6.4 Disorders of the Lower Gastrointestinal Tract Flashcards
(31 cards)
Are there villi or microvilli in the large intestine? What about circular folds?
- No villi/microvilli
- No circular folds
Outline the autoimmune mechanics of coeliac disease at a cellular level
- Specific MHC class II molecules that present gluten as a pathogen
- Picked up by autoreactive T cell
- Downstream immune activation and attacking of the small bowel
GI/extraintestinal symptoms of coeliac disease
GIT symptoms:
- Diarrhoea, flatulence, abdo pain, bloating
- Iron deficiency anaemia/other deficiencies
- Weight loss
- Fatigue
Extraintestinal:
- Skin blistering
- Other autoimmune diseases
- Osteoporosis
Coeliac disease Ix
- Gluten challenge diet (like a shitty viral video)
- Blood tests for antibodies
- Endoscopy/small intestine biopsy
Symptoms/signs of IBS
- Bloating
- Abdo pain
- Diarrhoea
- Constipation
What investigations/symptoms might we check for to determine if a patient has functional bowel disease like IBS?
Symptoms: weight loss, rectal bleeding, perianal symptoms, mouth ulcers
Investigations: Iron studies, CBC (?anaemia), CRP, faecal calprotectin, raised platelets, low albumin
What are the three broad characteristic principles of IBD pathogenesis?
- Defective host interactions with intestinal microflora (a war is being waged)
- Epithelial dysfunction (craters on the battlefield)
- Mucosal inflammatory response, driven by T cells
Extraintestinal symptoms of IBD
- Anterior uveitis
- Arthritis
- Osteopenia/porosis
- Thromboembolic event
Crohn’s Symptom
(Intermittent Attacks)
- Malabsorption
- Weight loss
- Perianal fissures
What macroscopic changes can Crohn’s make to the GI tract?
- Transmural inflammation
- Thickened/oedematous mesentery
- Strictures
- “Cobblestoning” fibrosis and ulceration
- Skip lesions
Crohn’s complications
- Bowel obstruction
- Ulcers
- Malabsorption
- Anaemia
- Carcinoma
What is the pattern of distribution of ulcerative colitis. How deep is the ulceration?
- Starts in rectum
- Spreads proximally
- Inflammation is more superficial than crohn’s
Ulcerative colitis symptoms
(Mostly intermittent attacks)
- Blood or pus in stool
- Diarrhoea
- Urgency
Describe acute severe ulcerative colitis
- > 6 bloody bowel motions/day
- One of: elevated HR, temp, CRP, or low Hb
- This is a medical emergency
Diverticulosis mechanism
- Increased intraluminal pressure from straining during defecation (due to deficiency in vegetable fibre)
- Causes mucosal “blowouts”, and circular muscle hypertrophy
- Plus, with age, tensile colonic strength decreases
- Causes diverticula to form
Diverticulitis mechanism
- Inspissated (thickened) stool gets trapped in diverticula
- Causes inflammation and localised ischaemia
- Bacteria may breach mucosa
Symptoms/investigations for acute diverticulitis
Symptoms: pain (usually left iliac fossa), fever, malaise, anorexia, change in bowel habirt, fever
Bloods: WCC elevated
Imaging: CT is best
How do we manage acute diverticulitis? What if there’s no initial improvement?
- Nil orally
- IV fluids
- IV antibiotics
- Analgesia
If no improvement: surgery
How does diverticular abscess differ from acute diverticulitis? How do we treat it?
- Walled off diverticulum
- Treated w/ IV antibiotics, radiological drainage, resection
(Smaller may go away on own; larger often need drainage and resection)
What are the two most common types of colonic fistula formed due to diverticulosis?
- Colovesical
- Colovaginal
What are some complications of diverticulitis?
- Fistula formation
- Bleeding
- Abscess occurrence
- Obstruction/stricture from recurrent
What must we always exclude if we’re considering diverticulosis? How?
Colorectal cancer (do a colonoscopy 6 weeks after event, to let mucosa calm down and reduce rupture risk)
Why is the appendix more likely to become gangrenous and perforate, as seen in appendicitis?
- End arterial supply
- More likely to become gangrenous and perforate
Mechanistically, what is the most likely cause of appendicitis?
Luminal obstruction
