Pyloric stenosis

Question 1

How many live births does pyloric stenosis occur in?

Answer 1

1 in 500-1000

Question 2

Describe the gender ratio of pyloric stenosis

Answer 2

4 males for every 1 female

Question 3

What is pyloric stenosis characterised by?

Answer 3

Progressive hypertrophy of the pyloric muscle, causing gastric outlet obstruction

Question 4

List some risk factors of pyloric stenosis

Answer 4

Male gender

Family history

Question 5

When does pyloric stenosis commonly present

Answer 5

4-6 weeks of age

Question 6

Describe the clinical presentation from history of pyloric stenosis

Answer 6

Non-bilious, projectile vomiting after every feed 
Babies continue to be hungry 
Haematemesis
Weight loss
Dehydration - mild to hypovolaemic shock

Question 7

What can be seen on examination in pyloric stenosis?

Answer 7

Visible peristalsis

Palpable olive shaped pyloric mass

Question 8

List a differential for pyloric stenosis

Answer 8

Gastroenteritis 
Gastro-oesophageal reflux - sandifer syndrome 
Overfeeding
Sepsis
UTI
Food allergy

Question 9

What should you be thinking of if the vomit is bilious?

Answer 9

Malrotation

Question 10

What investigations should be done for pyloric stenosis?

Answer 10

Test feed with NG tube in situ and stomach aspirated - feel the pyloric mass and observe for visible peristalsis

Ultrasound

Blood gas

Question 11

Give the dimensions of pyloric stenosis on ultrasound

Answer 11

Thickness >3mm
Length >15mm
Diameter >11mm

Question 12

What picture will be seen on a blood gas in pyloric stenosis?

Answer 12

Hypochloreamic
Hypokalaemic
Metabolic alkalosis

Question 13

Describe the mechanism behind the metabolic abnormality in pyloric stenosis

Answer 13

Loss of hydrochloric acid with repeated vomiting of stomach acid causing a hypochloraemia and metabolic alkalosis
Kidneys then exchange potassium to retain protons to attempt to compensate, leading to a hypokalaemia

Question 14

Describe the management of pyloric stenosis

Answer 14

Peri-operatively it is important to correct any underlying metabolic abnormalities

NG tube and stop oral feeding - aspirate 4hrly

Rehydration

Regular blood gases and U&Es

Surgery - Ramstedts pyloromyotomy

Question 15

How much fluid may be required to correct acute hypovolaemia

Answer 15

10-20ml/Kg fluid boluses

Question 16

How should rehydration be commenced after NG tube insertion?

Answer 16

150ml/Kg/day using crystalloid

Question 17

How is a Ramstedt’s pyloromyotomy carried out?

Answer 17

Laparoscopically or through a supra-umbilical incision and muscle divided along down the mucosa

Question 18

When can babies resume feeding after the operation?

Answer 18

6 hours

Question 19

List some complications of pyloric stenosis

Answer 19

Pre operative- hypovolaemia and apnoea

Post operative - wound dehiscence, infection, bleeding, perforation and incomplete myotomy

Question 20

Why might babies vomit after the surgery?

Answer 20

Gastric distension and dysmotility

Or incomplete myotomy