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Pyloric stenosis

Last reviewed: 30 Oct 2023
Last updated: 28 Sep 2022



History and exam

Key diagnostic factors

  • first-born male infant
  • nonbilious projectile vomiting
  • 3 to 6 weeks old
  • upper abdominal mass
  • peristaltic waves
More key diagnostic factors

Other diagnostic factors

  • family history of pyloric stenosis
  • multiple formula changes
  • tachycardia
  • decreased wet diapers
  • dry mucous membranes
  • flat or depressed fontanelles
  • constipation
  • poor weight gain
  • irritability
Other diagnostic factors

Risk factors

  • prematurity
  • early exposure to erythromycin
  • exposure to prostaglandins
  • maternal exposure to macrolides
  • geographic location/ethnic background
  • first-born male infant
  • family history of pyloric stenosis
More risk factors

Diagnostic investigations

1st investigations to order

  • chemistry panel
  • ultrasound abdomen
More 1st investigations to order

Treatment algorithm


all patients



Catherine J. Hunter, MD

Professor of Surgery and Division Chief of Pediatric Surgery

Oklahoma Children’s Hospital

The University of Oklahoma College of Medicine

Oklahoma City



CJH declares that she has no competing interests.


Dr Catherine Hunter would like to gratefully acknowledge Dr Samuel C. Klonoski, Dr Jeffrey S. Upperman, Dr Yigit S. Guner, and Dr Arturo Aranda, previous contributors to this topic. SCK, JSU, YSG, and AA declare that they have no competing interests.

Peer reviewers

Evan Nadler, MD

Assistant Professor of Surgery

Department of Surgery

Division of Pediatric Surgery

NYU Medical Center

New York



EN declares that he has no competing interests.

Lewis Spitz, PhD FRCS MD (Hon), FRCPCH FAAP (Hon), FCS (SA) (Hon)

Emeritus Nuffield Professor of Paediatric Surgery

Institute of Child Health

University College




LS declares that he has no competing interests.

Ruth Hallows, BSc, MB BS, FRCS, FRCS III (Paediatric Surgery)

Consultant in Paediatric and Neonatal Surgery

Royal Alexandra Children's Hospital




RH declares that she has no competing interests.

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