Pyloric Stenosis
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  • More common in boys (4:1)
  • Often a maternal family history
  • Increased risk if siblings were affected
  • Erythromycin exposure in first few weeks of life


There is a functional obstruction of the pyloric sphincter, as the muscle in this region hypertrophies. This ultimately results in almost complete obstruction.

Clinical features

Presents at 2-7 weeks of age – and is not related to gestational age

Projectile vomiting (non-bile stained), in an otherwise well child

  • Typically occurs after each feed
  • This increases in severity and frequency as the child continues to grow
  • It really is projectile! – hits the walls / ceiling in some cases
  • The child is usually otherwise well – in contrast to other causes of vomiting in neonates
  • Obvious continued hunger despite vomiting. Only in the later stages when they are severely dehydrated will the child lose interest in feeding.
  • Hypochloraemic alkalosis (metabolic alkalosis due to vomiting), and Hypokalaemia
  • Failure to thrive / weight loss / poor weight gain
  • DehydrationCheck for:
    • Skin turgor
    • Sunken eyes
    • Moist mucous membranes
  • When dehydration is marked and severe, the child may not be keen to feed


  • Milk Test – Give the child a normal milk feed. A wave of peristalsis should be visible across the abdomen from left to right
  • Examination
  • Pyloric olive – a 2-3cm mass that can sometimes be felt in the URQ. Usually mobile
  • USS – Often used to confirm diagnosis of sphincter hyperplasia. Pylroci muscle usually >4mm thick (normal <2cm)
  • Barium Meal – may be rarely used in cases when diagnosis is not certain. It will shows the string sign of an elongated and narrowed pyloric sphincter.


  • Initial Management – Correct fluid and electrolyte imbalances (if present)
  • Surgery – Ramstedt pyloromyotomy – the excessive muscle is removed, but all gastric mucosa is left intact. Post-operatively the baby can usually feed normally within 24 hours of surgery



  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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