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Pyloric stenosis

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    Intravenous fluids

    Key points

    1. Correction of fluid deficit, electrolyte and acid base abnormalities is the priority
    2. Surgical management can be delayed until the above are corrected


    Hypertrophic Pyloric Stenosis (HPS) usually presents between 2 and 6 weeks of chronological age with progressive non-bilious vomiting.

    Risk factors include: male, first born, parental history of HPS (especially if mother affected).




    • recurrent and progressively more forceful. May be projectile
    • soon after feeding
    • non-bilious
    • blood stained in up to 10% of cases
    • often hungry afterwards

    Weight loss or inadequate weight gain



    • Assess degree of dehydration
    • Weigh and plot on growth chart with previous weights if available

    Visible gastric peristalsis (may be more obvious following a feed)

    Pyloric mass

    • Located in the right upper quadrant at the lateral edge of the rectus abdominis muscle 
    • Best felt from the left side with the infant settled and supine 
    • May be difficult to palpate. May require repeated examinations or to wait for several minutes with hand on abdomen to feel

    Differential diagnoses:

    Urinary tract infection (UTI), gastroenteritis, gastrooesophageal reflux, surgical causes (eg volvulus, malrotation), congenital adrenal hyperplasia



    • Capillary or venous blood gas with electrolytes and glucose
    • Hypochloraemic hypokalaemic metabolic alkalosis may be seen – the degree of abnormality is proportionate to the duration of symptoms prior to presentation
    • Abdominal ultrasound can be used to investigate if the diagnosis is not established clinically (95% sensitive in the diagnosis of HPS)
    • Urine microscopy and culture to rule out UTI


    • Gain IV access
    • Stop oral feeds
    • Insert a nasogastric tube if profuse vomiting continues despite stopping feeds

    Fluid Management 

    Purpose Fluid Notes
    Resuscitation 0.9% Sodium Chloride Fluid Resuscitation as required. Not all infants will require fluid resuscitation
    Deficit 1000 mL 0.9% Sodium Chloride + 5% Glucose 

    Refer to dehydration and IV fluids guidelines.

    Include Potassium in IV fluids once urine output is adequate (1–2 mL/kg/hr)

    Maintenance (ongoing) 1000 mL 0.9% Sodium Chloride + 5% Glucose
    • Surgical correction of HPS is usually delayed until correction of dehydration, acid / base status and electrolyte disturbances 
    • It is particularly important to fully correct serum bicarbonate before surgery because of the risk of hypoventilation / apnoea post-operatively in the setting of a metabolic alkalosis

    Monitoring and management

    • Repeat blood gas with electrolytes 6 hourly initially and adjust fluids accordingly
    • Usually aim to fully correct fluid and electrolyte deficits within 48 hours
    • Blood bicarbonate levels can be used to monitor response to fluid therapy in HPS (therefore Plasmalyte is not used in the management of HPS as it contains bicarbonate precursors that may affect this process)

     Consider consultation with local paediatric team when

    Pyloric stenosis suspected — all confirmed cases should be managed as an inpatient

    Note: consult with a paediatric surgeon 

    Consider transfer when 

    Confirmed or high suspicion for pyloric stenosis

    Note: transfer to a paediatric centre early, once an initial management plan is in place

    For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services.

    Consider discharge when

    • Cleared by surgical team
    • Tolerating full oral feeds
    • Pain free

    Parent information sheet

    Pyloric Stenosis

    Last updated July 2019

  • Reference List

    1. Dalton, B et al 2016, ‘Optimizing Fluid Resuscitation in Hypertrophic Pyloric Stenosis’, Journal of Paediatric Surgery, vol. 51, no. 8, pp. 1279 – 1282 [Available from: viewed March 2019]
    2. Hunter C 2017, Pyloric Stenosis, BMJ Best Practice, viewed March 2019,  <>
    3. International Paediatric Endosurgery Group Guidelines Committee 2002, Guidelines for Surgical Treatment of Infantile Hypertrophic Pyloric Stenosis, IPEG, viewed March 2019, <>
    4. Jobson, M 2016, ‘Contemporary Management of Pyloric Stenosis’, Seminars in Paediatric Surgery, vol. 25, no. 4, pp. 219-224 [Available from:!/content/playContent/1-s2.0-S1055858616300178?returnurl=null&referrer=null viewed March 2019]
    5. Olive, AP et al 2019, Infantile hypertrophic pyloric stenosis, UpToDate, viewed March 2019, <>