GI - Hirschprungs

Question 1

Definition

Answer 1

Congenital disorder = defective relaxation and peristalsis of the distal colon leading to bowel obstruction due an aganglionic segment of the bowel

Question 2

Epidemiology

Answer 2

Neonatal period (May also be diagnosed in older children)
Male
Family history
Down syndrome (trisomy 21)
Delayed released of meconium ileus can be an indicator

Question 3

Pathophysiology

Answer 3

During normal prenatal development, neural crest cells migrate into the large intestine (colon).

Hirshprungs disease occurs due to a failure of ganglion cells derived from the neural to migrate into the autonomic Auerbach (myenteric) and Meissner (submucosal) plexuses within the bowel wall. These plexuses mediate gut motility and secretions.

Question 4

Signs

Answer 4

Older children: abdominal distention
Digital rectal examination: empty rectal vault or explosive stools on insertion of a gloved finger

Question 5

Symptoms

Answer 5

Bilious vomiting
Neonatal: delay in passing meconium (>24-48 hours)
Failure to thrive: poor weight gain
Older children: constipation

Question 6

Key feature of Hirschsprung’s disease

Answer 6

Delay in passing meconium in the first few days of life.
Normally 90% of babies pass meconium within 24 hours, 99% within 48 hours

Question 7

Diagnosis

Answer 7

FIRST LINE =
- Plain abdominal radiograph: non-specific features of bowel obstruction, such as a dilated colon
- Contrast enema: dilated colon followed by a segment of non-distended colon is the classic finding, this is known as the ‘transition zone’
GOLD STANDARD =
- Rectal suction biopsy = doesn’t require anaesthesia, and can be performed bedside.
- Definitive diagnosis = lack of ganglion cells in the sub mucosa and muscularis propria and presence of hypertrophied nerve fibres

Question 8

Rectal suction biopsy results

Answer 8

Lack of ganglion cells in the sub mucosa and muscularis propria
Presence of hypertrophied nerve fibres

Question 9

Initial Management

Answer 9

Initial decompression:
- Bowel irrigation = a tube inserted into the rectum and irrigated with saline solution (10-20ml) to clear out faeces and provide symptomatic relief from obstruction. This is a temporary measures in the acute setting whilst awaiting definitive surgery.
- Nasogastric tube: can be used to further aid decompression

Question 10

Definitive Management

Answer 10

Anorectal pull-through: usually performed in the first week of life and involves removal of the aganglionic distal segment of bowel and connecting the healthy section to the anus
SEVERE = Total colectomy

Question 11

Complications

Answer 11

Ischaemic enterocolitis: necrosis and eventual perforation of the affected segment in protracted cases carries a high mortality.