Ultrasound for hypertrophic pyloric stenosis

  • Patient preparation: none
  • Contrast used: none
  • Technique: linear transducer
    — 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 to provide an acoustic window, but do not 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. Note that the lower esophageal sphincter can mimic appearance of normal pylorus if you are not lined up correctly here
  • Images to obtain: document the pylorus in transverse and sagittal grayscale images, document the relationship of the superior mesenteric vein (SMV) / superior mesenteric artery (SMA) in transverse color and spectral doppler images
  • Looking for:
    — Elongated and thickened pylorus – pathological measurements needed to diagnose pyloric stenosis are the pylorus must be > 17 mm in length and the width of one wall must be > 3.5 mm
    — Relationship of the SMV and SMA to rule out malrotation. The SMV should be anterior and to the right of the SMA. If it is not in the correct position the possibility of malrotation is greatly increased and you should do an upper GI to rule out malrotation
  • Post procedure tasks: none