LI Pathology Flashcards
1
Q
Categories of Constipation
A
- Colon Problem (Colonic Inertia - delayed colon tranit)
- Anorectal Problem (Outlet Delay - normal colon transit)
- Weak Propulsion - megarectum, pain syndromes, neuromuscular diseases
- Misdirection of Propulsion - rectocele
- IAS Relaxation Failure - Hirschsprung’s
- EAS Relaxation Failure - Dyssynergic defecation (lack of coordination b/n involuntary IAS relaxation and voluntary EAS and puborectalis muscle) - learned behavior/often in post-labor women
2
Q
Hirschsprung’s
A
- Defect in neural crest cell migration in gut –> absence of enteric NS ganglia in distal bowel (always involves IAS) –> poor relaxation/functional obstruction
- RET mutation - codes tyrosine kinase receptor in neural crest cells
- Dx - see megacolon on on barium Xray, dec tone of IAS w/ manometry and absence of ganglia on biopsy
- Tx - surgically remove aganglionic segment
3
Q
Acute Megacolon
A
- Usually in hospitalized patients few days after surgery, infection, illness (acutely - Ogilvie’s sydrome) or can be chronic
- DILATED colon on Xray
- Dec parasymp / inc symp –> dec motility/ pseudo-obstruction
- Tx
- Nothing by mouth
- Correct fluid/electrolyte imbalances that may be driving it
- Nasogastric suction
- Rectal tube decompression (w/ scope first then maybe surgical)
- Stop offending meds
- Frequent position changes
- Neostigmine (ACE inhibitor to inc available Ach - inc parasymp)
4
Q
4 Categories of Fecal Incontinence
A
1- Overflow (common) = Blockage/obstruction, fecal impaction/constipation, megarectum, blunting of rectal sensation (only liquid gets around obstruction)
- Kids, elderly, dementia pts - Dx - ab Xray or digital exam - Tx - bowel training, disimpaction (w/ finger), bowel cleansing
2- Reservoir = Dec rectal compliance (does not stretch), rectal resection/tumor, niflammatory bowel pts
- Dx - hx of constant trickle, sigmoidscopy - Tx - dec fiber in diet, treat underlying inflammation, loperamide/diphenoxylate (anti-diarrhea drugs), colostomy
3- Internal Sphincter Incontinence
- Weak IAS (trauma, degeneration, autonomic) - See dec anal tone on manometry - Hx - report mild seeping (so put cotton ball in) - Dx - middle aged to older adults, scleroderma pts, those w/ fissures - Tx - loperamide (anti-diarrheal), cotton plug
4- Idiopathic
- Middle-aged/elderly women w/ no known cause - No hx anal/rectal disease or trauma - Hx constipation/straining likely due to damage to pudendal nerve
5
Q
Acute Appendicitis
A
- Presentation - periumbilical pain 4-6 hrs –> anorexia and pain shifts to RLQ (can be atypical esp if older adults)
- Pathophysiology - often lumen obstructed by fecalith (hard, stony mass of feces) or lymph hyperplasia or carcinoid tumor –> mucus build up and bacteria can multiply in stagnant mucus
- Histo - transmural inflammation and possibly extends into surrounding fat (periappendicitis)
6
Q
Diverticular Disease
A
- Diverticula = pouch of mucosa/submucosa that herniates into muscle layer
- Likely due to low fiber western diet (requires more segmentation - weak muscles and inc abdominal pressure)
- Usually asymptomatic unless it becomes inflamed
- Complications - bleeding, perforation, fistula formation, peri-diverticular abscess
- Histo - see mucosa pouch thru muscle layer
7
Q
Ischemic Bowel Disease
A
- Can be due to vascular occlusion (emboli/thrombus) OR general hypotension/shock OR mechanical kink in vessel
- 3 Types
- Low-grade transient
- High-grade persistent
