Diseases of the Colon Flashcards
Right colon func, transverse/desc/sig func
r: absorb ions, water
transverse/descending/sigmoid: store waste and indigestible materials
other: bacterial fermentation of nonabsorbed nutrients; elimination of waste and indig materials
Gold standard of IBD dx
Direct visualization and biopsy
when:
sx >2 wks (diarrhea, crampy abd pain, bleeding)
Neg work up for other causes
Extra-intest sx
IBD types
UC
Crohn’s
UC signs/sx
diarrhea
weight loss
fatigue
LOWER abd pain
hematochezia (bright red blood in stool)
mucus in stool
tenesmuc
Crohn’s signs/sx
diarrhea
weight loss
fatigue
Mid or lower abd pain
N/v
fistula sx
Macroscopic features of Crohn's vs UC bowel region fistulae or abscess strictures distribution
*pics 10/19
Bowel region:
Crohn’s: entire GI tract
UC: colon
Fistulae or abscess:
Crohn’s yes
UC no
strictures:
Crohn’s: common
UC: no
Distribution:
Crohn’s: skip lesions
UC: diffuse
UC= “hamburger meat appearance”; pseudopolyps
Pathologic features of Crohns vs UC inflammation ulcers fibrosis granulomas
Inflammation:
Crohn’s: transmural
UC: mucosa +/- SM
Ulcers:
Crohn’s: deep, linear
UC: superficial, confluent
Fibrosis:
Crohn’s: marked
UC: mild to none
Granulomas:
Crohn’s: yes ~20%
UC: no
Crohn's vs UC obstructive malabsorption malignant potential recurrence after colectomy toxic megacolon
Obstructive:
Crohn’s: yes
UC: no
Malabsorption:
Crohn’s: yes
UC: no
Malignant potential:
Crohn’s: with colonic involvement
UC: yes
recurrence after colectomy:
Crohn’s: common
UC: no
toxic megacolon
Crohn’s: no
UC: yes
Types of Crohn’s fistulas
Entero-cutaneous Entero-enteral Entero-gastric Entero-vesical Entero-vaginal
Extraintestinal manifestations
mostly 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
5-aminosalicylates, PO or PR (Sulfasalazine, olsalazine, mesalamine, balsalazide)
Immunomodulators
(6-mercaptopurine, Azathioprine, Methotrexate)
TNF-alpha antagonists (IV or SC)
(Infliximab, Adalimumab, Natalizumab)
Surgery – colectomy, partial SB resection, or stricturoplasty (Refractory disease, obstruction, fistula, HG dysplasia, or cancer)
Colon cancer surveillance and IBD
- risk increases w/ duration
- yearly colonoscopy after 7-8 yrs
- bx from every segment
- LG dysplasia is common in IBD
- HG dysplasia or cancer–> colectomy
Microscopic colitis
2-5 per 100,000 indiv
- 50-80y, F:M 15:1
- autoimmune, trigger unknown
- salt and water loss in colon
Presentation= chronic secretory diarrhea
- watery, nonbloody
- 4-10 per day
- minimal nocturnal or fasting sx
2 subtypes (hist)
lymphocytic colitis
collagenous colitis
Mild assoc w/ celiac
good prognosis (no increased cancer risk, etc)
Dx of microscopic colitis
biopsy (bc colonoscopy is usually normal)
LC: lymphocytic infiltration of mucosa and SM
CC: thickened subepi collagenous band
Ischemic colitis
90% >60 y -most w/o vascular or GI disease -acute compromise in colonic blood flow -triggers: vasospasm dehydration, hypotension, cardiopulm insult (MI, PE)
Most common areas of ischemic colitis
Watershed vascular areas:
splenic flexure
rectosigmoid
Presentation of ischemic colitis
Abrupt-onset, crampy, lower abdominal pain
Urgent need to defecate
Mild diarrhea and/or hematochezia
(Severe diarrhea or bleeding– diff dx)
Endoscopic findings - edema, ulceration, +/- bleeding confined to a vascular region
Complete recovery usually in 1-2 weeks
Less common causes:
Vasculitis – Lupus (SLE), Polyarteritis Nodosa (PAN), Henoch-Schonlein
Substance abuse - cocaine, amphetamines
Medications - estrogens, migraine medications
Mesenteric thrombosis - Protein C/S deficiency, Factor V Leiden def., etc.
Rare: Marathon running, extreme dehydration
Infectious colitis
-inflammatory diarrhea +/- hematochezia (mucosal invasion; toxin related injury)
Hx: short duration, travel, ill contacts, abx use
Ex: pseudomembranes seen w/ C. diff
Undercooked beef: E. coli
Poultry, eggs, milk, lettuce: salmonella/shigella, campylobacter, yersinia
Abx use/hosp: C. diff
Anal intercourse: venereal proctitis
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 (increased intracolonic, pressure, low fiber)
80% asymptomatic
20% diverticulitis, hemorrhage
(endoscopy shows large “holes”)
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
Acute diverticulitis
10-15% of patients w/ diverticula
Fecolith obstructs diverticulum:
Distension from bacterial gas and neutrophils
Microperforation, abscess
Macroperforation with peritonitis
Sx: LLQ pain, nausea, fever
Management of diverticulitis
Diagnosis: CT or MRI
Tx: oral or IV abx; abscess drainage; surgery
Strictures may require dilation or resection
Lower GI bleeding
Bleeding distal to ligament of Treitz
colonic bleeding»_space;> SB bleeding
Usually hematochezia, less commonly melena
Mort: 1-2%
(UGI bleed higher)
Ceases w/o intervention in most
Recurs freq w/o cause ID
