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Pyloric Stenosis

Pyloric stenosis ( also known as Infantile hypertrophic pyloric stenosis IHPS ) happens due to marked hypertrophy and hyperplasia of the circular and longitudinal muscles leading to gastric outlet obstruction in infants


IHPS is the most common cause of gastric outlet obstruction in the 2-12 week age group requiring surgery Described for the 1st time by Harold Hirschsprung in 1888 who believed that the condition was congenital IHPS is the most common gastrointestinal disease of the newborn Seen more commonly in white males ( 4 : 1 M/F ratio )- seen less commonly in Indian , Asian and Black populations One paper reports that the highest incidence is in N Europe In the UK it is seen in upto 4 in 1000 live births Peak age of presentation is between 5 -6 weeks with most infants presenting between 2-12 weeks , A familial link is known but the hereditary pattern is polygenic


Etiology The etiology of IHPS remains uncertain but several points or potential risk factors
 have been noted which may helpful It is not a congenital condition and research has shown that IHPS is not present at birth Environmental and genetic conditions are thought to be contributing factors ie multifactorial pattern Environmental factors include
- feeding method ( breast vs formula feeding )
- seasonal variability
- transpyloric feeding in premature infants IHPS is known to be associated with certain genetic conditions for e.g
- Cornelia de Lange syndrome & Smith-Lemli-Opitz syndrome
- chromosomal abnormalities as translocation of Ch 8 & 17 and partial trisomy of chromosomes Parental history of IHPS particularly if the mother had IHPS Use of macrolide antibiotics in young infants Postnatal exposure to erythromycin Other reported risk factors include
- first born male ( controversial )
- cesarean section delivery
- heavy smoking by mother during pregnancy
- infants born at an early gestational age
- infants born with small for gestational age
- congenital malformation.


Hypertrophy of pylorus muscle causes variable gastric outlet obstruction which provokes increasingly severe episodes of projectile vomiting.


Presentation- Period of normal feeding for 1st 2-3 weeks of life The infant is well at birth Age 2 to 8 weeks ( this varies to 3-12 weeks in literature ) One paper quotes median age at presentation at 30.8 days Post-prandial non-bilious recurrent projectile vomiting which can be progressive Usually 10-30 minutes after feeding Insatiable appetite and may cry inconsolably
- hungry afterwards Depending upon the duration of symptoms
- weight loss or inadequate weight gain
- dehydration
- always non-bilious but can be blood stained in up to 10 % cases 
- failure to thrive Distended stomach.


Examination – Infant may be dehydrated and underweight Signs of dehydration include
- depressed fontanelle
- dry mucous membranes
- decreased tearing
- poor skin turgor & lethargy Visible peristalsis waves across the upper abdomen prior to vomiting A palpable olive shaped mass in the upper right quadrant of the epigastric region is pathognomic for IHPS 
-this may not be found very quickly and may be more obvious following a feed
- it is best felt from the left side with the infant settled and supine
- you may have to examine several times and to wait for several minutes to feel
- this is firm , non tender pylorus measuring about 1-2 cm and can be found in about 60 % to 80 % of infants In the paediatric ward they may use what is called test feed to help increase the possibility of palpating the hypertrophied pylorus.


It is critical to elicit in history that the vomiting is non-bilious
- bilious vomiting suggests a more serious cause like malrotation with volvulus
- adrenal crisis , pylorospasm , hiatal hernia , preampullary duodenal stenosis Other differentials include
- gastroesophageal reflux ( IHPS is often misdiagnosed as GORD in early stages )
- gastroenteritis / UTI
- acute renal failure
- sepsis
- hernia 
- colic
- constipation
- necrotizing enterocolitis
- Hirschsprung disease
- testicular torsion
- appendicitis.


Ultrasound is reliable , highly sensitive , highly specific , easily performed, cost-effective and is now the standard imaging technique Classical electrolyte imbalance ( late presentation ) of pyloric stenosis is hypochloremic hypokalaemic metabolic alkalosis – this will need medical stabilization with rehydration and correction of electrolyte imbalance prior to surgery Treatment of IHPS is surgical and is called pyloromyotomy Surgical approach can be laparoscopic / open Operation is curative and has very low morbidity.


Outcome is excellent in developed nations No long term sequelae Transient post-operative vomiting is not uncommon In some infants if the vomiting persists 5 days after the surgery further radiological studies such as upper GI series may be needed.


