Pyloric stenosis
Other names Infantile hypertrophic pyloric stenosis, IPHS
Anesthetic relevance


Anesthetic management
  • Delay surgery to correct electrolyte abnormalities and hypovolemia
  • Decompress stomach prior to induction
  • Modified RSI

Pediatric surgery

Signs and symptoms

Projectile vomiting




Fluid resuscitation Correction of electrolytes Surgery

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Pyloric stenosis (also called infantile hypertrophic pyloric stenosis, IHPS) is a disorder of early infancy caused by hypertrophy of the pylorus which leads to a narrowing of the opening from the stomach to the first part of the small intestine. This can cause an obstruction of the gastric outlet, leading to projectile vomiting without the presence of bile.

Anesthetic implications

Preoperative optimization

  • Delay surgery for fluid resuscitation and electrolyte correction
    • Procedure is urgent but not emergent
  • Recommended preoperative thresholds include:[1]
    • pH ≤7.45 (base excess ≤3.5)
    • Bicarbonate <26 mmol/L
    • Sodium ≥132 mmol/L
    • Potassium ≥3.5 mmol/L
    • Chloride ≥100 mmol/L
    • Glucose ≥4.0 mmol/L (72 mg/dL)

Intraoperative management

  • Decompress stomach via OG or NG prior to induction[2]
    • Supine, left lateral decubitus, and right lateral decubitus positions
  • Modified RSI IV induction[3]
    • No increased risk of aspiration compared to traditional RSI
    • Traditional RSI leads to more hypoxia
  • Extubate awake

Postoperative management

  • Feeding can resume within hours after surgery[4]
    • Modest regurgitation is not uncommon and should not delay feeding

Related surgical procedures


Gastric outlet obstruction due to hypertrophy of the pylorus impairs emptying of gastric contents into the duodenum. Thus, stomach contents can only exit via vomiting. This leads to a number of physiologic derangements, including:

  • Metabolic alkalosis
    • Respiratory compensation with hypoventilation and increased arterial pCO2
  • Secondary hyperaldosteronism from decreased blood volume
    • Hypokalemia
    • ± Hypernatremia
  • Hypochloremia

Signs and symptoms

  • Progressively worsening vomiting in the first weeks to 3 months of life
  • Dehydration
  • Poor feeding and weight loss
  • Palpable "olive-like" mass in right upper quadrant of abdomen[5]


  • Ultrasound



  • IV fluid resuscitation
  • Correction of electrolytes
  • Atropine can be used as an alternative to surgical correction with an 85-89% success rate[6]


A pyloromyotomy is the definitive treatment for pyloric stenosis. The procedure is most commonly performed laparoscopically, but can be performed open via a small incision. Incomplete correction requiring repeat surgery is rare.


Once corrected, pyloric stenosis generally has no long-term side effects or impact on the child's future health.


  • Male > female[7]
    • Firstborn males 4x likely
  • Caucasian > Hispanic > Black ≈ Asian
  • Exposure to erythromycin[8]


  1. van den Bunder, Fenne A. I. M.; Hall, Nigel J.; van Heurn, L. W. Ernest; Derikx, Joep P. M. (2020). "A Delphi Analysis to Reach Consensus on Preoperative Care in Infants with Hypertrophic Pyloric Stenosis". European Journal of Pediatric Surgery: Official Journal of Austrian Association of Pediatric Surgery ... [et Al] = Zeitschrift Fur Kinderchirurgie. 30 (6): 497–504. doi:10.1055/s-0039-3401987. ISSN 1439-359X. PMID 31958865.
  2. Cook-Sather, S. D.; Liacouras, C. A.; Previte, J. P.; Markakis, D. A.; Schreiner, M. S. (1997). "Gastric fluid measurement by blind aspiration in paediatric patients: a gastroscopic evaluation". Canadian Journal of Anaesthesia = Journal Canadien D'anesthesie. 44 (2): 168–172. doi:10.1007/BF03013006. ISSN 0832-610X. PMID 9043730.
  3. Park, Raymond S.; Rattana-Arpa, Sirirat; Peyton, James M.; Huang, Jia; Kordun, Anna; Cravero, Joseph P.; Zurakowski, David; Kovatsis, Pete G. (2021-02-01). "Risk of Hypoxemia by Induction Technique Among Infants and Neonates Undergoing Pyloromyotomy". Anesthesia and Analgesia. 132 (2): 367–373. doi:10.1213/ANE.0000000000004344. ISSN 1526-7598. PMID 31361669.
  4. Gibbs, M. K.; Van Herrden, J. A.; Lynn, H. B. (1975). "Congenital hypertrophic pyloric stenosis. Surgical experience". Mayo Clinic Proceedings. 50 (6): 312–316. ISSN 0025-6196. PMID 1127996.
  5. Macdessi, J.; Oates, R. K. (1993-02-27). "Clinical diagnosis of pyloric stenosis: a declining art". BMJ (Clinical research ed.). 306 (6877): 553–555. doi:10.1136/bmj.306.6877.553. ISSN 0959-8138. PMC 1677170. PMID 8461768.
  6. Aspelund, Gudrun; Langer, Jacob C. (2007). "Current management of hypertrophic pyloric stenosis". Seminars in Pediatric Surgery. 16 (1): 27–33. doi:10.1053/j.sempedsurg.2006.10.004. ISSN 1055-8586. PMID 17210480.
  7. Naffaa, Lena; Barakat, Andrew; Baassiri, Amro; Atweh, Lamya Ann (2019). "Imaging Acute Non-Traumatic Abdominal Pathologies in Pediatric Patients: A Pictorial Review". Journal of Radiology Case Reports. 13 (7): 29–43. doi:10.3941/jrcr.v13i7.3443. ISSN 1943-0922. PMC 6738493. PMID 31558965.
  8. Maheshwai, Nitin (2007). "Are young infants treated with erythromycin at risk for developing hypertrophic pyloric stenosis?". Archives of Disease in Childhood. 92 (3): 271–273. doi:10.1136/adc.2006.110007. ISSN 1468-2044. PMC 2083424. PMID 17337692.