Overview, Causes, & Risk Factors

Pyloric stenosis is a narrowing of the opening of the stomach, known as the pylorus, through which food and other stomach contents enter the small intestine. This narrowing occurs in newborns and must be corrected immediately with surgery so the baby can digest milk and thrive.

What is going on in the body?

The pylorus is a circular muscle. When an infant has pyloric stenosis, the pyloric muscle is enlarged, narrowing the entrance to the small intestine. This enlargement produces a partial obstruction or blockage at the pylorus. Over a period of time, the pylorus becomes inflamed and swollen producing even further obstruction. Although infants are born with pyloric stenosis, symptoms usually are not noticed until 2 or 3 weeks after birth.

What are the causes and risks of the condition?

Pyloric stenosis is a congenital defect, or condition present at birth. The exact cause of this condition is unknown. Pyloric stenosis affects more males than females (about 1 in 750 females and 1 in 150 males). It is the most common condition requiring surgery in the first 2 months of life. There is a 5% chance that a sibling of someone with pyloric stenosis will also have it and about a 25% chance that children of a mother with a history of pyloric stenosis will also have it.

Symptoms & Signs

What are the signs and symptoms of the condition?

At first, pyloric stenosis may cause a mild backflow of food from the stomach to the mouth and mild vomiting. After the symptoms have been present for about 1 week, the vomiting progresses to projectile vomiting. Projectile vomiting is a condition in which the baby vomits so hard that the material vomited may actually go several feet through the air. Usually vomiting occurs within 30 minutes after feeding. After vomiting, the baby usually acts extremely hungry again and wants another feeding. Vomiting may be blood tinged if it is very forceful. The vomit usually does not have greeen bile in it because the blockage is above the area of bile production.

Other signs may be present:

Diagnosis & Tests

How is the condition diagnosed?

The healthcare provider will do a physical exam and take a full history. The healthcare provider may ask such questions as:

The healthcare provider may be able to feel a small mass in the upper right side of the baby's abdomen. Blood may be taken from a vein, and a chem-7 blood test may reveal a salt imbalance. A blood test called a complete blood count, or CBC, may reveal high hemoglobin and hematocrit counts, indicating an increase in the amount of iron and blood volume. An abdominal ultrasound usually confirms the diagnosis of pyloric stenosis. Sometimes, x-rays of the upper gastrointestinal tract, called an upper GI series, may be done.

Prevention & Expectations

What can be done to prevent the condition?

This condition cannot be prevented. If there is a family history of pyloric stenosis, a new baby should be closely watched for any symptoms.

What are the long-term effects of the condition?

If treatment is prompt, there are usually no long-term side effects from pyloric stenosis. Recovery depends on the general health of the infant and how quickly a diagnosis and treatment were made.

What are the risks to others?

There are no direct risks of pyloric stenosis to others. This is not a contagious condition, but it can run in families.

Treatment & Monitoring

What are the treatments for the condition?

The treatment of choice for pyloric stenosis is a surgical procedure known as a pyloroplasty. Prior to surgery the first concern is to rehydrate the infant with intravenous fluids. A nasogastric tube may also be inserted through the nose and down into the baby's stomach to remove gastric juices prior to and during surgery. After general anesthesia is given, the surgeon makes an incision down to the mucosa lining of the pylorus and across it. This opens up the narrowed pylorus.

What are the side effects of the treatments?

There may be side effects from any surgery including risk of bleeding, infection, and even death. Any surgery in the abdomen can cause adhesions, which are pieces of tissue that develop during healing. Infrequently, adhesions can cause blockages in the intestines if they are in a place that allows them to compress part of the intestine. This can occur many years after the surgery. Anesthesia may cause stomach upset or allergic reactions.

What happens after treatment for the condition?

Usually an infant can start small feedings of clear liquids once the intestines start moving well again. This may be as soon as 4 to 6 hours after surgery. The baby will progress to formula or breast milk during the course of the next few days. A baby may need to stay in the hospital for a few days to continue IV fluids and to slowly progress to oral feedings. The chances of full recovery after surgery are excellent. Sometimes continued vomiting may occur after surgery, if symptoms progressed to severe dehydration and malnutrition before surgery. In this case, intavenous fluids may be continued until vomiting subsides.

How is the condition monitored?

Once the condition has been treated and an infant has recovered from surgery, there may be no need for monitoring. If vomiting continues or symptoms redevelop, it is important to contact the healthcare provider.