Hypertrophic Pyloric Stenosis (HPS)

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Etiology/Pathophysiology:
Thickening and elongation of the circular muscles of the pyloric canal with narrowing of the pyloric lumen.

Pathology:
Not applicable

Imaging Findings:
Plain abdominal films can show a peristaltic wave in the stomach, or evidence of a gastric outlet obstruction with a large dilated stomach.

Upper GI signs, which indirectly image the pyloric mass, include: (1) shoulder = mass effect on the lesser curvature of the gastric antrum, (2) teat = peristaltic waves encroaching on the mass and the shoulder, (3) beak = barium entering only the entrance of the pyloric canal, (4) string = barium extending into the narrowed and elongated pyloric canal, (5) U = upturned course of the pyloric canal towards the duodenum (6) track = parallel columns of barium in the pyloric canal produced by longitudinal infolding of the pyloric mucosa, (7) caterpillar = gastric contour distorted by multiple deep peristaltic waves, (7) mushroom = encroachment of the base of the duodenal bulb by the hypertrophic muscle mass.

US signs, which directly image the pyloric mass, include an anechoic ring of hypertrophied pyloric muscle surrounding the echogenic central mucosa.

DDX:

• Gastritis

References:

• Correlapedia

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