Pyloric Stenosis

Pyloric stenosis is an uncommon condition in infants where the muscle at the bottom of the stomach (pylorus) thickens, blocking food from entering the small intestine. This blockage causes forceful, projectile vomiting, usually starting a few weeks after birth. It prevents babies from getting enough nutrition and can lead to dehydration and weight loss.

What is Pyloric Stenosis?

Pyloric stenosis is a condition affecting infants, typically between 2 and 8 weeks old, where the muscle at the stomach's exit (pylorus) becomes abnormally thick and narrow. This narrowing prevents milk or food from passing into the small intestine, leading to significant feeding problems and forceful vomiting.

The pylorus is a valve-like muscle that controls the flow of food from the stomach into the first part of the small intestine (duodenum). In pyloric stenosis, this muscle thickens and enlarges, creating a much smaller opening. Think of it like a clogged drainpipe that food struggles to pass through. Because the opening is so narrow, the stomach muscles have to work harder to push food through. Eventually, the food cannot pass at all, and it is forcefully vomited back up. This condition is uncommon, affecting about 3 out of 1,000 live births in the United States (0.3%). It is more common in boys than girls. (MedlinePlus, Mayo Clinic)

Symptoms

The main symptom of pyloric stenosis is forceful, projectile vomiting that often occurs after feeding. Infants may also show signs of constant hunger, dehydration, and poor weight gain or weight loss. These symptoms usually appear between 3 and 6 weeks of age, though they can start earlier or later.

Vomiting is the most noticeable symptom. It is often described as "projectile" because it can shoot several feet away from the infant. Unlike regular spit-up, this vomiting is forceful and usually happens shortly after a feeding. The vomit typically does not contain bile (a greenish fluid), meaning it's not coming from further down the digestive tract. Despite vomiting, babies with pyloric stenosis often remain hungry and want to feed again soon after. Because they cannot keep food down, they may not gain weight or might even lose weight. You might also notice fewer wet diapers and less frequent bowel movements, which are signs of dehydration and constipation. Sometimes, you can see wave-like contractions across your baby's upper abdomen as their stomach tries to push food through the narrowed pylorus. (MedlinePlus, Mayo Clinic)

Causes & risk factors

The exact cause of pyloric stenosis is not fully understood, but it is believed to involve a combination of genetic and environmental factors. Several risk factors increase an infant's likelihood of developing this condition, including sex, family history, and exposure to certain antibiotics.

While the precise cause remains unknown, research suggests that genetics play a role. Pyloric stenosis tends to run in families, and if a parent had the condition, their child has a higher chance of developing it. It is also more common in firstborn boys, affecting about 4 times as many boys as girls. (MedlinePlus, Mayo Clinic) Certain risk factors have been identified. Infants exposed to specific antibiotics, such as erythromycin or azithromycin, either directly in the first few weeks of life or if their mother took them late in pregnancy or while breastfeeding, have a higher risk. Some studies also suggest a link between premature birth and pyloric stenosis, as well as smoking during pregnancy. (Mayo Clinic)

How it's diagnosed

Pyloric stenosis is typically diagnosed based on a physical exam and imaging tests. A doctor will look for an "olive-shaped" lump in the baby's abdomen and confirm the diagnosis with an ultrasound. Blood tests may also be done to check for dehydration and electrolyte imbalances.

During a physical examination, the doctor may be able to feel a small, firm, olive-shaped lump in your baby's abdomen. This lump is the thickened pylorus muscle. The doctor will also look for signs of dehydration, such as sunken eyes, dry mouth, and reduced skin elasticity. An ultrasound is the primary imaging test used to confirm pyloric stenosis. This non-invasive test uses sound waves to create images of the pylorus, allowing the doctor to measure its thickness and see if the opening is narrowed. Blood tests are also important to check for dehydration and imbalances in electrolytes, such as sodium and potassium, which can occur due to frequent vomiting. (MedlinePlus, Mayo Clinic)

Treatment options

The standard and most effective treatment for pyloric stenosis is a surgical procedure called pyloromyotomy. Before surgery, doctors will stabilize the infant by correcting any dehydration and electrolyte imbalances. The surgery opens the narrowed pylorus, allowing food to pass normally into the small intestine.

