Ultrasound for Hypertrophic Pyloric Stenosis

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

Contrast:
None

Technique:
Transducer - 5MHz linear
Position the patient with a pillow under the left side so the patient is in a right posterior oblique position. The stomach should have fluid in it. If the stomach is empty, give the patient some glucose water, but don't overdistend the stomach.

Line up the transducer transversely by getting the gallbladder and right kidney in the same image. From here, you should be able to see the pylorus. Check the relationship of the superior mesenteric vein (SMV) and superior mesenteric artery (SMA) transversely to rule out malrotation. The SMV should be to the right and superior to the SMA. Always check the kidneys for incidental pathology.

The pathological measurements need to diagnose pyloric stenosis are the pylorus must be 17 mm in length, and the width of one wall must be 3.5 mm. A mimic for HPS is gastritis. In HPS the wall is thick and the mucosa is normal. In gastritis the wall is normal and the mucosa is thick.

Views to Take:
Document the pylorus in longitudinal and transverse planes
Document the position of the SMV/SMA
Take a single longitudinal view of each kidney with measurements.

References:
See References Chapter.

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