Pediatric Surgical Services
Hasbro Children's Hospital

Pyloric Stenosis

What is pyloric stenosis?

Pyloric stenosis is a condition specific to young infants, usually between two and five weeks of age, who have been otherwise healthy and feeding well for the first weeks of life. It presents as severe vomiting, usually after feeding. As the condition worsens, vomiting occurs after every feeding, and the baby is at risk of dehydration and malnutrition. Although babies may vomit for many different reasons, what makes pyloric stenosis so typical is the fact that the baby is otherwise not sick and is extremely hungry right after having vomited.

Normally, the contents of the stomach (food, fluids, formula or the stomach's own secretions) do not empty rapidly into the next portion of the intestinal tract (duodenum and small bowel). A sphincter-like muscle at the junction between stomach and duodenum only allows stomach contents to empty intermittently, and in small portions at a time. It does this by alternatively opening and closing. In pyloric stenosis, the pyloric muscle remains contracted, and does not open at all. Therefore, the contents of the stomach never empty into the intestines. If the stomach's efforts to 'squeeze' its contents past the closed pylorus are unsuccessful, these forceful contractions of the stomach will cause the child to vomit the undigested formula, often under considerable force (projectile vomiting).

The exact cause of pyloric stenosis is unknown. It is more common in boys, often the first-born child, and it tends to run in families. However, nobody knows why it occurs or why it is not present at birth but rather a few weeks later. Children who have had pyloric stenosis are not at increased risk of developing stomach, intestinal or other diseases later in life.

Why does pyloric stenosis require surgery?

If left untreated, pyloric stenosis will eventually prevent the baby from taking in any fluids or formula. Therefore, he or she rapidly may become severely dehydrated and eventually malnourished. In addition, the frequent vomiting of stomach contents may cause severe imbalances in the composition of the baby's blood and body fluids. There is no good non-operative treatment for pyloric stenosis.

We now know that after the operation, the baby's pylorus will eventually heal to become a normal, circumferential sphincter muscle. This occurs within two to three weeks of the operation. However, the baby is cured immediately and can tolerate feedings within hours of the operation.

What needs to be done before surgery?

The most immediate dangers to your baby are dehydration and electrolyte (body fluids) imbalance. Malnutrition is not an immediate problem, and neither is the hypertrophy (exaggerated spasm) of the pyloric muscle. The pyloric stenosis itself is not causing any pain or discomfort to your baby, other than hunger and frustration.

Therefore, your baby needs to be hydrated first (with an intravenous fluid solution, since he or she can't keep anything down). At the same time, we need to make sure that the electrolytes in his or her blood are not abnormally low. If they are, we need to correct the imbalance first, before your baby can undergo general anesthesia and surgery.

Once your baby is stable and well hydrated, we can proceed with the operation. The procedure, which has not changed much over the last several decades, is called pyloromyotomy.

What happens during and after surgery?

The operation itself lasts about 30 minutes and is done under general anesthesia. At the end of the operation, your baby will be transported to the recovery room. Once everything is settled, someone will bring you to your child so that you can be there as he wakes up. Once your baby is fully awake and recovered, he will be transferred to his room. Feeding, first with water or a flavored electrolyte solution, can be started six hours after the operation. Once your baby is tolerating a normal feeding schedule, you will be allowed to go home.

Not uncommonly, your baby will still vomit once in a while, although not as severely as before. In part, this is because the stomach still tries to forcefully squeeze its contents past a pylorus that, hours before, was still tightly closed. It is also possible that your child has reflux, a condition which, in its mild form, is almost always present in infants for the first few months of life.