pyloric stenosis

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Related to Congenital Hypertropic Pyloric Stenosis: Duodenal atresia, Annular pancreas, Hirschsprung disease

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.

Key terms

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.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


pertaining to the pylorus or to the pyloric part of the stomach.
pyloric stenosis obstruction of the pyloric orifice of the stomach; it may be congenital, as in hypertrophic pyloric stenosis, or acquired, due to peptic ulceration or prepyloric carcinoma.

The initial symptom is vomiting, mild at first but becoming increasingly more forceful. It can occur both during and after feedings. Diagnosis may be confirmed by x-ray examination using a barium meal.

Treatment is usually surgical, involving longitudinal splitting of the muscle (pyloromyotomy).
Congenital pyloric stenosis. The abnormal narrowing of the opening of the pylorus causes episodes of projectile vomiting. From Frazier et al., 2000.


 [stĕ-no´sis] (pl. steno´ses)
an abnormal narrowing or contraction of a body passage or opening; called also arctation, coarctation, and stricture.
aortic stenosis obstruction to the outflow of blood from the left ventricle into the aorta; in the majority of adult cases the etiology is degenerative calcific disease of the valve.
hypertrophic subaortic stenosis (idiopathic hypertrophic subaortic stenosis) a cardiomyopathy of unknown cause, in which the left ventricle is hypertrophied and the cavity is small; it is marked by obstruction to left ventricular outflow.
mitral stenosis a narrowing of the left atrioventricular orifice (mitral valve) due to inflammation and scarring; the cause is almost always rheumatic heart disease. Normally the leaflets open with each pulsation of the heart, allowing blood to flow from the left atrium into the left ventricle, and close as the ventricle fills again so that they prevent a backward flow of blood. In mitral stenosis there is a resultant increase of pressure in the pulmonary artery and hypertrophy of the left ventricle. The usual treatment is surgical replacement of the valve.
pulmonary stenosis (PS) narrowing of the opening between the pulmonary artery and the right ventricle.
pyloric stenosis see pyloric stenosis.
renal artery stenosis narrowing of one or both renal arteries by atherosclerosis or by fibrous dysplasia or hyperplasia, so that renal function is impaired (see ischemic nephropathy). Increased renin release by the affected kidney causes renovascular hypertension, and bilateral stenosis may result in chronic renal failure.
spinal stenosis narrowing of the vertebral canal, nerve root canals, or intervertebral foramina of the lumbar spine, caused by encroachment of bone upon the space; symptoms are caused by compression of the cauda equina and include pain, paresthesias, and neurogenic claudication. The condition may be either congenital or due to spinal degeneration.
subaortic stenosis aortic stenosis due to an obstructive lesion in the left ventricle below the aortic valve, causing a pressure gradient across the obstruction within the ventricle. See also idiopathic hypertrophic subaortic stenosis.
subglottic stenosis stenosis of the trachea below the glottis. A congenital form results in neonatal stridor or laryngotracheitis, often requiring tracheotomy but resolving with age. An acquired form is caused by repeated intubations.
tracheal stenosis scarring of the trachea with narrowing, usually as a result of injury from an artificial airway or trauma.
tricuspid stenosis (TS) narrowing or stricture of the tricuspid orifice of the heart, a condition often seen in patients with severe congestive heart failure, usually the result of volume overload and pulmonary hypertension with right ventricular and tricuspid annular dilation.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

py·lor·ic ste·no·sis

narrowing of the gastric pylorus, especially by congenital muscular hypertrophy or scarring resulting from a peptic ulcer.
See also: hypertrophic pyloric stenosis.
Farlex Partner Medical Dictionary © Farlex 2012

pyloric stenosis

Congenital hypertrophic pyloric stenosis, hypertrophic pyloric stenosis GI disease A narrowing of the gastric outlet into the duodenum due to thickening of pyloric muscle, which controls gastric flow to the duodenum; PS is more common in ♂; Sx appear shortly after birth.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

py·lor·ic ste·no·sis

(pī-lōr'ik stĕ-nō'sis)
Narrowing of the gastric pylorus, especially by congenital muscular hypertrophy or scarring resulting from a peptic ulcer.
See also: hypertrophic pyloric stenosis
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

pyloric stenosis

Narrowing of the muscular outlet from the stomach (the pylorus) so that the passage of food into the DUODENUM is obstructed. The condition may be CONGENITAL, calling for an urgent operation to relieve the obstruction, or may be acquired as a result of repeated attacks of ulceration in the area. In this case, PYLOROPLASTY may be needed. Pyloric stenosis is occasionally caused by cancer of the stomach.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
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