pyloric stenosis

Question 1

Define

Answer 1

Pyloric stenosis = hypertrophy of the pyloric muscle causing gastric outlet obstruction

• Presents at 2-8 weeks of age, irrespective of gestational age
• 4 x more common in boys
• Aetiology = hypertrophy of circular muscles of the pylorus
• Polygenic
• Associated with Turner’s syndrome
• 3-4 in 1,000 live births (0.3-0.4%); 15% have a FHx
• More common in caucasians

Question 2

Symptoms

Answer 2

Vomiting- increases frequency and forcefulness over time, ultimately becoming projectile

• Occurs ~30 minutes after a feed
• NON-BILIOUS

Hunger after vomiting- until dehydration leads to loss of interest in feeding
* Hunger -> dehydration -> loss of interest in feeding -> weight loss + depressed fontanelle

Signs of dehydration- reduced skin turgor, sunken eyes, increased capillary refill time

Vomiting stomach contents can result in hypochloraemic metabolic alkalosis with low plasma Na+ and K+

• HCO3- is elevated (metabolic alkalosis; H + HCO <-> CO2 and H2O)
• May progress to a dehydrated lactic acidosis (opposite biochemical picture)

Palpable ‘olive’ mass in RUQ
* This is where the pylorus is thick!!

Visible peristalsis in upper abdomen

Question 3

Investigations

Answer 3

Examination

Basic observations

Bloods- capillary blood gas (CBG), U&E, LFTs, FBC, glucose  hypochloraemic, hypokalaemic met alkalosis (high bicarbonate)

• As losing HCl in the stomach when vomiting, hence in a negative balance for H+ and Cl-
• Kidneys tries to rescue H+ by exchanging for Na+ and K+, so you may also get a low Na+ and K+ if the vomiting has been long-standing

DDx

GORD - presents usually shortly after birth

Gastritis - occurs usually with D

UTI - non-specific in neonates

Overfeeding

DIAGNOSIS

• A test feed is performed (unless immediate fluid resuscitation is required)- the baby is given a milk feed which will help calm the hungry infant.
• Gastric peristalsis may be seen as a wave moving from left to right across the abdomen
• Pyloric mass (feels like an olive) is usually palpable in the RUQ
• NOTE: if the stomach is distended with air, it will need to be emptied using an NG tube to allow palpation
• USS may be useful for confirmation- (diagnostic if muscle > 4mm thick, > 14mm length)

Question 4

Management

Answer 4

IV fluids resuscitation
* This is essential to correct the fluid and electrolyte disturbance before surgery
* This should be provided at 1.5 x maintenance rate with 5% dextrose + 0.9% saline

Definitive treatment is by performing a Ramstedt pyloromyotomy
* This involves dividing the hypertrophied muscle down to the mucosa (but NOT including the mucosa)
* Can be open (via periumbilical incision) or laparoscopic

Question 5

Complications

Answer 5

Complications of Pyloric Stenosis

Vomiting can lead to severe dehydration and weight loss and severe electrolyte disturbance

Surgical- bowel perforation, bleeding, persistent vomiting (incomplete pyloromyotomy)

Prognosis

Excellent unless diagnosis delayed and severe dehydration