Children's Hospital Colorado

Hypertrophic Pyloric Stenosis

What is hypertrophic pyloric stenosis?

Pyloric stenosis occurs when the outlet of the stomach closes down, preventing normal movement of stomach contents into the small bowel. This condition is a common cause of infants vomiting undigested formula or breast milk.

How does hypertrophic pyloric stenosis cause children to vomit?

As a child eats, food travels from his or her mouth down the esophagus and into the stomach. The stomach acts as a reservoir, which slowly releases food into the small intestine.

However, in a child with pyloric stenosis the muscle that controls the flow of food from the stomach into the first part of the small intestine becomes enlarged, narrowing the outlet of the stomach. This narrowing inhibits food from passing into the small intestine and causes the infant to vomit.

If left untreated, hypertrophic pyloric stenosis can cause:

  • Dehydration
  • Electrolyte imbalance 
  • Lethargy

What causes hypertrophic pyloric stenosis?

This condition is caused by multiple factors including an infant’s genetics and environment.

Who gets hypertrophic pyloric stenosis?

Pyloric stenosis is:

  • Fairly common, affecting about 1 out of 500 live births
  • Four times more common in males than females 
  • Tends to run in families 

Helpful resources

Learn about the pediatric surgeons at Children’s Hospital Colorado.

What are the signs and symptoms of hypertrophic pyloric stenosis?

Infants who develop pyloric stenosis appear healthy during the first one or two weeks of life.

Between the third and fifth week of life, infants:

  • Begin to regurgitate or spit up formula and small amounts of breast milk.
  • Have more frequent and forceful episodes of vomiting, often prompting one or more visits to the pediatrician and changing formulas. 

Over the next few days:

  • The child’s vomiting becomes more forceful and sometimes projectile.
  • After vomiting the infant remains hungry and otherwise appears well.

What tests are used to diagnose hypertrophic pyloric stenosis?

When you visit Children’s Hospital Colorado, doctors will take a medical history and perform the following tests to determine if your child has hypertrophic pyloric stenosis. They include a:

  • Physical exam
  • Ultrasound
  • Upper gastrointestinal (UGI) study: This study is done when an ultrasound isn’t available, or if there is a lot of gas in the child’s intestines that can obscure the image of the pyloric channel.

How do doctors at Children’s Hospital Colorado diagnosis an infant with hypertrophic pyloric stenosis?

To make a diagnosis, doctors perform a physical examination and order various tests to determine whether or not an infant has pyloric stenosis.

  • Physical exam may show the infant with dry lips and mouth, absence of tears when crying and, if diagnosed late, lethargy.
  • An ultrasound study shows the enlarged pyloric muscle.
  • An UGI study shows the enlarged stomach with a narrow pyloric channel.
  • Abnormal blood stream electrolyte levels are common.

How is hypertrophic pyloric stenosis treated?

If your infant is diagnosed with this condition, he or she will likely require a bowel rest (to prevent vomiting the infant won’t eat or drink) and intravenous fluid. The goal is to correct any electrolyte imbalance before surgery.

Pyloric stenosis surgery

Pediatric surgeons use a minimally-invasive technique called laparoscopic pyloromyotomy. The goal of surgery is to open the enlarged muscle that blocks the outlet of the stomach. Minimally-invasive surgery allows your child to heal faster and with less pain.

  1. The surgeon makes a small incision in the infant’s belly button, inflates the abdominal cavity with air and then inserts a small camera to see inside the abdomen.
  2. Two incisions 3 mm long are made in the upper right and left abdominal wall to insert the additional instruments.
  3. Next, the surgeon cuts the outside of the pyloric muscle to allow the inner lining of the pyloric channel to bulge through the blockage and open the outlet of the stomach.
  4. Once this is done, the stomach empties into the small bowel and the digestive function returns to normal. 
  5. Finally, the surgeon closes the incisions. 

Most infants are discharged within 24 to 48 hours after surgery.

Why choose Children’s Hospital Colorado for your child’s hypertrophic pyloric stenosis?

Our pediatric surgeons are experienced in minimally-invasive surgical procedures

Our board-certified pediatric surgeons are trained and experienced in a wide variety of minimally-invasive laparoscopic procedures, including laparoscopic pyloromyotomy. Minimally-invasive surgery reduces your infant or child’s healing time, and pain and scars.

Pediatric anesthesiologists keep babies safe

Before and during surgery, our anesthesiologists put children into a sleep-like state that keeps them pain-free. Our anesthesiologists are specially trained to care for kids who have different needs than adults before, during and after anesthesia. Before surgery, parents meet with a pediatric anesthesiologist, who will ease any concerns and answer all of their questions. 

Contact us

Pediatric General Surgery 
Phone: 720-777-6571 
Admin Fax: 720-777-7271


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