L20: Inflammatory Diseases of the Bowel Flashcards
What parts of the large intestine does the superior mesenteric artery supply?
caecum to the splenic flexure
What part of the large intestine does the inferior mesenteric artery supply?
splenic flexure to rectum
What is the main function of the large intestine?
- absorb water + salts
- remove waste products
The large intestine does not have any villi. True or False?
True
Where is Meissner’s plexus located in the large intestine?
in the submucosa
Where is the Auerbach/Myenteric plexus located in the large intestine?
muscularis propria
Which parts of the large intestine does Hirschsprung’s Disease normally affect?
sigmoid colon + rectum
What is Hirschsprung’s Disease?
- congenital megacolon
- aperistaltic, narrow segment present causing a functional obstruction and dilation of proximal colon
- a/w RET gene mutation
Why does Hirschsprung’s Disease occur? (pathogenesis)
- arrested migration of parasympathetic neural crest cells into bowel wall
- absence of ganglion cells in Auerbach and Meissner’s plexus
Which mutation is associated with Hirschsprung’s Disease?
RET gene mutation
What is the clinical presentation of Hirschsprung’s Disease?
failure to pass meconium, constipation, abdominal distension, vomiting
What is the treatment of Hirschsprung’s Disease?
resection of the involved bowel
What are the 4 types of ischaemic bowel disease that affect the large intestine?
- Transmural Infarction
- Mural Infarction
- Mucosal Infarction
- Chronic Ischaemic Colitis
What is mural infarction of the large intestine?
necrosis of the mucosa and submucosa
What is mucosal infarction of the large intestine?
necrosis of the mucosa only
Mural and/or mucosal infarction of the large intestine is mainly caused by what?
hypoperfusion - especially in watershed areas
What are the clinical features/symptoms of a transmural infarction?
- severe abdominal pain
- bloody diarrhea
- decreased persistaltic sounds
- rigidity
What is angiodysplasia of the large intestine? Where does it normally occur?
- breakdown/dilatation of blood vessels
- usually in caecum and right colon
- usually in elderly
What is hereditary haemorrhagic telangiectasia?
- autosomal dominant disorder
- thin walled blood vessels in the mouth and GIT
- may rupture and bleed
What are haemorrhoids? How do they present?
- variceal dilatation of submucosal venous plexi around anus and lower rectum
- can be inside anus or on skin around anus
- presents w/ bright red stool and painful swelling around anus
What is necrotising enterocolitis? Which population does it occur in?
- occurs in neonates (occurs usually between day 2-4; up to 3 months)
- – premature + low birth weight infants
- acute necrotising inflammation of small and large bowel
Which population is necrotising enterocolitis most likely to occur in?
premature infants or low birth weight infants
Why does necrotising enterocolitis occur? [4]
combination of:
- ischaemia
- colonization of pathogenic organisms
- excess protein in lumen
- functional immaturity of gut
What is another name for pseudomembranous colitis?
antibiotic-associated colitis
What is antibiotic-associated colitis? (aka pseudomembrane colitis)
- characterized by pseudomembrane (adherent inflammatory exudate)
- occurs following a course of broad spectrum antibiotics
What is the treatment of antibiotic-associated colitis? (aka pseudomembrane colitis)
metronidazole, vancomycin
OR
faecal microbiota transplant (FMT)
List some of the characteristics of Crohn’s Disease
- affects any portion of the GIT
- segmental lesions/skip lesions
- transmural involvement
- aphthous ulcers that coalesce into serpentine ulcers
- a/w fistulas
What is cryptitis? What is crypt abscess? What are they associated with?
Cryptitis: neutrophils in the wall of the crypt
Crypt Abscess: collection of neutrophils within lumen of the crypt
a/w Crohn’s disease
What type of anaemia is associated with Crohn’s disease?
Iron Deficiency Anaemia*
Megaloblastic Anaemia - due to malabsorption of B12
List the systemic manifestations of Crohn’s disease
- arthritis
- uveitis
- erythema nodosum
- clubbing of fingers
List some of the characteristics of ulcerative colitis
- limited to mucosa + submucosa
- usually begins in rectum and extends proximally
- continuous
- relapsing and remitting
What is a complication of Ulcerative Colitis? (not systemic)
toxic megacolon
List the systemic manifestations of Ulcerative Colitis
Joint:
- migratory polyarthritis
- sacroiliitis
- ankylosing spondylitis
Skin:
- erythema nodosum
- necrotising skin lesion (pyoderma gangrenosum)
- clubbing
Liver:
- primary sclerosing cholangitis
Uveitis
What is diverticular disease and why does it occur?
- outpouching of the intestines
- almost always in sigmoid colon
- occurs due to increased pressure in intestines
List some of the complications of diverticulosis
- diverticulitis
- perforation
- adhesions
- fistula formation
- pericolic abscess formation
- inflammatory mass formation
- haemorrhage
- obstruction
Is intestinal obstruction more common in the large or small intestine?
small intestine as it has a smaller lumen
What is a hernia?
weakness in the wall of the peritoneal cavity - organs may get trapped
– incarceration then strangulation
What are adhesions of the GIT?
fibrous bands develop b/w loops of bowel or b/w organs and abdominal wall
– due to previous surgery, peritonitis, endometriosis..
What is intussusception?
telescoping of the proximal segment of the bowel into the distal segment
What is the most common cause of intussusception in the elderly?
almost always a tumour
What is the most common cause of intussusception in children?
most common cause = lymhoid hyperplasia
What is a volvulus?
twisting of a loop of bowel along its mesentery - cuts of blood supply and results in acute ischaemia
- elderly = sigmoid colon
- young adults = caecum
Where is a volvulus most likely in the elderly?
sigmoid colon
Where is a volvulus most likely in young adults?
caecum
