FFinalistSouthampton · 2027
Child health
AKT · Child health/Neonatal & surgical

Pyloric stenosis

Hypertrophy of pyloric muscle

Overview

Hypertrophy of the gastric pylorus causing progressive gastric outlet obstruction, classically in first-born MALE infants at 2–8 weeks, with non-bilious projectile vomiting and a hypochloraemic hypokalaemic metabolic alkalosis.

Recognise

  • Non-bilious PROJECTILE vomiting after feeds at 2–8 weeks
  • Hungry, feeds again ("hungry vomiter")
  • Visible peristalsis; palpable "olive" mass in RUQ during a test feed
  • Weight loss, dehydration

Red flags

  • Severe dehydration, electrolyte derangement → resuscitate BEFORE surgery

Differentials & how to tell them apart

Gastro-oesophageal refluxnon-projectile, no alkalosis, no olive
Overfeeding/possetingthriving, no electrolyte change
Duodenal atresia/malrotationBILIOUS vomiting (obstruction distal to pylorus)
Gastroenteritisdiarrhoea, contacts

Investigations

Blood gas/U&E: HYPOCHLORAEMIC HYPOKALAEMIC METABOLIC ALKALOSIS (from vomiting HCl). USS: pylorus muscle thickness >3 mm, length >15–17 mm.

Management

Correct fluid/electrolytes first, then Ramstedt pyloromyotomy

  1. 1Resuscitate: IV fluids and correct the hypochloraemic hypokalaemic alkalosis FIRST.Gate: Surgery is NOT an emergency — never operate until fluids/electrolytes are corrected
  2. 2Definitive: Ramstedt pyloromyotomy.
IV fluid resuscitation + correct electrolytes — FIRST — never operate on a dehydrated alkalotic baby
Ramstedt pyloromyotomy — definitive surgery once corrected

Key points

The vomiting is NON-bilious (obstruction is proximal to the duodenum) — bilious vomiting means a more distal obstruction (malrotation) until proven otherwise.

Monitor & prognosis

Electrolytes/gas pre-op; post-op feeding.

Excellent after pyloromyotomy.

Source: Paediatric surgery guidance