Pyloric Stenosis: Symptoms, Causes and Treatment


Pyloric stenosis is a rare condition that occurs when the passage between the stomach and the small intestine narrows. It usually occurs in infants and can cause obstruction, leading to projectile vomiting, abdominal cramps, dehydration, and hunger.

Experts believe that pyloric stenosis affects 2 to 5 in 1,000 births. They also report that it usually affects infants under 6 months old and is less common in older children. Without treatment, pyloric stenosis can affect growth and development.

This article describes the causes and symptoms of pyloric stenosis, along with information about diagnosis and treatment.

Pyloric stenosis is a rare condition that occurs when the pylorus, a muscular valve at the bottom of the stomach, thickens. This causes the pylorus to shrink.

Typically, the pylorus opens and closes to allow food to pass through the small intestine during digestion. When pyloric stenosis develops, it cannot happen as it should. Foods and liquids cannot pass easily, so the body cannot digest and absorb them.

Although this condition can occur any time from birth, it usually develops in 2 to 8 weeks of age.

Babies with pyloric stenosis often have no symptoms at birth. When they develop, symptoms can include:

  • Projectile Vomit: Initially, a baby with pyloric stenosis may vomit a little, but as the pylorus thickens, the vomiting becomes forceful. This means that vomit can travel several feet across the room from the baby’s mouth.
  • Abdominal cramps: Before the baby vomits, a parent or caregiver may notice wave-like ripples in the baby’s upper abdomen immediately after eating. This is because the stomach muscles have to do more work than usual to push food through the small intestine.
  • Dehydration: Frequent vomiting can cause water loss, leading to dehydration. Dehydration can happen quickly in babies and can be fatal. A dehydrated baby may have few wet diapers, cry without tears, or become lethargic.
  • Constant hunger: A baby with a narrow pylorus may still be hungry, especially after vomiting, because he won’t keep milk or food down.
  • Constipation: Infants with pyloric stenosis may have difficulty emptying their bowels because a reasonable amount of food and water does not reach the small intestine.
  • Weightloss: Infants with pyloric stenosis may have difficulty gaining and maintaining weight.

A person should contact a doctor as soon as possible if a baby has any of the following signs and symptoms:

If the baby cannot keep food or water down or shows signs of dehydration, call 911 or the nearest emergency number. Signs of dehydration in infants include:

Health experts don’t know what causes pyloric stenosis, but have identified some risk factors that may increase the likelihood. These include:

  • Family history and genetics: Babies from families with a history of pyloric stenosis may have a higher risk of developing the condition. Research suggests that siblings have a 20 times higher risk of developing pyloric stenosis. In identical twins, the risk is multiplied by 200.
  • Sex: Male infants are Four times more likely to have pyloric stenosis than women.
  • Firstborns: Pyloric stenosis is more common in firstborn babies, which explains 30–40% of all cases. Scientists don’t know why.
  • Race: According to Centers for Disease Control and Prevention (CDC)Pyloric stenosis is more common in white infants and less common in non-Hispanic Asian and non-Hispanic Black infants.
  • Smoking: Smoking during pregnancy can double the risk of having a baby with pyloric stenosis.
  • Use of antibiotics: Ingesting certain types of antibiotics during their first 2 weeks of life can increase the risk of developing pyloric stenosis. This includes azithromycin and erythromycin by mouth.
  • Bottle-feeding: According to an older study from 2012, bottle-fed babies can be 4.6 times more likely to have pyloric stenosis than those who are not bottle fed. However, the researchers could not determine why this might be the case.

If an infant has signs or symptoms that may indicate pyloric stenosis, their caregiver should contact a pediatrician immediately. The pediatrician will perform a physical exam to check if an abdominal mass the size of an olive is present in the child’s upper abdomen.

