Gastroenterolgy: Hirschsprung Disease Flashcards
What is Hirschsprung disease?
The absence of ganglion cells from the myenteric and submucosal plexuses of part of the large bowel, resulting in narrow, contracted segments.
(A developmental failure of these parasympathetic plexuses)
The abnormal bowel extends from…
The rectum for a variable distance proximally, ending in a normally innervated dilated colon
In 75% of cases the lesion is confined to..
The rectosigmoid
The entire colon is involved in…
10% of people
What age does it usually present?
Neonatal period
How does it present in the neonatal period?
Intestinal obstruction
Failure to pass meconium in first 24 hours of life
Abdominal distension and later bile stained vomit develop
What can rectal examination reveal?
Narrowed segment
Withdrawal of finger often releases gush of liquid stool and flatus
Temporary improvement in obstruction can lead to delay in diagnosis
Occasionally infants can present with severe…
Life threatening Hirschsprung enterocolitis during first few weeks of life
What is the presentation in later childhood?
Chronic constipation- usually profound
Abdominal distension
Usually without soiling
Growth failure
Is it more common in males or females?
Males
What genetic condition is it associated with?
Down’s syndrome
How is it diagnosed?
Abdominal X-ray with contrast dye - may show megacolon full of stool
Definitive: Suction rectal biopsy - demonstrating the absence of ganglion cells and large acetylcholinesterase positive nerve trunks (mucosa and submucosa extracted)
How is it managed?
Surgery - initial colostomy followed by anastomosing normally innervated bowel to anus
What is another term for it?
Congenital aganglionic megacolon
What are the layers of the GI tract?
Mucosa - epithelial layer, lamina propria, muscularis mucosa
Submucosa - contains Meissner’s (submucosal) plexus
Muscularis propria - circular muscle, Myenteric plexus, longitudinal muscle
Serosa
What is another term for the myenteric plexus?
Auerbach’s plexus
When the myenteric plexus is activated what does it primarily do?
Cause smooth muscle relaxation
What does the submucosal plexus do?
Helps control blood flow and epithelial absorption and secretion
What causes Hirschsprung’s disease?
During development - disruption of neuroblast cell migration (from neural crest cells). They start from mouth and around week 12 reach rectum. If this is disrupted, the nerve fibres do not develop in the rectum and parts of colon.
Without innervation, what movement is impaired?
Peristalsis - muscles cannot relax, so stay in default contracted position, which blocks the movement of faeces.
Why is the meconium usually past?
Within first 2 days after birth
Where do faeces build up?
Just before the obstruction - serious constipation and colon dilatation = megacolon, which is at risk of rupture
