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Pyloric Stenosis

Pyloric Stenosis


Pyloric stenosis refers to a narrowing of the passage between the stomach and the small intestine. The condition, which affects infants during the first several weeks of life, can be corrected effectively with surgery.


Frequent vomiting may be an indication of pyloric stenosis. The pylorus is the passage between the stomach and the small intestine. During the digestive process food passes through the pylorus, which is located near the bottom of the stomach, on its way to the intestines. In pyloric stenosis, the muscular wall of the passage becomes abnormally thickened. This causes the pylorus to become too narrow, which prevents food from emptying out of the stomach in a normal fashion. The partially digested contents of the stomach are forced upwards into the mouth. As a result, a baby with pyloric stenosis often vomits after feedings.

The condition affects one in 4,000 infants. Most are diagnosed between three and five weeks old, though some babies may show symptoms during the first or second week of life. Infants with a family history of pyloric stenosis are more at risk for the condition, which tends to occur less often in females, blacks, and Asians. Pyloric stenosis is also referred to as hypertrophic pyloric stenosis.

Causes and symptoms

The cause of pyloric stenosis is not known. The main symptom is vomiting after feedings. These episodes of vomiting usually get worse over time, happening more often and becoming more forceful (forceful vomiting is often called "projectile" vomiting). Other symptoms include increased appetite, weight loss, infrequent bowel movements, belching, and diarrhea. Due to dehydration, the infant may also have fewer wet diapers.


The clinician will examine the baby and talk with the parents about their infant's symptoms. If a child has the condition, the doctor should be able to feel a hard mass (about 2 cm wide and olive shaped) in the area above the bellybutton. If the doctor cannot detect the mass, ultrasonography will be done to confirm the diagnosis. A blood test may also be performed to see if the infant is dehydrated, in which case intravenous fluids can be used to correct the problem.


Pyloric stenosis can be cured with a surgical procedure called a pyloromyotomy. In this operation, the surgeon makes an incision in the baby's abdomen. Then a small cut is made in the thickened muscle of the pylorus and it is spread apart. In this manner, the passage can be widened without removing any tissue. (The procedure may be performed with the aid of a laparoscope.) After surgery, the pylorus will heal itself. The thickening gradually goes away and the passage resumes a normal shape. The whole procedure (including anesthesia) takes about an hour.

Most babies go home one or two days after surgery. Any mild discomfort can be controlled with Tylenol. The infant may still vomit occasionally after surgery, but this is not usually a cause for alarm. However, if vomiting occurs three or more times a day, or for several consecutive days, the baby's pediatrician should be notified.

Alternative treatment

None known.


Surgery is often a complete cure. Most infants do not experience complications or long-term effects.


It is not known how to prevent pyloric stenosis.



Behrman, Richard E., et al., Nelson Textbook of Pediatrics. Philadelphia: WB Saunders, 2000.


Yoshizawa J, et al. Ultrasonographic Features of Normalizationof the Pylorus after Pyloromyotomy for Hypertrophic Pyloric Stenosis. "Journal of PediatricSurgery" 36 (April 2001): 582-6.


American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 906-6000.

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007-1098. (847) 434-4000.


Laparoscope A thin, camera-fitted tube that can be inserted into the abdomen in order to view internal organs.

Stenosis The narrowing of a passage (such as the pylorus).

Ultrasonography A non-invasive imaging procedure that uses high-frequency sound waves.

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"Pyloric Stenosis." Gale Encyclopedia of Medicine, 3rd ed.. . 12 Dec. 2017 <>.

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"Pyloric Stenosis." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved December 12, 2017 from

pyloric stenosis

pyloric stenosis (py-lor-ik) n. narrowing of the pylorus. This causes delay in passage of the stomach contents to the duodenum, which leads to repeated vomiting. Pyloric stenosis in adults is caused by a peptic ulcer close to the pylorus or by a cancerous growth invading it. congenital hypertrophic p. s. pyloric stenosis that occurs in babies about 3–5 weeks old (particularly boys) in which the thickened pyloric muscle can be felt as a nodule. Treatment is by pyloromyotomy.

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"pyloric stenosis." A Dictionary of Nursing. . 12 Dec. 2017 <>.

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