This 6 week-old female patient presented with projectile vomiting. The ultrasound shows an elarged pylorus (click image for arrows). The length (green line) was 16mm (upper limit of normal 14mm), and the muscle thickness (orange line) was 4mm (upper limit of normal 3mm). This image also shows the “antral nipple sign” – redundant pyloric mucosa protruding into the gastric antrum, and the “cervix sign” – indentation of the pylorus into the fluid-filled antrum. The most telling sign, however, was that no gastric contents were seen to pass through the pylorus at any time during the examination.

Pyloric stenosis affects males 4-5 times more ofen than females. It occurs between 4-8 weeks of life, and presents with nonbilious projectile vomiting. There may be a positive family history. Ultrasound findings include: “target sign” (hypertrophied hypoechoic muscle surrounding echogenic mucosa); elongated pylorus with thickened muscle; “cervix sign”; “antral nipple sign”; exaggerated peristalsis; and failure of the pylorus to open.

Reference: Dähnert W. Radiology Review Manual, 5th edition, Lippincott, Williams & Wilkins, 2003.

Credit: Dr Laughlin Dawes