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Hypertrophic pyloric stenosis

Last updated: June 14, 2020

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Hypertrophic pyloric stenosis – the most common cause of gastric outlet obstruction in infants – is characterized by hypertrophy and hyperplasia of the pyloric sphincter in the first months of life. Clinical manifestations usually appear between three and five weeks of age. The primary symptom is regurgitation progressing to nonbilious, projectile vomiting, which occurs intermittently or after feeding. The infant is irritable and demonstrates a strong rooting and sucking reflex because of hunger. Constant vomiting leads to hypokalemic and hypochloremic metabolic alkalosis. The diagnosis is usually clinical and involves the detection of a palpable "olive-shaped" structure in the epigastrium (a sign of marked hypertrophy of the pylorus) and visible gastric peristalsis proximal to the site of obstruction. The condition may also be diagnosed on ultrasound in the absence of a palpable “olive-shaped” structure. Initial management involves adequate rehydration and correction of electrolyte imbalances. The definitive treatment is Ramstedt pyloromyotomy.


Epidemiological data refers to the US, unless otherwise specified.


  • Symptoms usually develop between the 2nd and 7th week of age (rarely after the 12th week).
  • Frequent regurgitation progressing to projectile, nonbilious vomiting immediately after feeding
  • An enlarged, thickened, "olive-shaped”, non-tender pylorus (diameter of 1–2 cm) should be palpable in the epigastrium
  • A peristaltic wave, moving from left to right, may be evident in the epigastrium
  • "Hungry vomiter": demands re-feeding after vomiting; , demonstrates a strong rooting and sucking reflex, irritable
  • If left untreated: dehydration, weight loss, failure to thrive


Nowadays, hypertrophic pyloric stenosis is diagnosed early, and infants generally do not present with significant electrolyte imbalances.


Differential diagnosis of newborn vomiting
Condition Findings
Hypertrophic pyloric stenosis
Midgut volvulus and intestinal malrotation
Benign gastroesophageal reflux
  • Regurgitation and/or vomiting of food shortly after feeding
  • Healthy children with normal development
Gastroesophageal reflux disease
  • Regurgitation and/or vomiting of food shortly after feeding
  • Poor appetite, weight loss, failure to thrive
  • Abdominal pain/discomfort
  • Wheezing, stridor, chronic cough, hoarseness
Congenital adrenal hyperplasia with salt loss
Cyclical vomiting syndrome [7]
  • ≥ 3 episodes of acute vomiting in the past year; each episode lasting < 1 week; asymptomatic intervals between episodes.

Benign gastroesophageal reflux (GER)

  • Etiology: temporary insufficiency of the lower esophageal sphincter
  • Clinical features
    • Regurgitation and/or vomiting of food shortly after feeds
    • Overall healthy appearance, normal development, no weight loss
  • Diagnostics: clinical diagnosis
  • Treatment
    • Positioning therapy: maintain upright position after feeding, avoid sitting or supine position
    • Thickening of food
  • Prognosis: very good; resolves spontaneously in the majority of cases by approx. 18 months of age

Gastroesophageal reflux disease (GERD)

  • Definition: GER associated with persistent symptoms and complications
  • Etiology: persistent insufficiency of the lower esophageal sphincter
  • Clinical features
    • Regurgitation, vomiting
    • Poor appetite, refusal to feed, weight loss, failure to thrive
    • Abdominal pain/discomfort
    • Crying and irritability
    • Wheezing, stridor, hoarseness, chronic cough
  • Diagnostics: mainly a clinical diagnosis; imaging can be indicated if symptoms after initiation of empirical treatment persist
  • Treatment
    1. Conservative measures: positioning therapy and thickening of food (see “Treatment” section of GER above)
    2. Pharmacological treatment: H2-receptor blockers (e.g., ranitidine) and PPIs

