Hypertrophic pyloric stenosis

Classic triad of an infant 2-8 weeks of age coming with

  • Projectile non bilious vomiting
  • Oliva like mass palpated
  • Hypochloremic metabolic alkalosis

US is the main imaging modality to diagnose pyloric stenosis.

Scanning technique:

  • Find medially to gallbladder

  • Rolling the child to right lateral decubitus position and feeding the child with some fluid will make visualization of the pylorus better

Normal appearance in US

Basic anatomy of the pylorus.

Basic anatomy of the pylorus in transverse.

Ultrasound of a normal Pylorus

In transverse, the thin rim of hypoechoic muscle is typical of a normal Pylorus.

Pyloric stenosis

  • 2 numbers to remember: 3 and 14 mm
  • 3 mm wall thickness (yellow), 14 mm length of pylorus (pink)



  • Usually surgical (open or lap pyloromyotomy)
  • For those unsuitable, IV or oral atropine maybe used, but it will prolonged hospitalization and follow up.

Watch this video:


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