Congenital Hypertrophic Pyloric Stenosis

Question 1

Aetiology

Answer 1

• genetic and environmental factors
• familial tendency (male infants, first born, monozygotic twins)
• administration of macrolide antibiotics (erythromycin) to mother in late pregnancy or infant in the first 2 weeks of life

Question 2

Pathology

Answer 2

• disturbance in nitric oxide neurotransmission–> intense work hypertrophy of adjacent circular pyloric muscle–> abnormality of ganglion cells of myenteric plexus or failure of pyloric sphincter to relax

Question 3

Clinical feature

Answer 3

• projectile vomiting
• vomit never contain bile
• takes food avidly immediately after vomiting (always hungry)
• failure to gain weight
• dehydration–> constipated
• visible peristalsis of dilated stomach seen in epigastrium
• palpable pyloric tumour (firm ‘bobbin’ in right upper abdomen)

Question 4

Differential diagnosis

Answer 4

• enteritis: accompanies with diarrhoea
• neonatal intestinal obstruction: symptoms within one or two days of birth and vomit contains bile
• intracranial birth injury
• overfeeding: no other features to suggest pyloric stenosis apart from vomiting

Question 5

Special investigation

Answer 5

• clinical features are characteristic and palpable pyloric mass –> no further investigation
• ultrasound scan: thickened and elongated pylorus and large stomach
• abdominal x ray: dilated stomach with minimal gas in bowel
• barium metal: pyloric obstruction with characteristic shouldering of pyloric antrum due to impression made by hypertrophied pyloric muscle

Question 6

Treatment

Answer 6

• gastric lavage and fluid replacement (saline with added potassium chloride): prolonged vomiting–> dehydrated with hypochloraemic metabolic alkalosis
• Ramstedt’s pyloromyotomy: longitudinal incision is made through hypertrophied muscle of pylorus down to mucosa and cut edges are separated (laparoscopically)–> give glucose water 3 hours after operation and followed by 3-hourly milk feeds which steadily increased in amount