GI - Hirschsprung's Disease

Question 1

What is Hirschsprung’s disease?

Answer 1

A congenital condition where nerve cells of the myenteric plexus are absent in the distal bowel and rectum.

Question 2

Risk Factors of Hirschsprung’s Disease (6).

Answer 2

1. Genetics : Family History.
2. Down’s Syndrome.
3. Neurofibromatosis.
4. Waardenburg Syndrome (genetic condition that causes blue eyes, hearing loss, patches of white skin and hair).
5. MEN Type II.
6. Males (3x commoner).

Question 3

Differential Diagnoses of Childhood Constipation (7).

Answer 3

1. Idiopathic (Majority).
2. Dehydration & Low Fibre Diet.
3. Medications e.g. Opiates.
4. Anal Fissure.
5. Over-Enthusiastic Potty Training.
6. Hypothyroidism or Hypercalcaemia.
7. Learning Disability.

Question 4

What does the severity of the presentation/age at diagnosis depend on?

Answer 4

Extent of bowel that is affected.

Question 5

Clinical Features of Hirschsprung’s Disease (7).

Answer 5

1. Delay in Passing Meconium (More than 24 Hours).
2. Acute Intestinal Obstruction Shortly After Birth.
3. Chronic Constipation Since Birth.
4. Abdominal Pain and Distension.
5. Vomiting.
6. Poor Weight Gain & Failure to Thrive.
7. Forceful Evacuation of Meconium after a DRE.

Question 6

Presentation of Hirschsprung’s disease in
A. Neonates (main clinical feature).
B. Older Children (main clinical feature).

Answer 6

A. Delay/Failure to Pass Meconium.

B. Constipation or Abdominal Distension.

Question 7

Neurology of Gastrointestinal System (3).

Answer 7

1. Enteric Nervous System (part of ANS) controlled by Myenteric Plexus (Auerbach’s Plexus).
2. Runs along the bowel (in wall).
3. Responsible for peristalsis of large bowel.

Question 8

Pathophysiology of Hirschsprung’s Disease (4).

Answer 8

1. Developmental failure of Parasympathetic Auerbach and Meissner Plexuses.
2. Parasympathetic neuroblasts fail to migrate from neural crest to distal colon.
3. During foetal development, parasympathetic ganglion cells start higher in GI tract and gradually migrate down to distal colon and rectum but here, some don’t travel all the way down the colon.
4. Result : Unco-ordinated peristalsis and functional obstruction (aganglionic section does not relax so constricts = loss of movement of faeces and obstruction in the bowel and proximal to obstruction, the bowel becomes distended and full).

Question 9

What is Total Colonic Aganglionosis?

Answer 9

Hirschsprung’s disease where the entire length of the colon exists without innervation.

Question 10

Investigations of Hirschsprung’s disease (2).

Answer 10

1. Gold Standard : Rectal Biopsy (Histology = Absence of Ganglionic Cells).
2. AXR = Intestinal Obstruction and Features of HAEC.

Question 11

Management of Hirschsprung’s Disease (2).

Answer 11

1. Initial = Rectal Washouts and Bowel Irrigation.

2. Definitive = Surgical Removal of Aganglionic Section of Bowel (Anorectal Pull Through Procedure).

Question 12

Definition & Epidemiology of HAEC.

Answer 12

Hirschsprung-Associated Enterocolitis : Inflammation and Obstruction of the Intestine. It occurs in around 20% of neonates with Hirschsprung’s disease.

Question 13

Clinical Features of HAEC (4).

Answer 13

Within 2-4 weeks of birth :

1. Fever.
2. Abdominal Distension.
3. Diarrhoea (often with blood).
4. Features of Sepsis.

Question 14

Prognosis of HAEC.

Answer 14

Life-threatening - can lead to toxic megacolon and perforation of the bowel.

Question 15

Management of HAEC.

Answer 15

1. Urgent IV antibiotics.
2. Fluid resuscitation.
3. Decompression of the obstructed bowel.

Question 16

Prognosis of Hirschsprung’s disease.

Answer 16

Potentially long-term disturbances in bowel function and degree of incontinence following corrective surgery.