Pyloric stenosis is a narrowing of the pylorus, the opening from the stomach into the small intestine.

Pyloric stenosis is caused by a thickening of the muscles of the pylorus. This thickening prevents the stomach from emptying into the small intestine.

The cause of the thickening is unknown, although genetic factors may play a role. Pyloric stenosis occurs more commonly in boys than in girls, and is rare in patients older than 6 months. The condition is usually diagnosed by the time a child is 6 months old.

Symptoms generally appear several weeks after birth:

• Abdominal fullness prematurely after meals
• Abdominal pain
• Belching
• Constant hunger
• Dehydration (gets worse with the severity of the vomiting and diarrhea)
• Diarrhea (loose, watery stools)
• Failure to gain weight or weight loss
• Wave-like motion of the abdomen shortly after feeding and just before vomiting occurs
• Vomiting
  • Persistant vomiting after every feeding
  • Projectile vomiting

The condition is usually diagnosed before the baby is 6 months old.

A physical exam may reveal signs of dehydration. The infant may have a swollen belly area. The doctor may detect the abnormal pylorus, which feels like an olive-shaped mass, when touching the stomach area.

An ultrasound of the abdomen may be the first imaging test performed. Other tests that may be done include:

• Blood chemistry panel -- often reveals an electrolyte imbalance
• Barium x-ray -- reveals a swollen stomach and narrowed pylorus

Treatment for pyloric stenosis involves surgery (called a pyloromyotomy) to split the overdeveloped muscles.

Balloon dilation does not work as well as surgery, but may be considered for infants when the risk of general anesthesia is high.

The patient will be given fluids through a vein, usually before surgery.

Surgery usually provides complete relief of symptoms. The infant can usually tolerate small, frequent feedings several hours after surgery.

• Vomiting after surgery -- this is very common and generally improves with time
• Failure to gain weight in the newborn period
• Risks associated with any surgery, which include:
  • Bleeding
  • Infection

Call your health care provider if your baby has symptoms of this condition.