Late presentation is very uncommon ( IHPS is rare beyond 12 weeks ) but possible and Ali F. El- Mayoof have reported a case of HPS in a 7 month old female baby ( Journal of Paediatric Surgery Case Reports 2018 ) and advice that HPS should be kept in mind in any child who presents with growth retardation , non bilious vomiting beside metabolic derangement after exclusion of medical causes


  1. Pyloric stenosis The Royal Children’s Hospital Melbourne Clinical Practice Guidelines : Pyloric stenosis (

  2. Garfield K, Sergent SR. Pyloric Stenosis. [Updated 2020 Nov 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from:
  3. BMJ Best Practice Pyloric Stenosis summary Pyloric stenosis – Symptoms, diagnosis and treatment | BMJ Best Practice US
  4. The Clinical Features of Infantile Hypertrophic Pyloric Stenosis in Chinese Han Population: Analysis from 1998 to 2010
    Feng Z, Nie Y, Zhang Y, Li Q, Xia H, et al. (2014) The Clinical Features of Infantile Hypertrophic Pyloric Stenosis in Chinese Han Population: Analysis from 1998 to 2010. PLOS ONE 9(2): e88925.
  5. Ultrasound Value in the Early Diagnosis and Exclusion of Idiopathic Hypertrophic Pyloric Stenosis: 10 Years’ Experience at Babylon Governorate
    Ahmed S Resheed* Pediatric Surgery Specialist, Al-ramadi Maternity and Pediatric Teaching Hospital, Al-Anbar, Iraq J Gen Pract (Los Angel), an open access journal ISSN:2329-9126

    Diagnosing Infantile Hypertrophic Pyloric StenosisClinician Reviews. 2012 September;22(9):10, 12-15 Diagnosing Infantile Hypertrophic Pyloric Stenosis | Clinician Reviews (


  7. Sommerfield T, Chalmers J, Youngson G, Heeley C, Fleming M, Thomson G. The changing epidemiology of infantile hypertrophic pyloric stenosis in Scotland. Arch Dis Child. 2008 Dec;93(12):1007-11. doi: 10.1136/adc.2007.128090. Epub 2008 Feb 19. PMID: 18285388. ( Abstract )
  8. Andrew R Ross, Paul R.V. Johnson,
    Infantile hypertrophic pyloric stenosis,
    Surgery (Oxford),
    Volume 37, Issue 11,
    Pages 620-622,
    ISSN 0263-9319, ( Abstract )
  9. Epidemiological Features of Infantile Hypertrophic Pyloric Stenosis in Taiwanese Children: A Nation-Wide Analysis of Cases during 1997–2007
    Leong MM, Chen SCC, Hsieh CS, Chin YY, Tok TS, et al. (2011) Epidemiological Features of Infantile Hypertrophic Pyloric Stenosis in Taiwanese Children: A Nation-Wide Analysis of Cases during 1997–2007. PLOS ONE 6(5): e19404.
  10. Gotley LM, Blanch A, Kimble R, Frawley K, Acworth JP. Pyloric stenosis: a retrospective study of an Australian population. Emerg Med Australas. 2009 Oct;21(5):407-13. doi: 10.1111/j.1742-6723.2009.01218.x. PMID: 19840091. ( Abstract )
  11. Jianghu Zhu, Tingting Zhu, Zhenlang Lin, Yi Qu, Dezhi Mu,
    Perinatal risk factors for infantile hypertrophic pyloric stenosis: A meta-analysis,
    Journal of Pediatric Surgery,
    Volume 52, Issue 9,
    Pages 1389-1397,
    ISSN 0022-3468,
    ( Abstract
  12. Camilla Krogh, Sanne Gørtz, Jan Wohlfahrt, Robert J. Biggar, Mads Melbye, Thea K. Fischer, Pre- and Perinatal Risk Factors for Pyloric Stenosis and Their Influence on the Male Predominance, American Journal of Epidemiology, Volume 176, Issue 1, 1 July 2012, Pages 24–31,
  13. Krogh C, Gørtz S, Wohlfahrt J, Biggar RJ, Melbye M, Fischer TK. Pre- and perinatal risk factors for pyloric stenosis and their influence on the male predominance. Am J Epidemiol. 2012 Jul 1;176(1):24-31. doi: 10.1093/aje/kwr493. Epub 2012 May 2. PMID: 22553083. ( Abstract )
  14. Lund MariePasternak BjörnDavidsen Rie BFeenstra BjarkeKrogh CamillaDiaz Lars J et al. Use of macrolides in mother and child and risk of infantile hypertrophic pyloric stenosis: nationwide cohort study 
  15. Ali F. Al-Mayoof, Ibraheem K. Doghan,
    Late onset Infantile Hypertrophic Pyloric Stenosis,
    Journal of Pediatric Surgery Case Reports,
    Volume 30,
    Pages 22-24,
    ISSN 2213-5766,
    ( Abstract




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