Pathophysiology of the colon Flashcards
Diagnosis of Inflammatory Bowel Disease: when to suspect and how to diagnose
When:
Suggestive symptoms (e.g., diarrhea, crampy abd pain, bleeding) lasting > 2 weeks
Negative work-up for other causes of colitis (infection, ischemia, medications)
Extrai-ntestinal symptoms
How:
Imaging may be suggestive
Direct visualization and biopsy = gold standard
UC vs Crohn’d disease symptoms
UC: Diarrhea, Weight loss, Fatigue, Lower abd pain, Hematochezia, Mucus in stool, Tenesmus
Crohn’s: Diarrhea, Weight loss, Fatigue, Mid or lower abd pain, Nausea/vomiting, Fistula symptoms
Macroscopic differences btwn UC and Crohn’s
Crohn’s: Entire GI tract, fistulae possible, strictures common, “skip lesions”, transmural inflammation, deep/linear ulcers, marked fibrosis, granulomas (20%), can have obstruction, can have malabsorption, malignant potential with colonic involvement, common recurrence after colectomy, no toxic megacolon
UC: Colon only, no fistulae, no strictures, diffuse distribution, inflammation affects mucosa +/- SM, superficial/confluent ulcers, mild to no fibrosis, no granulomas, no obstruction, no malabsorption, yes malignant potential, no recurrence after colectomy, yes toxic megacolon
Extraintestinal manifestations of IBS
Mostly seen in UC
Eye: Scleritis, episcleritis
Skin: Pyoderma gangrenosum, erythema nodosum
Liver: Primary sclerosing cholangitis (PSC)
Joints: Sacroiliitis, Ankylosing spondylitis
IBD - management
Corticosteroids (topical or absorbed) - flares
Immunomodulators
TNF-alpha antagonists (IV or SC)
Surgery – colectomy, partial SB resection, or stricturoplasty
Risk of colon cancer with IBS
Goes up over time so need to screen and do random biopsies
Yearly colonoscopy after 7-8 years with disease
High-grade dysplasia or cancer, do colectomy
Microscopic colitis
Elderly females! (70 year old lady with mild watery diarrhea)
Fairly common
Ages 50-80, female : male ~ 15:1
Autoimmune, trigger unknown
Salt and water loss in colon
Presentation = mild, chronic secretory diarrhea
Watery, non-bloody
4-10 stools per day
Minimal nocturnal or fasting symptoms
Prognosis is good; managed medically
Mild association with celiac
Diagnosis is made with biopsy
2 types of microscopic colitis
- Lymphocytic colitis
2. Collagenous colitis: thickened subepithelial collagen band
How is diagnosis made of microscopic colitis
biopsy
Ischemic colitis
90% of patients > 60 YO
Most patients have no vascular or GI dz
Fundamental insult = acute compromise in colonic bloodflow
Triggers: Vasospasm, Dehydration, hypotension, or cardiopulmonary insult (e.g. MI, PE)
Most commonly in watershed vascular areas (splenic flexure, rectosigmoid)
Presentation of ischemic colitis
Presentation = Abrupt-onset, crampy, lower abdominal pain
Urgent need to defecate
Mild diarrhea and/or hematochezia
Severe diarrhea or bleeding suggests another diagnosis
Endoscopic findings - edema, ulceration, +/- bleeding confined to a vascular region
Complete recovery within 1 – 2 weeks is typical
Infectious colitis
ACUTE Inflammatory diarrhea +/- hematochezia
Hx – short duration, travel, ill contacts, antibiotic use
Non-IBD colitis - management
Microscopic colitis – antidiarrheals (loperamide, diphenoxylate), Bismuth, topical steroids
Infectious colitis – support, +/- antibiotics
Ischemic colitis – support, antibiotics, volume support
Drug-induced – support, d/c offending drug
Radiation colitis – topical agents, endoscopic ablation
Surgery – rare; severe/refractory cases
Diverticulosis
> 50% in the elderly
Western > developing countries: increased intra-colonic pressure, Low-fiber diet
80% are asymptomatic
20% - diverticulitis, hemorrhage
Diverticular hemorrhage
5% of patients with diverticulosis
Usually from right colon
Vasa recta within the dome of diverticulum
Painless hematochezia, often heavy, typically stops w/in 2-3 days
Does NOT occur with diverticulitis
