Pyloric stenosis Dr Rob Hicks About one in 4,000 babies develops pyloric stenosis.

In this article

What is pyloric stenosis? Symptoms

Causes and risk factors Treatment and recovery

Pyloric stenosis is a narrowing of the outlet of the stomach, called the pylorus, as it empties into the small intestines.

One of the main symptoms is vomiting. This may be mild at first but progressively becomes more forceful until it is projectile (spurts a long distance out from the baby). The vomiting becomes more frequent until it occurs after every feed.

There's constant hunger, even after vomiting, but the baby fails to grow and often loses weight.

There may be loose greenish diarrhoea and eventually dehydration results.

The narrowing of the pylorus results from a thickening or hypertrophy of the muscle wall, but the cause of pyloric stenosis isn't yet clear.

Genetic factors play a part. There's often a family history of the condition, especially on the mother's side of the family.

It almost always affects very young babies, usually appearing between two and seven weeks of age and very rarely after six months.

Boys are affected four times more often than girls, and it's especially common among first-born boys.

A feed test is usually performed to establish the diagnosis. The baby is given a milk feed and a wave of movement may be seen moving from left to right across the abdomen as the stomach tries to empty through the obstruction.

The pylorus may be felt as a hard lump the shape and size of an olive, between the right side of the ribcage and the umbilicus. An ultrasound scan is done to confirm the diagnosis.

Treatment consists of rehydration followed by an operation to cut or split the overdeveloped muscle of the pylorus (called a pyloromyotomy). This may be done as keyhole surgery, through an endoscope (a telescope-like tube).

Most children recover rapidly after surgery and are soon able to take normal feeds.

This article was last medically reviewed by Dr Orlena Kerek in March 2009