Pyloric Stenosis
Basics
Description
Acquired narrowing of the pyloric canal due to progressive hypertrophy of pyloric muscle leading to obstruction
Epidemiology
- Presentation is most common between 2 and 8 weeks of age, with a median presentation of 6 weeks
- The most common condition requiring surgical intervention in the 1st year of life
Incidence
- Highest incidence found in first-born males
- Overall 1.56 per 1,000 live births
- Higher in Caucasian and Hispanic children
Etiology and Pathophysiology
- Impaired physiologic relaxation of the pyloric muscle leads to hypertrophy.
- Gastric outflow is obstructed, leading to gastric distension and forceful projectile postprandial vomiting.
Risk Factors
- Maternal smoking during pregnancy
- C-section delivery
- Prematurity
- Formula feeding which may cause higher serum levels associated with pylorospasm
- Postnatal macrolide antibiotics, especially if administered in the first 2 weeks of life
- Multiple gestations:
- 200-fold increased risk if monozygotic twin affected
- 20-fold increased risk if dizygotic twin affected
General Prevention
Breast milk contains increased vasoactive intestinal peptides which are agents of smooth muscle relaxation.
Commonly Associated Conditions
Hiatal and inguinal hernias
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Citation
Domino, Frank J., et al., editors. "Pyloric Stenosis." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116508/all/Pyloric_Stenosis.
Pyloric Stenosis. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116508/all/Pyloric_Stenosis. Accessed December 12, 2024.
Pyloric Stenosis. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116508/all/Pyloric_Stenosis
Pyloric Stenosis [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 December 12]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116508/all/Pyloric_Stenosis.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Pyloric Stenosis
ID - 116508
ED - Domino,Frank J,
ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116508/all/Pyloric_Stenosis
PB - Wolters Kluwer
ET - 33
DB - Medicine Central
DP - Unbound Medicine
ER -