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Pyloric Stenosis

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  • Congenital hypertrophy of the pyloric muscles at the end of the stomach causing gastric outlet obstruction.


  • 2-4 per 1000 live births in the US.

  • Incidence is 1.4 cases per 10,000 live births according to a study done from

  • ​1990-2008 by Riyadh Military Hospital.

  • More common in males with M: F ratio of (5:1).


  • Most common cause is idiopathic.

  • Other causes:

Pyloric stenosis is the disease of firsts (1st):

  • In 1st born child (30%).

  • Presents in the 1st month.

  • Vomiting is the 1st event to happen after feeding.

  • 1st thing in management is correcting the electrolyte disturbance. 


  •  Maternal smoking

  •  Bottle feeding

  •  Formula milk


  • 200-fold higher rate among monozygotic twins and a 20-fold increase among dizygotic twins or siblings.

  • Associated with Turner and Edwards syndromes.


Macrolide antibiotic use (erythromycin, and clarithromycin) during the first two weeks of age.

Clinical Presentation: 

  • The hallmark characteristic is non-bilious projectile vomiting:

    • Dehydration, and weight loss.

  • Usually present during the first month (3-6 weeks of age):

    • But can present late up to 6 month of age.

  • Because of vomiting:

    • They usually have hypochloremic, hypokalemic metabolic alkalosis.

  • During physical exam:

    • Succussion splash during Auscultation.

    • Olive sign on palpation of the epigastric area.

    • Visible gastric peristaltic waves in the left lower quadrant. 



  • Blood laboratory electrolytes show ↓K+, ↓Cl- with metabolic alklasosis 

  • Best initial test is abdominal ultrasound:

    • Thickening of the pyloric sphincter

  • Most accurate diagnostic test is upper GI barium series showing:


String sign


Figure 1: Thin column of barium leaking.


Mushroom (Umbrella)  sign 


Figure 3: Impression made by the hypertrophic pylorus against the duodenum.


Shoulder sign


Figure 2: Filling defect in the antrum due to inward displacement of the muscle.


Railroad track sign 


Figure 4:Excess mucosa will lead to formation of two barium columns. 


  • Stabilize the patient and assess rehydration (half NS with 5%D and KCl):

    • Assess the benefit of immediate fluid restriction.

    • Electrolyte replacement.

  • NGT to decompress the bowel.

  • Surgical pyloromytotomy is the definitive treatment:

    • Oral feeding should be restarted after 12-24 hours post surgery. 


  • Le, Tao, and Kendall Krause. First Aid For The Basic Sciences. New York: McGraw-Hill Medical, 2012. Print.

  • Lissauer, Tom, Graham Clayden, and Alan Craft. Illustrated Textbook Of Paediatrics. Edinburgh: Mosby, 2012. Print.

  • Cvetnic, William G, Eduardo Pino, and Christine E Koerner. USMLE Step 2 CK Pediatrics. [New York]: Kaplan, 2011. Print.

  • Fischer, Conrad. Master The Boards. Print.

  •,. 'Infantile Hypertrophic Pyloric Stenosis'. N.p., 2015. Web. 15 Nov. 2015.

  • al-Salem AH, et al. 'Infantile Hypertrophic Pyloric Stenosis And Congenital Diaphragmatic Hernia. - Pubmed - NCBI'. N.p., 2015. Web. 15 Nov. 2015.

  • Kliegman, Robert. Nelson Textbook Of Pediatrics. Print.

  •,. 'Infants With Vomitting'. N.p., 2015. Web. 15 Nov. 2015. (Figure 1).

  •,. 'Sign In'. N.p., 2015. Web. 15 Nov. 2015. (Figure 2).

  •,. 'Pediatric Radiology'. N.p., 2015. Web. 15 Nov. 2015. (Figure 3).

  •,. 'Learningradiology-Hypertrophic, Pyloric Stenosis'. N.p., 2015. Web. 15 Nov. 2015. (Figure 4).

  • Shah, Samir S, Jeanine C Ronan, and Brian Alverson. Step-Up To Pediatrics. Print.

  • Kaplan Step 1 video, Pathology, 2015. 



Written by:         Roaa Amer

Reviewed by:      Adel Yasky
                             Lama Al Luhidan

Web publisher:  Adel Yasky

                            Bayan Alzomaili

Audio recording:


Read by: Bayan Alzomaili

Directed by: Rana Alzahrani

Audio production: Bayan Alzomaili

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