- Recurrent low-grade
- More susceptible - watershed areas (@ splenic flexure - Griffith’s pt & rectosigmoid area - Sudeck’s pt)
- Grossly - red, pseudomembranes then if chronic can see fibrosis
- Histo - upper crypt drop-out (necrosis) while lower crypts relatively preserved due to differences in blood circulation BUT total mucosal necrosis if severe
8
Q
6 Colitis Infectious Agents
A
- Enterohemorrhagic E Coli
- C Diff
- Shigella
- CMV -
- Entameba histolytica
- Cryptosporidium
9
Q
Enterohemorrhagic E Coli
A
- Adheres to lumen (adhesins) and produces Shiga toxin –>absorbed –> damages vascular endothelium of intestine as well as kidney (hemorrhagic uremic syndrome)
- O157:H7 strain produces HUS
- Source- contaminated meat or water
- Histo - infectious pattern (crypts w/ neutrophils) or ischemic pattern (edema, hemorrhage, pseudomembranes)
- Present w/ bloody diarrhea, cramps, ab pain, pseudomembranes
10
Q
C Diff
A
(“pseudomembrane colitis”)
- Usually associated w/ long-term abx use (kills normal flora to inc population of C diff)
- Gram pos bascillus that secretes toxin A (inc secretion/inflammation) and toxin B (?)
- Cramps, diarrhea, leuks in stool, fever
- Dx - suspicion and positive toxin in stool
- Gross - PSEUDOMEMBRANES (raised plaques of fibrin, RBCs, neutrophils, cell debris)
- Histo - gland drop out and necrosis (looks like ischemia); can actually see inflammatory exudate in mucosa of pseudomembranes
- Tx - discontinue abx and replace w/ metro and oral vancomycin
11
Q
Shigella
A
- Enteroinvasive (penetrates mucus layer and epithelium), gram neg, non-motile
- Watery or bloody diarrhea, cramps, fever, nausea and vomiting (esp in kids)
- Gross - friable, red, ulcerated
- Histo - apthous ulcers, acute neutrophils, crypt abscesses, early goblet depletion, edema, plasma cells
- Usually rapid recovery
12
Q
Entameba Histolytica
A
- Protozoa usually in cecum
- Bloody diarrhea, cramps,
- Contaminated food/water or fecal-oral gay sex
- Gross - small round ulcers on colonoscopy
- Histo - liquefaction, inflammation, flask-like ulcers (broad base w/ narrow neck); can find amoeba in exudate w/ round trophozoites and ingested RBCs
- Worry about spread to liver /lung - abscesses
13
Q
Cryptosporidium
A
- Esp in immune-comp
- Histo - clusters of spherical/oval blue or golden brown bodies on epithelial surface
14
Q
Microscopic Colitis (in general + 2 types)
A
- Non-infectious cause of watery diarrhea for mo-yr but normal colonoscopy (must do biopsy)
1 - Collagenous Colitis - usually middle aged/older women w/ hx abx or NSAID use
- Spontaneous remission and relapse
- Histo - thick subepithelial collagen layer stained blue w/ trichrome
2- Lymphocytic Colitis - men and women equally; associated w/ autoimmune diseases (celiac, arthritis, thyroiditis)
- Histo - inc intra-epithelial lymphocytes
15
Q
Polyps (3 Major Types
A
1- Hyperplastic - papillary tuft w/ sawtooth lumen (serrated) and large goblets; usually benign (not pre-cancerous)
2- Adenomatous -
- Pedunculated or sessile (harder to remove w/ scope)
- Histo - dysplastic nuclei (large, elongated) and dystrophic goblet cells
- Tubular and villous subtypes
- Considered pre-cancerous (villa > tubular in risk)
3- Juvenile Polyps
- Usually in distal colon (male>female) - Gross - round and pedunculated; usually mucin-filled cysts and red surface - Histo - cystic and dilated crypts; may have neutrophils or mucus; edema of lamina propria w/ lymphocytes and plasma cells
