Pyloric stenosis

ACEM Fellowship

Table of Contents

Introduction

Rare in first week of life
Typically weeks 2-8 of age
Protracted vomiting and hungry
Idiopathic diffuse hypertrophy and hyperplasia of circular muscle fibres of pylorus leading to gastric outlet obstruction
2-4/1000 live births in developed countries
4-5x more common in males
Family history is a risk factor
First-born males are most at risk

Initially regurgitation and non-projectile vomiting, then gradually vomiting becomes projectile (during or soon after feeding)
Can be intermittent or after every feed
Hungry++
Vomiting is non-bilious but can have blood streaks (in up to 10%)
Stool amounts can be very small
If late presentation, severely dehydrated, lethargic, malnourished and metabolically deranged hypokalaemic, hypochloraemic metabolic alkalosis
Always consider in previously refluxing/posseting baby whose regurgitation changes in character
Takes time for clinical and USS findings to develop, so do not rule out if symptoms persist

Gastric distension, visible peristalsis from LUQ to epigastrium and palpable olive in RUQ/midline
- Need empty stomach and relaxed anterior abdominal wall for palpation
Palpation during test feed may reveal olive
Need USS to exclude diagnosis at any given point in time
Paradoxical aciduria (renal sodium conservation at expense of hydrogen ions)
With increasing dehydration, renal potassium losses are amplified in order to retain sodium and water

USS diagnostic imaging of choice
Accuracy near 100%
Bull’s eye on cross-section
Pylorus muscle thickness >4mm and pyloric channel length >17mm have PPV >90%
- Lower limits in infants <30 days old

GORD
UTI
Oesophageal achalasia
Hiatus hernia
Overfeeding
Adrenal insufficiency
- Frequent vomiting but usually metabolic acidosis and elevated serum potassium and sodium
Metabolic disorders
- Usually other clues i.e. seizures, coma, hypoglycaemia

Resuscitation over 24-48 hours with N/saline + 5% dextrose
Replace potassium (20mmol/L KCl) and chloride (in N/S)
Ramstedt pyloromyotomy once rehydrated, bicarbonate in normal range and chloride >90mmol/L
- If bicarb not corrected, risk of apnoea/hypoventilation post-operatively

Last Updated on November 20, 2021 by Andrew Crofton