Normally, food passes easily from the stomach into the first part of the small intestine through a valve called the pylorus. In pyloric stenosis, the muscles of the pylorus are thickened. This prevents the stomach from emptying into the small intestine.
The cause of the thickening is unknown, although genetic factors may play a role. Children of parents who had pyloric stenosis are more likely to have this condition.
Pyloric stenosis occurs more often in boys than in girls, and is rare in children older than 6 months. The condition is usually diagnosed by the time a child is 6 months old.
Vomiting is the first symptom in most children:
Vomiting may occur after every feeding or only after some feedings
Vomiting usually starts around 3 weeks of age, but may start any time between 1 week and 5 months of age
Vomiting is forceful (projectile vomiting)
The infant is hungry after vomiting and wants to feed again
Other symptoms generally appear several weeks after birth and may include:
Dehydration (gets worse with the severity of the vomiting)
Failure to gain weight or weight loss
Wave-like motion of the abdomen shortly after feeding and just before vomiting occurs
Signs and tests
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. The doctor may detect the abnormal pylorus, which feels like an olive-shaped mass, when touching the stomach area.
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.
Complications of pyloric stenosis include:
Failure for the baby to gain weight
Calling your health care provider
Call your health care provider if your baby has symptoms of this condition.
Hunter AK, Liacouras CA. Pyloric stenosis and congenital anomalies of the stomach. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th Ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 321.
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.