Pyloric stenosis

What is pyloric stenosis?

pyloric stenosis

The outlet of the stomach into the small intestine is called the pylorus. Stenosis means a narrowing. Pyloric stenosis means a narrowed outlet of the stomach.

Food and drink pass down the gullet (oesophagus) into the stomach. Here the food and drink mixes with acid and are partially digested. The stomach then normally passes the food and drink into the small intestine to be fully digested and absorbed into the body.

When the outlet from the stomach into the small intestine is narrowed this causes a serious illness unless it is treated.

Symptoms typically begin in a baby aged between 2 and 6 weeks who is otherwise healthy.

Vomiting after a feed is the main symptom. The vomiting may start like a 'normal' vomit but often the vomiting is forceful and milk may be vomited quite a distance like a fountain. This is called projectile vomiting.

The baby remains alert and hungry, and will usually feed well - only to vomit the milk back soon after feeding. The vomiting tends to become worse and worse over several days.

Little food or drink passes through the narrowed pylorus which becomes narrower over time. This means that little or no food reaches the bowels, so babies often pass very little faeces (poo). Affected babies do not gain weight, and are in danger of quickly becoming dehydrated and seriously ill if the condition is not treated.

Notera: it is very common for newborn babies to vomit. The vast majority of babies who vomit do inte have pyloric stenosis.

The muscle in the wall of the outlet of the stomach into the small intestine (pylorus) is abnormally thick. This causes the outlet from the stomach to become narrowed (stenosed). It is not known why this occurs though some risk factors have been identified. Use of a particular type of antibiotic shortly after birth has been shown to be a risk factor for developing pyloric stenosis.

Pyloric stenosis affects between 2 and 5 out of 1,000 babies. Boys are affected more commonly than girls. It can sometimes run in families. It is more common in babies who are bottle fed, who were born by caesarean section or who were born prematurely. It is more common in first-born babies. It is also more common in babies born to women who smoked during pregnancy.

It is seen most commonly in white babies and less frequently in Black or Asian babies.

Often the story is enough to make a doctor suspect the diagnosis of pyloric stenosis. A doctor may examine the baby's abdomen whilst they are feeding. A typical bulge next to the stomach can sometimes be felt as the muscles in the stomach and stomach outlet (pylorus) contract.

An ultrasound scan may be done if there is doubt about the diagnosis. This painless test is very reliable at detecting the thickened pylorus. Possibly because ultrasound is being used more frequently, pyloric stenosis is being diagnosed earlier and fewer babies are becoming very unwell before being diagnosed.

A small operation, done under a general anaesthetic, normally cures the problem. A small cut is made in the skin over the stomach outlet (pylorus) and the pylorus itself is then cut to create a channel for food to pass through. This operation is called a pyloromyotomy.

Food and milk can then pass easily out of the stomach into the bowel.

A pyloromyotomy is now usually done by keyhole surgery. This uses only a tiny cut to the skin to allow fine instruments into the abdomen to cut the pylorus muscle.

The operation is usually totally successful. Normal feeds are started again shortly after the operation. Most babies recover quickly and have no further problems.

Pyloric stenosis cannot be prevented. Although there are certain risk factors which might make it more likely, there is always a combination of factors causing pyloric stenosis so it cannot be prevented.