, HCO3 32 mEq/L. What is the most critical step BEFORE definitive surgical treatment?
- A Immediate Ramstedt pyloromyotomy as it is a surgical emergency
- B Nasogastric decompression followed by atropine therapy to avoid surgery
- C IV fluid resuscitation with correction of hypochloraemic hypokalaemic metabolic alkalosis before surgery ✓
- D Upper GI contrast study to confirm diagnosis before ultrasound is definitive
Explanation
Hypertrophic pyloric stenosis is NOT a surgical emergency — it is a metabolic emergency requiring correction before anaesthesia. Repeated vomiting of gastric acid causes hypochloraemic, hypokalaemic metabolic alkalosis. Anaesthesia in alkalotic state carries risk of apnoea (central chemoreceptors blunted) and cardiac arrhythmias. IV 0.9% saline + 5% dextrose with KCl supplementation is given until serum Cl > 100 mEq/L, K > 3.5 mEq/L, and bicarbonate < 26 mEq/L. Only then is Ramstedt pyloromyotomy performed safely. Atropine therapy is an alternative but not standard-of-care for severe alkalosis. Ultrasound is diagnostic (muscle thickness > 3 mm, length > 14 mm).
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.