They may also order other tests, including:

  • Blood tests: These can confirm dehydration or an electrolyte imbalance.
  • Abdominal ultrasound: This may show clear images of a thickened pyloric muscle.
  • An upper digestive series: For this test, a baby drinks a barium liquid before having a special stomach x-ray.

The gold standard treatment for pyloric stenosis is a surgical procedure known as Ramstedt pyloromyotomy. This widens the space inside the pylorus, allowing food and liquids to pass more easily.

Ramstedt pyloromyotomy procedure

Before surgery, a healthcare professional will test the baby’s blood to make sure they have healthy fluid and electrolyte levels. If they don’t, the baby will be given IV fluids.

Next, a healthcare professional will administer a general anesthetic so that the baby does not feel any pain. Then a pediatric surgeon will start the surgery.

Surgeons can perform a pyloromyotomy in two ways: laparoscopically, which is minimally invasive, and open surgery.

In a laparoscopic pyloromyotomy, the surgeon will make three small incisions and use a camera to see inside the abdomen. They then use small tools to cut the muscle around the pylorus. In an open pyloromyotomy, the surgeon makes a larger incision on the right side of the stomach and cuts the pylorus.

The surgery usually takes about 30 minutes.

After the operation

About 6 hours after surgery, the infant can start eating small amounts of food. These amounts can gradually increase as the baby tolerates it.

The baby will usually go home after 1-2 days in the hospital. Healthcare professionals will monitor the baby for any postoperative complications during this time.

Once they return home, they will need special care while they recover. That implies:

  • feeding as usual if breastfeeding or breastfeeding
  • feed the baby no more than 3 ounces of formula every 3 hours for the first 3 days after surgery, slowly increasing the amount after this time
  • take care of the incision wound, keep it clean and dry
  • avoid full baths for 2 days, give sponge baths instead
  • give the baby acetaminophen to reduce pain if the doctor says it’s okay

Without treatment, pyloric stenosis can lead to the following complications:

  • Hypovolemic shock: A late diagnosis can lead an emergency where the heart cannot pump enough blood to major organs due to severe dehydration.
  • Hematemesis: This is when a person vomits blood. Gastrointestinal irritation can upset the stomach lining, leading to mild bleeding in the stomach.
  • Jaundice: It is a buildup of bilirubin in the body, causing a yellowish discoloration of the eyes and skin. This may be due to low levels of hepatic glucuronosyl transferase in the blood.

Pyloric stenosis surgery also involves a few potential complications, such as infection. However, the benefits far outweigh the risks, and most babies recover quickly with no adverse results.

Speak to a doctor if a baby develops any of the following after surgery:

  • surgical wounds that are inflamed, swollen, bleeding, or leaking pus
  • a fever
  • continuous vomiting after most meals
  • a swollen belly

Here are answers to some common questions about pyloric stenosis.

Will pyloric stenosis go away on its own?

No, pyloric stenosis cannot get better on its own. It requires treatment by a doctor.

Can pyloric stenosis affect adults?

According to a 2018 report, pyloric stenosis occurs very rarely in adults. Sometimes it is idiopathic, which means the cause is unknown. At other times, it may appear alongside other medical conditions such as ulcers, gastrointestinal tumors or postoperative adhesions.

What is the long-term outlook for an infant with pyloric stenosis?

If left untreated, pyloric stenosis can lead to serious complications. However, the outlook for infants who receive surgery is generally good. Most make an excellent recovery and very few experience long-term problems due to illness.

Pyloric stenosis is a rare condition that usually affects infants under the age of 6 months. It occurs when the pylorus, the muscular valve at the bottom of the stomach, thickens.

Infants with pyloric stenosis may not appear sick at first, but as the pylorus narrows, it becomes more difficult for food and water to pass.

Symptoms of pyloric stenosis include projectile vomiting, stomach cramps, constipation, and dehydration. If anyone is concerned that a child may have pyloric stenosis, they should speak with a doctor immediately. A person with pyloric stenosis needs surgery to correct the condition and improve digestive function.


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