Cyclical vomiting syndrome

  • Etiology: unknown; a family history with migraines is common
  • Epidemiology: peak incidence in children 3–7 years of age
  • Presentation
    • Recurrent attacks of severe vomiting; (bilious or non-bilious) with a typical pattern and no evidence of anatomical anomalies
    • Attacks can be accompanied by severe nausea, headaches, photophobia, abdominal pain
  • Diagnostic criteria (Rome III criteria for cyclical vomiting syndrome): All three criteria need to be fulfilled for the diagnosis of cyclical vomiting syndrome to be made [7][8]
    • ≥ 3 episodes of acute vomiting in the past year
    • Each episode lasting < 1 week
    • Asymptomatic intervals between episodes
  • Treatment
    • Avoid possible triggers (e.g., foods such as cheese or chocolate; stress)
    • Prophylactic treatment
    • Supportive care (e.g., IV fluids)

Sandifer syndrome


The differential diagnoses listed here are not exhaustive.

  • Conservative measures: before surgery
    • Correct electrolyte imbalance (e.g., replace K+)
    • IV rehydration
    • Frequent administration of small meals (12–24 per day)
    • Elevate head
  • Treatment of choice: Ramstedt pyloromyotomy (a longitudinal muscle-splitting incision of the hypertrophic sphincter)



  1. Rosenthal YS et al.. The incidence of infantile hypertrophic pyloric stenosis and its association with folic acid supplementation during pregnancy: A nested case–control study. J Pediatr Surg. 2019; 54 (4): p.701-706. doi: 10.1016/j.jpedsurg.2018.05.005 . | Open in Read by QxMD
  2. Subramaniam S. Pediatric Pyloric Stenosis. In: Bechtel KA, Pediatric Pyloric Stenosis. New York, NY: WebMD. http://emedicine.medscape.com/article/803489. Updated: November 20, 2016. Accessed: December 30, 2016.
  3. Krogh C, Gørtz S, Wohlfahrt J et al.. Pre- and perinatal risk factors for pyloric stenosis and their influence on the male predominance. American Journal of Epidemiology. 2012; 176 (1): p.24-31. doi: 10.1093/aje/kwr493 . | Open in Read by QxMD
  4. Krogh C, Biggar RJ, Fischer TK et al.. Bottle-feeding and the Risk of Pyloric Stenosis. Pediatrics. 2012; 130 (4). doi: 10.1542/peds.2011-2785 . | Open in Read by QxMD
  5. Olivé AP, Endom EE. Infantile hypertrophic pyloric stenosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/infantile-hypertrophic-pyloric-stenosis.Last updated: October 19, 2016. Accessed: December 30, 2016.
  6. Emmett M, Szerlip H. Causes of metabolic alkalosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/causes-of-metabolic-alkalosis.Last updated: October 9, 2015. Accessed: December 30, 2016.
  7. Abell TL, Adams KA, Boles RG, et al. Cyclic vomiting syndrome in adults. Neurogastroenterology & Motility. 2008; 20 (4): p.269-284. doi: 10.1111/j.1365-2982.2008.01113.x . | Open in Read by QxMD
  8. Venkatesan T. Cyclic Vomiting Syndrome. In: Cuffari C, Cyclic Vomiting Syndrome. New York, NY: WebMD. http://emedicine.medscape.com/article/933135. Updated: March 9, 2016. Accessed: December 30, 2016.
  9. Desilets DJ. Cyclic vomiting syndrome. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/cyclic-vomiting-syndrome.Last updated: May 17, 2016. Accessed: December 30, 2016.
  10. Sandifer syndrome. https://rarediseases.info.nih.gov/diseases/9684/sandifer-syndrome. Updated: March 1, 2007. Accessed: May 12, 2020.
  11. Hernanz-schulman M. Infantile hypertrophic pyloric stenosis. Radiology. 2003; 227 (2): p.319-31. doi: 10.1148/radiol.2272011329 . | Open in Read by QxMD