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Pyloric stenosis

Definition: Pyloric stenosis is a condition where the passage between the stomach and the small intestine (the pylorus) becomes narrowed due to hypertrophy and hyperplasia of the pyloric sphincter muscle. This leads to obstruction and is most commonly seen in infants.


  • Most commonly affects infants between 2-8 weeks old.
  • More prevalent in males than females, with a 4:1 ratio.
  • There is a genetic predisposition; it can run in families.


  • The exact cause is unknown, but it is thought to be multifactorial, involving genetic, environmental, and hormonal factors.
  • Hypertrophy and hyperplasia of the pyloric muscle lead to narrowing of the pyloric canal.
  • This obstruction results in forceful vomiting, dehydration, and electrolyte imbalances.

Clinical Features:

  • Progressive, projectile vomiting that may be blood-tinged.
  • The vomiting typically occurs shortly after feeding, and despite vomiting, infants are usually hungry.
  • Palpable ‘olive’ mass in the right upper quadrant of the abdomen.
  • Visible gastric peristalsis in severe cases.


  • History and physical examination are paramount. A thorough feeding history and pattern of vomiting are essential.
  • Ultrasound is the diagnostic modality of choice, showing elongation and thickening of the pylorus.
  • Blood tests may show hypochloremic metabolic alkalosis due to loss of gastric acid from vomiting.


  • Initial treatment focuses on correcting dehydration and electrolyte imbalances with IV fluids.
  • Surgical intervention (pyloromyotomy) is the definitive treatment where the outer layer of the pyloric muscle is cut to relieve the obstruction.
  • Postoperative care includes gradual reintroduction of feeding and monitoring for complications such as infection or hernia.


  • If left untreated, pyloric stenosis can lead to severe dehydration, weight loss, and electrolyte imbalances.
  • Postoperative complications include wound infections, incomplete pyloromyotomy, or mucosal perforation.


  • With appropriate and timely treatment, the prognosis is excellent.
  • Most infants have prompt relief of symptoms post-pyloromyotomy and can resume normal feeding.


  • There are no known preventive measures, given the unclear etiology.

Key Points for Practice:

  • Pyloric stenosis should be suspected in any young infant with projectile vomiting.
  • Prompt recognition and treatment are essential to prevent complications.
  • Multidisciplinary management, involving paediatricians, surgeons, and nutritionists, is often required for optimal patient care.

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