Before surgery, it is crucial to rehydrate the infant and correct any electrolyte imbalances caused by vomiting. This is usually done by giving fluids and electrolytes intravenously (through a vein). Once the baby is stable, the pyloromyotomy can proceed. During a pyloromyotomy, the surgeon makes a small incision in the thickened pyloric muscle, but not through the inner lining of the stomach. This opens up the channel between the stomach and the small intestine, allowing food to pass freely. The surgery is often performed using minimally invasive techniques, such as laparoscopy, which involves smaller incisions and a faster recovery. (MedlinePlus, Mayo Clinic, Cochrane Library)

Recovery & outlook

Recovery from pyloric stenosis surgery (pyloromyotomy) is usually quick and complete, with an excellent long-term outlook. Most infants can start feeding again within hours after the procedure and typically go home within a day or two. The surgery effectively resolves the blockage, allowing normal feeding and growth.

After a pyloromyotomy, infants usually recover very quickly. They can often begin small, frequent feedings within a few hours. Vomiting may continue for a day or two as the digestive system adjusts, but it typically subsides completely. Most babies are able to go home within 24 to 48 hours after the surgery. The long-term outlook for infants who undergo surgery for pyloric stenosis is excellent. The procedure is highly successful in resolving the obstruction, and recurrence is extremely rare. Once the pylorus is opened, infants can typically feed normally, gain weight, and develop without further issues related to the condition. (MedlinePlus, Mayo Clinic, Cochrane Library)

When to see a doctor

You should see a doctor immediately if your infant experiences forceful, projectile vomiting after feedings, especially if it's happening repeatedly. Other urgent signs include constant hunger despite vomiting, poor weight gain, fewer wet diapers, or any signs of dehydration like lethargy or sunken soft spots.

Early diagnosis and treatment of pyloric stenosis are important to prevent serious complications like severe dehydration and malnutrition. If your baby shows any of the symptoms mentioned, do not wait to seek medical attention. Specifically, look out for: * Vomiting that is forceful and shoots out (projectile vomiting). * Vomiting that occurs after every feeding or most feedings. * Your baby seems constantly hungry even after vomiting. * Your baby is not gaining weight or is losing weight. * Fewer wet diapers than usual, or signs of dehydration such as crying without tears, a dry mouth, or a sunken soft spot on their head. These symptoms warrant an immediate visit to your pediatrician or an urgent care facility. (MedlinePlus, Mayo Clinic)

Frequently asked questions

How common is pyloric stenosis?

Pyloric stenosis is an uncommon condition, affecting about 3 out of every 1,000 live births in the United States (0.3%). It is more frequently seen in boys, particularly firstborn boys, than in girls. (MedlinePlus, Mayo Clinic)

Can pyloric stenosis be prevented?

Pyloric stenosis cannot be prevented because its exact cause is unknown. However, some risk factors, like certain antibiotic use in infants or mothers late in pregnancy, have been identified. Discuss any medication concerns with your doctor. (Mayo Clinic)

What happens if pyloric stenosis is not treated?

If left untreated, pyloric stenosis can lead to severe dehydration, malnutrition, and significant weight loss in infants. Without treatment, babies cannot absorb enough nutrients and fluids, which can become life-threatening. Prompt surgical correction is essential. (MedlinePlus, Mayo Clinic)

How long does recovery take after surgery?

Recovery after pyloric stenosis surgery (pyloromyotomy) is typically very quick. Most infants can start feeding again within hours of the procedure and are usually discharged from the hospital within 1 to 2 days. Full recovery, with normal feeding and weight gain, is expected shortly after. (Mayo Clinic, Cochrane Library)

Will my baby have long-term problems after pyloric stenosis surgery?

No, long-term problems after successful pyloric stenosis surgery are extremely rare. The surgery effectively resolves the blockage, allowing infants to feed normally, gain weight, and develop without any lasting issues related to the condition. The prognosis is excellent. (MedlinePlus, Mayo Clinic)

Is pyloric stenosis hereditary?

Pyloric stenosis does have a hereditary component. It tends to run in families, meaning if a parent or another close relative had the condition, there is an increased chance that an infant may also develop it. However, not all cases have a clear family history. (MedlinePlus, Mayo Clinic)

Sources

• MedlinePlus — Pyloric Stenosis
• Mayo Clinic — Pyloric Stenosis
• Cochrane Library — Pyloric Stenosis