Health Encyclopedia

Pyloric stenosis

Definition

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

Alternative Names

Congenital hypertrophic pyloric stenosis; Hypertrophic pyloric stenosis; Gastric outlet obstruction

Causes, incidence, and risk factors

Normally, food passes easily from the stomach into the duodenum (the first part of the small intestine) through a valve called the pylorus. In pyloric stenosis, the muscles of the pylorus are thickened. 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. Children of parents who had pyloric stenosis are more likely to have this problem.

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.

Symptoms

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:

Abdominal pain
Belching
Constant hunger
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.

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

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

Treatment

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.

Expectations (prognosis)

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

Complications

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

Calling your health care provider

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

References

Wyllie R. Pyloric stenosis and congenital anomalies of the stomach. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th Ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 326.

Review Date:8/2/2009
Reviewed By: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.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.