Large Intestine Pathology Flashcards Preview

Gastrointestinal System > Large Intestine Pathology > Flashcards

Flashcards in Large Intestine Pathology Deck (19):
1

Disease

  • Failure of appropriate migration of neural crest cells during fetal development leaves a segment of rectum (and distal colon possibly) without ganglion cells
  • Both submucosal and myenteric plexuses affected
  • Distally - lacks neural stimulation/peristalsis
  • Proximally - dilated; gut has ganglion cells and thus has peristalsis
  • Associated with down syndrome

Congenital aganglionic megacolon

(Hirschsprung's disease)

2

Dx

  • Failure to pass meconium within first 24-48 hours after birth
  • DRE reveals either no stool or explosive expulsion of gas and stool
  • Proximal colon dilated (megacolon); associated with risk of perforation
  • Barium enema shows tapered transition zone

Congenital aganglionic megacolon

(Hirschsprung's disease)

3

How do you diagnose congenital aganglionic megacolon (Hirschprung's disease)?

Rectal suction biopsy

4

Treatment for congenital aganglionic megacolon (Hirschprung's disease)?

Surgical excision of aganglionic segment

5

Disease

  • Organism Trypanosoma cruzi invades and destroys ganglion cells
  • Results: Acquired aganglionosis
  • Transmitted by the bite of the Reduviid "kissing" bug

Manifestation

  • Slowly progressive constipation
  • Most cases associated with dilated esophagus (megaesophagus) as well

Chagas' disease

6

___ is the predominant mechanism (95% of cases) causing colonic ischemia. MC affects the "watershed" areas of the colon that have limited collateralization, such as the splenic flexure and rectosigmoid junction. 

Non-occlusive ischemia

7

Disease

  • Type of ischemic colitis
  • Atherosclerotic narrowing of mesenteric artery
  • MC elderly patient with severe postprandial pain (usually LUQ)
  • Loss of weight (avoids eating)

Mesenteric angina

8

Disease

  • Type of ischemic colitis
  • Due to acute vascular occlusion
    • Atrial fibrillation
    • Vascular procedures
  • Presents with severe acute abdominal pain, bloody diarrhea
  • Repair with fibrosis can lead to stricture (obstruction)

Infarct

9

  • Clinical term used to describe both lymphocytic and collagenous colitis
  • Both are characterized by
    • Chronic non-bloody diarrhea
    • Normal endoscopy
  • Differ histologically 
  • Lymphocytic colitis: M=F
  • Collagenous colitis: F>>>M

Microscopic colitis

10

Diagnosis of pseudomembranous colitis

Liquid stool used for diagnosis

  1. Enzyme immunoassay for C. difficile exotoxin A,B
  2. Identification of microbial toxin genes (never DNA-based test with higher Sn/Sp)

11

Dx

  • Profuse, watery/mucois liquid stool (may contain some blood)
  • Cramping abdominal pain
  • Fever
  • MC after antibiotic use (one day to weeks; usually a few days)

Pseudomembranous colitis

12

Particularly virulent strain of C. difficile with increased toxin production

B1/NAP1/027

13

Treatment for pseudomembranous colitis

  1. Metronidazole
  2. Vancomycin
  3. Fedaxomicin

14

Potentially lethal complication of colitis (C. difficile, IBD, ischemic, etc.) characterized by non-obstructive colonic dilation plus systemic toxicity (fever, tachycardia, leukocytosis). 

Thought to be due to release of inflammatory mediators such as NO (inhibits smooth muscle tone)

Toxic megacolon

15

Diagnosis of angiodysplasia

  1. Colonoscopy
  2. Angiography

16

With angiodysplasia, bleeding often spontaneously resolves. If it recurrent and/or if bleeding is massive, treatment options include (3):

 

  1. Endoscopic cauterization
  2. Intravascular embolization
  3. Hemicolectomy

17

  • Tortuous dilation of mucosal and submucosal vessels
  • MC in cecum/right colon

Angiodysplasia

18

  • Herniation of the mucosa and submucosa through the muscularis propria (outpouching)
  • MC sigmoid colon (highest interlumenal pressures)
  • Pathogenesis
    • Increased intraluminal pressure in combination with area of weakness where vasa recta penetrate the muscularis propria
    • Patients with CT disorders also at increased risk (e.g. Marfan syndrome, Ehlers-Danlos syndrome)

Diverticula

19