Division of Pediatric General, Thoracic and Fetal Surgery

A Guide to Your Child's Surgery

Our Surgery Guide will help you and your family prepare for your child's upcoming surgery, outlining what to expect from the first pre-op visit all the way through to her discharge.

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Pyloric Stenosis


Pyloric stenosis (or infantile hypertrophic pyloric stenosis) is a condition that causes severe vomiting in the first few months of life. There is narrowing (stenosis) of the opening from the stomach to the intestines, due to enlargement (hypertrophy) of the muscle surrounding this opening (the pylorus, meaning "gate"), which spasms when the stomach empties.

Illustration demonstrating pyloric stenosis

Signs and Symptoms

Pyloric stenosis is a problem that affects babies between 2 and 8 weeks of age and causes forceful vomiting that can lead to dehydration. It is one of the most common problems requiring surgery in newborns. It affects 2-3 infants out of 1,000.

Babies with this condition usually have progressively worsening vomiting during their first weeks or months of life. The vomiting is often described as "non bilious" and "projectile vomiting", because it is more forceful than the usual spit ups commonly seen at this age.

Some infants also experience poor feeding and weight loss, but others demonstrate normal weight gain. Dehydration can also occur which may cause the baby to sleep excessively, to cry without tears, or have fewer wet or dirty diapers during a 24-hour period.

Constant hunger, belching, and colic are other possible signs of pyloric stenosis because the baby is not able to eat properly. Dehydration and electrolyte imbalance are common problems and can prolong a hospital stay.


Diagnosing pyloric stenosis is made after taking a careful medical and family history, a physical examination and is often supplemented by radiographic studies. There should be suspicion of pyloric stenosis in any young infant with severe vomiting.

On exam, palpation of the abdomen may reveal a mass in the upper central region of the abdomen. This mass, which consists of the enlarged pylorus, is referred to as the “olive,” and is sometimes evident after the infant is given formula to drink.

Feeling the mass by palpation is a diagnostic skill requiring much patience and experience. There are often palpable (or even visible) peristaltic waves due to the stomach trying to force its contents past the narrowed pyloric outlet.

In addition to a complete history and physical exam, certain diagnostic procedures are necessary in order to make the diagnosis of pyloric stenosis:

Traditional X-rays of the abdomen are not useful in diagnosing pyloric stenosis, except when needed to rule out other potential problems.


Surgery is necessary to treat pyloric stenosis. The danger of pyloric stenosis is not just the vomiting, but the resulting dehydration and electrolyte disturbances that have deep impact on a developing baby.

Therefore, the baby must be initially stabilized by correcting the dehydration and electrolyte imbalance with IV fluids and electrolyte supplementation. This can usually be accomplished in about 24-48 hours. Repeat labs will be done to ensure the electrolyte imbalance is corrected.

The baby will not be able to breast or bottle feed until the surgery has been performed to correct the pyloric stenosis. Many children are fussy in this pre-surgery time because they cannot eat, but it is extremely important to minimize the chances that they vomit. As a result, children with pyloric stenosis will be maintained on IV fluids to keep them hydrated before surgery.


Surgery for pyloric stenosis is done once lab results are acceptable. The medical name of the surgery is pyloromyotomy, in which surgeons divide the muscle of the pylorus to open up the gastric outlet.

At the Children’s Hospital of Philadelphia, the pyloromyotemy is done through small incisions and with tiny scopes (laparoscopic). By doing laparoscopic surgery, we can minimize scarring, decrease potential infections and improve recovery time for children.

A few hours after the surgery, the child will be able to start feeding again. Some vomiting may be expected during the first days after surgery as the gastro-intestinal tract settles.

If vomiting continues we may prescribe an antacid. The stomach lining can become inflamed with the persistent vomiting. The antacid will help to protect the stomach and can be discontinued at the post-operative visit.

There is a chance that the child may have gastroesophageal reflux (GER). This will be diagnosed after surgery if the child is still having problems with frequent spitting up. You should follow up with your primary care provider to have further evaluation for gastroesophageal reflux.

Long-term prognosis

Pyloric stenosis is unlikely to reoccur. Babies who have undergone surgery for pyloric stenosis should have no long-term effects from it.

Contact us

To make an appointment to have your child evaluated by CHOP’s Division of Pediatric General , Thoracic and Fetal Surgery, please call 215-590-2730. 

Created by: Gina Kroeplin, MSN, CRNP & Jocelyn Gmerek, MSN, CRNP
Reviewed by: Pable Laje, MD
April 2012

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