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Pyloric Ultrasound

What is pyloric ultrasound?

Pyloric ultrasound is a radiology exam used to diagnose pyloric stenosis in infants. Pyloric stenosis is an uncommon condition that prevents the stomach from emptying food into the small intestine. This can lead to projectile vomiting and other symptoms.

By using a special ultrasound transducer, this test can visualize internal body structures in a completely noninvasive way without exposing the baby to ionizing radiation (X-rays). Ultrasound has no known harmful side effects, and it is a fast, noninvasive method for doctors to evaluate soft tissues that don’t show up on regular X-ray exams. This technique is especially useful to visualize the appearance, size, consistency, and shape of internal organs and abnormalities.

The ultrasound transducer sends out small pulses of high-frequency sound waves. When pressed against the skin, the transducer transmits the sound waves, that bounce off structures in the body. The transducer picks up the rebounding sound waves, and, with the help of a computer, the characteristics of a structure can be determined.

The pylorus is a muscular valve between the stomach and small intestine. Normally, the pylorus relaxes to let food empty from the stomach into the small intestine. With pyloric stenosis, the muscle is thickened and does not function properly. This condition typically occurs in infants 3 to 5 weeks old. Pyloric stenosis is usually corrected by surgery.
Symptoms of pyloric stenosis include:

  • Forceful vomiting
  • Weight loss
  • Dehydration
  • Persistent hunger

If your baby has symptoms that indicate possible pyloric stenosis, your pediatrician may recommend a pyloric ultrasound to help confirm the diagnosis.


  • Pyloric ultrasound is an inexpensive, fast, and noninvasive way to assess structures inside the abdomen, including the pylorus.
  • Ultrasound does not expose the baby to any ionizing radiation (X-rays).
  • Ultrasound is very safe and has no side effects.
  • Contrast agents are not used for this ultrasound exam.
  • Ultrasound can detect soft tissue abnormalities that cannot be seen with regular X-ray exams.


  • The use of diagnostic ultrasound has no known risks or harmful effects.
  • Pyloric ultrasound is performed at ARA Children’s Imaging Center, a hospital, or a medical center.
  • You will be asked to remove your baby’s clothing.
  • You will be able to accompany your baby during the entire exam.
  • The baby will be placed on their back on an exam table. You may need to change your baby’s position during the exam to get a better view of the pylorus.
  • A warm gel will be placed on the area to be examined. The gel creates a sealed contact between the skin and the ultrasound probe. This eliminates any air pockets that may interfere with imaging. The probe will be moved around to capture images from different locations.
  • The technologist or doctor performing the exam may have to apply pressure with the probe to the body part being examined. If the area is tender, the baby might experience some discomfort.
  • When the exam is finished, you may dress your baby and return home.
  • Your baby should not have any feeding for 4 hours before the pyloric ultrasound.

To schedule a pyloric ultrasound, please speak to your health care provider and call our scheduling team at (512) 453-6100 or toll free at (800) 998-8214. A referral from your health care provider is required to make an appointment.

A radiologist, a physician specifically trained to interpret radiological examinations, will analyze the images and send a signed report to the provider who referred you to ARA. Your health care provider will then share the results with you. Your report will also be available on the patient portal within 3 business days.


Pediatric Imaging At ARA is designed with the child in mind

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