Infantile hypertrophic pyloric stenosis
Infantile hypertrophic pyloric stenosis
Erin E Endom, MD
Scott R Dorfman, MD
Anthony P Olivé, MD
Section Editors:
Joshua Nagler, MD, MHPEd
Deputy Editor:
Alison G Hoppin, MD
Literature review current through: Mar 2024.
This topic last updated: Jan 27, 2023.


Infantile hypertrophic pyloric stenosis (IHPS) is a disorder of young infants caused by hypertrophy of the pylorus, which can progress to near-complete obstruction of the gastric outlet, leading to forceful vomiting.

The clinical manifestations, diagnosis, and treatment of IHPS are discussed below. The differential diagnosis of vomiting in infants and other related content are discussed separately. (See "Approach to the infant or child with nausea and vomiting" and "Anesthesia for pyloromyotomy in infants".)


IHPS usually develops between three and five weeks of age and very rarely occurs after 12 weeks of age [1]. A trend toward earlier diagnosis was illustrated in a study comparing the presentation of a total of 283 infants diagnosed in the decades prior to 1975, 1985, and 1995 [2]. The mean age at presentation was significantly younger in the more recent decades (mean age 5.4 weeks in 1975 versus 3.4 weeks in 1995) [3]. The earlier diagnosis of IHPS might be explained by advances in diagnostic imaging or by increased awareness of the disorder among clinicians.

The condition occurs in approximately 1 to 3.5 per 1000 live births, although rates and trends vary markedly from region to region [4-10]. Several reports from resource-abundant countries suggest a declining incidence, with variable rates [5,8,9,11].

The incidence of IHPS is associated with:

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