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Age: 6 weeks (born at 40 weeks)

Sex: Male

Indication: Projectile vomiting

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Case #10


  • Elongated pyloric channel measuring approximately 20 mm
  • Single wall muscle thickness of the pylorus measures 6 mm
  • No bulk fluid transit is observed from the stomach to the duodenum over 30 minutes of intermittent imaging


Hypertrophic pyloric stenosis

Sample Report

Elongated pyloric channel with increased pyloric wall thickness and no observed bulk fluid transit from the stomach to the duodenum over 30 minutes of intermittent imaging. These findings are consistent with hypertrophic pyloric stenosis.


  • Hypertrophic pyloric stenosis (HPS) is the most common surgical cause for vomiting in infants and classically presents with projectile, nonbilious emesis
  • HPS most commonly presents between 2-6 weeks of age and is more common in male, Caucasian, first-born infants
  • Ultrasound is key to making the diagnosis, with the following criteria:
    • Single wall (usually measure anterior wall) muscle thickness >3 mm – this is the most reliable measurement for making the diagnosis
    • Pyloric channel length >12 mm – this measurement is more difficult and some radiologists advocate a higher threshold of 15-17 mm to improve study specificity
    • Failure of the pylorus to relax and allow passage of fluid over a 30 minute period of intermittent observation
  • Other supportive findings include:
    • Distended stomach
    • Cervix-like protrusion of the hypertrophied pylorus into the antrum
  • In order to improve visualization (by displacing gas in the stomach) and test for peristalsis, it is common to administer fluid via NG tube for these cases
  • Management is usually surgical with pyloromyotomy
    • Following surgery, wall thickness should return to normal (<3 mm) within about 5 months, with the anterior wall returning to normal diameter earlier


Increased single wall muscle thickness (red dotted line) and elongated pyloric channel (yellow dotted line), supportive of a diagnosis of hypertrophic pyloric stenosis.

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