Hypertrophic Pyloric Stenosis

  • Etiology: idiopathic hypertrophy of circular pylorus muscle leading to gastric outlet obstruction
  • AXR: caterpillar sign of peristaltic waves in stomach due to hyperperistalsis
  • US: pyloric muscle > 3.5 mm thick, pyloric channel > 17 mm long, minimal passage of fluid through pylorus
  • UGI: antral shouldering + pyloric beak / teat + tram track through pylorus all secondary to thickened pylorus
  • DDX: prostaglandin E induced gastritis, pylorospasm
  • Note: lower esophageal sphincter can mimic appearance of normal pylorus

Radiology Cases of Hypertrophic Pyloric Stenosis

Upper GI and US of hypertrophic pyloric stenosis
Lateral images from an upper GI exam (above) show delayed passage of barium out of the stomach due to a thickened and elongated pylorus. A tram track sign of barium in the pyloric channel was seen (upper left) along with pyloric muscle shouldering on the antrum along with a pyloric beak (upper right). Sagittal (lower left) and transverse (lower right) US of the pylorus shows marked thickening of the peripheral hypoechoic pyloric muscle which measures 4.5 mm thick, as compared to the thin central hyperechoic pyloric mucosa. Elongation of the pyloric channel was also noted, measuring 25 mm in length.

Surgery Cases of Hypertrophic Pyloric Stenosis

Surgical image of hypertrophic pyloric stenosis
Surgical image shows delivery of the pylorus which is thickened, firm and blanched as opposed to its normal small, soft and pink consistency.