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Flashcards in Pathophysiology of Colon Deck (25):
1

Signs/sx of Ulcerative Colitis vs. Crohn's Disease

  • Both UC & Crohn's:
    • Diarrhea
    • Weight loss
    • fatigue
  • UC:
    • lower abd pain
    • hematochezia (blood in stool)
    • mucous in stool 
    • tenesmus (feeling of incomplete defecation)
  • Crohn's
    • mid or lower abd pain
    • nausea/vomiting
    • fistula sx

2

Macroscopic features: Crohn's vs. UC

  • 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

3

Pathologic/microscopic features: Crohn's vs. UC

  • 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

4

Other/associated features: Crohn's vs. UC

  • Obstruction
    • 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

5

Major types of colitis

  • microscopic colitis
  • ischemic colitis
  • infectious colitis
  • drug-induced colitis
  • radiation colitis

6

Characteristics of microscopic colitis

  • subtypes:
    • lymphocytic
      • lymph infiltration of mucosa/SM
    • collagenous
      • thickened collagenous band
  • mild association w/celiac disease
  • good prognosis

7

Characteristics of ischemic colitis

  • elderly pt.s, often w/out vascular or GI disease
  • triggers:
    • vasospasm
    • dehydration, hypotension, cardiopulmonary insult
  • commonly @ "watershed" vascular areas
    • splenic flexure
    • rectosigmoid

8

Clinical presentation of ischemic colitis

  • = 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

9

Characteristics of infectious colitis

  • Inflammatory diarrhea +/- hematochezia
    • Mucosal invasion
    • Toxin-related injury
  • Hx:
    • short duration
    • travel
    • ill contacts/exposures
    • antibiotic use
       

10

Exposures ==> infectious colitis

  • Undercooked beef
    • E. Coli
  • Contaminated poultry, eggs, milk, lettuce
    • Salmonella/Shigella, Campylobacter, Yersinia
  • Antibiotic use, hospitalization
    • C. Difficile
  • Anal intercourse
    • Venereal proctitis
       

11

Characteristics of diverticulosis (general)

  • outpouchings of colon wall
    • composed of mucosa and submucosal layer through muscularis propria
    • contain by serosa
  • diverticula form and grow
  • common in western countries
    • low-fiber diet = risk factor
  • benign condition in most (80%) of pts
  • complications (20-25%)
    • infection
    • perforation
    • abscess formation
    • hemorrhage

12

Causes of acute diverticulutis

  • large stool or food particle lodges @ diverticulum ==> impacted @ diverticulum
  • if impaction is not relieved ==> bacteria multiply, expand, form gas ==> rupture of diverticulum

13

Types & sx of acute diverticulutis

  • uncomplicated
    • abscess contained @ colon wall
  • complicated
    • free perforation
    • large abscess
    • bowel obstruction
  • sigmoid diverticula = most common
  • sx:
    • LLQ pain
    • fever
    • nausea/vomiting

14

Characteristics of complications of diverticular disease

  • large abscess formation
  • perforation ==> peritonitis
  • diverticular hemorrhage
    • mucosa of diverticulum erodes into penetrating vasa recta ==> intraluminal bleeding

15

General characteristics of lower GI bleeding

  • Bleeding distal to ligament of Treitz
  • Colonic bleeding >>> small bowel bleeding
  • Usually presents as hematochezia = blood in stool
    • Less commonly, melena
       

16

Common etiologies of LGIB

  • •Diverticulosis
  • •Arteriovenous malformations
  • •Colitis
  • •Neoplasm
  • •Radiation colitis
  • •Post-polypectomy or biopsy
  • •Miscellaneous
    • •Internal hemorrhoids
    • •Solitary rectal ulcer
    • •Anal fissure
    • •Dieulafoy’s lesions
       

17

LGIB: DDx of Abdominal pain or diarrhea 

  • ischemic colitis
  • IBD

18

LGIB: DDx of weight loss, new constipation, anemia

  • neoplasm

19

  • LGIB: DDx of
    • sudden onset heavy bleed + sudden cessation
    • eldery pt

  • diverticulosis

20

  • LGIB: DDx of 
    • acute dysentery
    • travel
    • ill contacts
    • antibiotic use

  • infectious diarrhea

21

LGIB: DDx of microcytic anemia

  • neoplasm
  • AVM (arteriovenous malformation)

22

LGIB: DDx of NSAID use

  • drug-induced colitis

23

LGIB: DDx of hx of pelvic radiation

  • XRT proctitis

24

Causes & presentation/dx of colon obstruction

  • Sx:
    • N/V
    • abd. distension
    • constipation or obstipation
  • Dx:
    • Xray = tentative dx
    • CT confirms
  • Causes
    • Malignancy
    • Benign – adhesions, strictures, volvulus
    • Foreign body – inserted or ingested
       

25

Dx of lower GI bleed

  • usually via colonoscopy