Pyloromyotomy (Ramstedt)
What the Examiner Expects
Longitudinal division of the hypertrophied pyloric muscle in infants with hypertrophic pyloric stenosis, performed either open (RUQ transverse incision or periumbilical) or laparoscopically. The examiner expects you to make the diagnosis clinically (non-bilious projectile vomiting, dehydration, palpable olive in a 2–8 week old), confirm with ultrasound (pyloric muscle thickness > 3 mm, length > 15 mm), and correct the metabolic derangement BEFORE surgery: these infants have hypochloremic, hypokalemic metabolic alkalosis from vomiting gastric HCl. Resuscitation with NS (isotonic saline) with KCl supplementation until the chloride and potassium normalize is mandatory before anesthesia. The myotomy extends from the pyloric vein of Mayo to the antral-pyloric junction, dividing the circular muscle fibers until the submucosa bulges freely.
Key Examiner Focus Points
- Indicated for infantile hypertrophic pyloric stenosis
- Classic presentation: non-bilious projectile vomiting in a 2–8 week old; palpable olive-shaped mass
- Correct hypochloremic, hypokalemic metabolic alkalosis BEFORE surgery
- Myotomy divides the hypertrophied pyloric muscle down to submucosa without entering mucosa
- Duodenal perforation is the most important intraoperative complication to recognize
Common Curveballs
After completing the myotomy, you notice bubbles at the duodenal end when checking with an air insufflation test
Mucosal perforation — most commonly at the duodenal end of the myotomy. Close the perforation with absorbable sutures, cover with omentum, and perform the myotomy on the opposite (180° rotated) side of the pylorus. Failure to recognize this intraoperatively leads to peritonitis.
The infant has a serum bicarbonate of 34 and potassium of 2.8 — the surgeon wants to go to the OR now
No. This infant is not adequately resuscitated. The metabolic alkalosis must be corrected first (bicarbonate should normalize, chloride and potassium should be replenished). Operating on an infant with uncorrected metabolic alkalosis risks postop apnea from the alkalosis (decreased respiratory drive). Resuscitate with NS + KCl and recheck labs.
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