IS Case 338: Hypertrophic pyloric stenosis

Scott Cassar, MD

Imaging Sciences, URMC

Imaging Sciences URMC 2009
Publication Date: 2009-09-16


Patient is a one-month-old, first born, male with projectile vomiting.


The pylorus is enlarged measuring 2.1 cm long and 0.5 cm thick.


Hypertrophic pyloric stenosis is a hypertrophy of the pylorus muscle resulting in a proximal foregut obstruction. The etiology is unknown. First born males, most commonly after the third week of life, are affected with nonbilious vomiting as the initial presentation.

Physical exam can reveal a palpable "olive" in the left upper abdominal quadrant and a visible gastric peristaltic wave may be observed after feeding. Diagnosis is usually confirmed with ultrasound which has a 95% sensitivity. The sonographic criteria for diagnosis includes a pyloric thickness of ≥ 3mm or an overall pyloric length of > 14mm. (This is easily remembered by remembering the mathematical constant Pi =3.14, Pi-loric Stenosis). An upper GI contrast examination may also be performed which would demonstrate an elongated pyloric channel, a pylorus which bulges into the antrum, and parallel streaks of barium in the narrowed channel.

Once confirmed, the treatment of choice is pyloromyotomy which is performed through a small anterior abdominal wall incision. The pylorus is split without cutting the mucosa and the incision is closed.


  1. Kliegman RM, Berhrman RE, Jenson HB, Stanton B. Nelson Textbook of Pediatrics. 18th ed., Saunders, 2007.
  2. Rumack C, Wilson S, Charboneau JW. Diagnostic Ultrasound. 3rd ed., Vol 2. Mosby, 2005.

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