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Pyloric stenosis

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

Alternative Names

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

Causes

Normally, food passes easily from the stomach into the first part of the small intestine through a valve called the pylorus. With 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. Genes may play a role, since children of parents who had pyloric stenosis are more likely to have this condition.

Pyloric stenosis occurs most often in infants younger than 6 months. It is more common in boys than in girls.

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 appear several weeks after birth and may include:

  • Abdominal pain
  • Burping
  • Constant hunger
  • Dehydration (gets worse as vomiting gets worse)
  • Failure to gain weight or weight loss
  • Wave-like motion of the abdomen shortly after feeding and just before vomiting occurs

Exams and Tests

The condition is usually diagnosed before the baby is 6 months old.

A physical exam may reveal:

  • Signs of dehydration, such as dry skin and mouth, less tearing when crying, and dry diapers
  • Swollen belly
  • Olive-shaped mass when feeling the upper belly, which is the abnormal pylorus

Ultrasound of the abdomen may be the first imaging test. Other tests that may be done include:

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

Treatment

Treatment for pyloric stenosis involves surgery to widen the pylorus. The surgery is called pyloromyotomy.

If putting the infant to sleep for surgery is not safe, a device called an endoscope with a tiny balloon at the end is used. The balloon is inflated to widen the pylorus.

In infants who cannot have surgery, tube feeding or medicine to relax the pylorus is tried.

Outlook (Prognosis)

Surgery usually relieves all symptoms. As soon as several hours after surgery, the infant can start small, frequent feedings.

When to Contact a Medical Professional

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

References

Hunter AK, Liacouras CA. Pyloric stenosis and congenital anomalies of the stomach. In: Kliegman RM, Stanton BF, St. Geme JW III, et al., eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Elsevier Saunders; 2011: chap 321.

Pandya S, Heiss K. Pyloric stenosis in pediatric surgery. Surg Clin N Am. 2012;92:527-553.

Updated: 8/22/2013

Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.


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