20. Large Bowel Disease Flashcards
Where is the plexus of meissner located?
Submucosa
Where is the plexus of auerback located?
Muscle
What is Hirschsprung’s disease?
Congenital megacolon due to arrested migration of neural crest cells: no meissner or auerbach plexuses so no peristalsis, causing a functional obstruction
What patient group is more likely to have Hirschsprung’s disease?
Male
Downes syndrome
What parts of the bowel are susceptible to Hirschsprung’s disease?
Rectum and sigmoid
What gene is associated with Hirschsprung’s disease?
RET gene
What are the clinical features of Hirschsprung’s disease?
Failure to pass meconium
Constipation, vomiting and abdominal distension
What are the complications of Hirschsprung’s disease?
Massive dilatation and perforation
Infection
What is the treatment for Hirschsprung’s disease?
Resect the part without ganglion cells
What part of the enteric tract is supplied by the superior mesenteric artery?
Caecum to splenic flexure
What part of the GIT is supplied by the inferior mesenteric artery?
Colon to rectum
What arteries supply the lower rectum?
Internal iliac and internal pudendal
What is a transmural infarction caused by?
Sudden occlusion of a major vessel causing infarction of all layers
What are the other types of infarction of the bowel?
Mural: mucosa and submucosa
Mucosal
What are the clinical features of transmural bowel infarction?
Severe abdominal pain
Bloody diarrhoea
Reduced peristaltic sounds
Rigidity
What are the clinical features of mucosal and mural infarcts?
Intermittent bloody diarrhoea
Non-specific abdominal complaints
What is angiodysplasia?
Dilatation of blood vessels in caecum and right colon
Seen in elderly as a result of wear and tear
What is hereditary haemorrhagic telangiectasia?
AD
Thin walled blood vessels in mouth and GIT which can rupture
What are risk factors for haemorrhoids?
Constipation
Pregnancy
Portal hypertension
What patient group gets necrotising enterocolitis?
Premature or low birth weight infants
Any time in first 3 months of life
What are the features of necrotising enterocolitis?
Ischaemia
Bacterial colonisation
Excess protein in lumen
Functional immaturity
What patient groups have higher risks of Crohn’s disease?
Females
White, Jewish
Peak in teens and 20s, minor peak in 50-60
Where is the most common area affected by Crohn’s disease?
Terminal ileum
What are the features of Crohn’s disease?
Segmental: affected areas are separated by normal
Transmural, affects all layers
Give examples of the transmural effects of Crohn’s disease?
Creeping fat
Dull serosa
Thickening of wall
What causes thickening of the bowel wall in Crohn’s disease?
Oedema, inflammation and fibrosis
What types of ulcers are seen in Crohn’s disease?
Aphthous
Serpentine/linear: ‘cobblestones’
Fissures
What are the microscopic features of Crohn’s disease?
Crypt architectural distortion
Inflammatory cells in all layers
Cryptitis and crypt abscesses
Non caseating granulomas
What is the difference between cryptitis and crypt abscesses?
Cryptitis is neutrophils in the wall of the crypt
Crypt abscesses are collections of neutrophils in the lumen
What are the clinical features of Crohn’s disease?
Relapsing and remitting abdominal pain, fever, bloody diarrhoea
Malabsorption
What types of anaemia are associated with Crohn’s disease?
Iron deficiency due to ulceration and bleeding
B12 deficiency due to involvement of terminal ileum
What are the complications of Crohn’s disease?
Obstruction Adhesions Fistula Malabsorption Increased risk of carcinoma
What structures can be fistulated in Crohn’s disease?
Small bowel and colon
Bladder
Vagina
Skin
What are the systemic manifestations of Crohn’s disease?
Arthritis
Uveitis
Erythema nodosum
Clubbing
What is the gross pathology of ulcerative colitis?
Begins in the rectum and spreads upwards continuously
Red mucosa
Broad ulcers
What are the microscopic features of ulcerative colitis?
Cryptitis and crypt abscesses
Architectural distortion of crypts
Epithelial dysplasia
No granulomas
What are the clinical features of ulcerative colitis?
Relapsing and remitting bloody mucoid diarrhoea, abdominal pain and tenesmus
Fever, weight loss, anaemia
What type of anaemia is seen in ulcerative colitis?
Only iron deficiency
What are the complications of ulcerative colitis?
Toxic megacolon caused by damage to the muscularis propia by inflammatory cells, destroying neuromuscular function
Neoplasia
What are the systemic manifestations of ulcerative colitis?
Arthritis, erythema nodosum, clubbing
Pyoderma gangrenosum
PSC
Uveitis
How does a low fibre diet cause diverticular disease?
Low fibre > low stool bulk > increased peristalsis > increased pressure
What are the clinical features of diverticular disease?
Normally asymptomatic
Cramping, lower abdominal pain, tenesmus
What complications are associated with diverticular disease?
Diverticulitis Perforation Adhesions Fistula with bladder Pericolic abscess formation Haemorrhage Obstruction
What is the cause of intussusception in the elderly?
Tumour at the leading edge
Which part of the GIT is involved in volvulus in the elderly and young adults?
Elderly: sigmoid
Young adults: caecum
