Family History Increases the Risk of Hypertrophic Pyloric Stenosis in Infants

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What is Pyloric Stenosis?

Pyloric stenosis or hypertropic pyloric stenosis is a common disease in infants under the age of one year. It is a narrowing of the pylorus or lowest part of the stomach that leads to the small intestines. This area can become constricted or blocked off if the sphincter muscle around the opening of the pylorus has grown abnormally large.

Though the cause of pyloric stenosis is unclear, a family history of this disease in which a parent or sibling suffered from it is important because it increases the risk by up to five times. Ethnicity is also important as this disease is more prevalent in Caucasians than in Hispanic, Asian Indian, Chinese, or Black infants. Pyloric stenosis is also more common in boys. According to a medical study, young maternal age (less than 20 years) was associated with a 29% increased risk of pyloric stenosis while a maternal (mother’s) age of 30 years or older showed decreased risk.


Most infants with pyloric stenosis begin to vomit during the second to third week of life. This begins with spitting up and then turns into forceful projectile vomiting as milk or formula cannot pass the narrowed pylorus and begins collecting in the stomach. The infant may refuse to feed and may be in discomfort. The vomiting is chronic, does not contain bile, becomes progressively worse and occurs after the baby is fed. Other symptoms include dehydration, weight loss, malaise and sleepiness as the baby becomes malnourished. The infant may also have a sunken soft spot at the top of the head. As food does not get passed to the intestines, the baby will also not urinate or defecate.


A physical exam by a pediatrician or family doctor may show an enlarged pyloric valve. It is often difficult to detect as the stomach may be full of milk or air and a nasogastric tube, placed through the infant’s nose or mouth is first used to drain the stomach.

An abdominal ultrasound is used to confirm a diagnosis, as is an x-ray using barium. In this test, the infant fed a small amount of barium which shows up clearly on an x-ray as it reached the pyloric stenosis. These tests help to prevent misdiagnosis.

Treating Pyloric Stenosis and Dehydration

If an infant is diagnosed with pyloric stenosis, blood tests will determine if there is dehydration and a vein catheter will be used to immediately replace vital fluids. Surgery is required to correct the stenosis. This procedure, called a pyloromyotomy, opens the muscles around the pyloric part of the stomach and reattaches it with dissolvable stitches. Most infants are discharged from the hospital two days after surgery but feedings may take a few days to become normal and must be started slowly.