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GI- Week 4 > Nelson: Small Intestine and Colon Pathology > Flashcards

Nelson: Small Intestine and Colon Pathology Flashcards

1
Q

Ileus

A

loss of normal propulsive function of the bowel in the absence of mechanical obstruction

o Can be associated with surgery complications, trauma, peritonitis, ischemia, meds (narcotics) infection.

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2
Q

abdominal pain, distension, vomiting lack of flatus and constipation

A

ileus

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3
Q

Hernia

A

defect in peritoneal wall allowing protrusion of serosal lined pouch of peritoneum.

o Most common in inguinal or femoral canals, umbilicus or surgical scars.

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4
Q

Visceral protrusion of bowel can lead to venous obstruction → stasis, edema, entrapment and infarct.

A

Hernia

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5
Q

Bowel adhesions

A

fibrous bands of scar tissue between bowel segments, abdominal wall or operative sites.

usually secondary to insult

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6
Q

Bowel adhesions can lead to…

A

obstruction and formation of loops through which bowel can herniate (internal hernia) and become trapped.

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7
Q

Volvulus

A

complete twisting of a loop of bowel about its mesenteric base>
leads to obstruction, vascular compromise and infarct

*can be caused by developmental abnormalities

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8
Q

What part of the intestine does volvulus usually occur in?

A

sigmoid then cecum

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9
Q

intussusception

A

segment of the bowel telescopes into the immediately distal segment>
obstruction, mesenteric blood flow compromise, infarct

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10
Q

Intussuception usually occurs in the…and is usually associated w/ ……

A

in the young

usually associated with anatomical defect in older children/adults think intraluminal tumor.

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11
Q

What is stenosis?

A

form of atresia

lumen is markedly decreased in caliber, usually associated w/ fibrous thickening of hte wall

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12
Q

What are common sites for stenosis?

A

esophagus
small bowel
anus (imperforate)

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13
Q

What is atresia?

A

incomplete development, can occur in any portion of the GI tract

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14
Q

What is an omphalocele?

A

incomplete closure of abdominal musculature, viscera herniate into ventral peritoneal sac

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15
Q

What is gastroschisis?

A

similar to omphalocele but involves all layers of abdominal wall

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16
Q

Define meckel’s diverticulum

A

true diverticulum of the small bowel composed of all three layers (mucosa, submucosa and muscularis propria)

Occurs as a result of failed involution of the VITELLINE DUCT, which connects the developing gut to the YOLK SAC.

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17
Q

What are complications associated with meckel’s diverticulum?

A 
o	Ulceration (ectopic gastric mucosa → acid production & peptic ulcers in adjacent ileum) 
o	Perforation
o	Hemorrhage
o	Fistula formation to the bladder
o	 Intussusception
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18
Q

failure to pass meconium (neonates) infants OR an older adult with obstructive constipation, abdominal distension and vomiting

A

Hirchsprung’s Disease

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19
Q

What pathological abnormality causes Hirchsprung’s Disease?

A

Normal neural crest cell migration from cecum to rectum is arrested prematurely or ganglion die> Coordinated peristalsis absent and proximal dilation occurs.

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20
Q

What are hte MC sites for Hirchsprung’s disease?

A

distal sigmoid colon and rectum

both the submucosal and myenteric plexus lacking

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21
Q

What is ischemic bowel disease?

A

mucosal ischemic injury → atrophy/loss of surface epithelium, a hemorrhagic and hyalinized lamina propria, and crypt atrophy.

Severe ischemia → transmural necrosis

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22
Q

Ischemic bowel disease tends to occur in what population?

A

Tends to occur in older individuals with coexisting cardiac or vascular disease

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23
Q

What are causes of ischemic bowel disease?

A
  1. Acute arterial obstruction/thrombosis- atherosclerosis, aortic aneurysm, hypercoagulability, thromboembolism. Typically results in transmural infarct
  2. Mesenteric venous thrombosis- hypercoagulability, portal hypertension due to cirrhosis, trauma, neoplasm and masses.
  3. Hypoperfusion- cardiac failure, shock, dehydration, vasoconstrictive drugs, vasculitis. –> Can cause ischemic damage in watershed zones.
24
Q

What bowel segments are most susceptible to ischemia?

A

Intestinal segments at the end of an arterial supply

  1. Splenic flexure (SMA/IMA watershed zone)
  2. Sigmoid colon & rectum (IMA/pudendal/iliac watershed)
25
Q

What complications are associated w/ transmural bowel necrosis?

A

Sepsis from breakdown of mucosal barrier -> septic shock and death, can occur suddenly, within hours of presentation.

  1. Acute mesenteric ischemica w/ transmural necrosis
  2. Chronic mesenteric ischemia
26
Q

What is acute mesenteric ischemia w/ transmural necrosis?

A

Severe ischemic injury → coagulative necrosis of the bowel layers (complete necrosis of all three layers in transmural infarcts)

27
Q

sudden onset abdominal pain, loss of bowel sounds, nausea vomiting, bloody diarrhea, melenic stool.

A

acute mesenteric ischemia w/ transmural necrosis

Angiography for diagnosis.

28
Q

abdominal pain following eating bouts of bloody diarrhea.

A

chronic mesenteric ischemia

can mimic inflammatory bowel disease

29
Q

What is angiodysplasia?

A

lesion of malformed submucosal and mucosal blood vessels, typically in cecum and right colon of adults.

30
Q

Lower GI bleed that can be acute, massive, chronic or intermittent.

A

angiodysplasia (20% of cases w/ lower GI bleed)

dx: colonoscopy or angiogrpahy

31
Q

Malabsorption

A

impaired absorption of nutrients (fat, carbs, protein, vitamins, electrolytes, minerals and water) caused by a disturbance of: intraluminal and brush border digestion, transepithelial transport into SI epithelium with intraepithelial processing or lymphatic transport of fats.

32
Q

What are the MC causes of malabsorption?

A

pancreatic insufficiency from chronic pancreatitis, celiac and Crohn’s

33
Q

What is hte clinical definition of diarrhea?

A

greater than 3 loose stools/day

34
Q

Acute diarrhea

A

less than 2 weeks

35
Q

chronic diarrhea

A

greater than 4 weeks

36
Q

Secretory diarrhea

A

isotonic stools

37
Q

osmotic diarrhea

A

excess osmotic forces from unabsorbed luminal solutes (lactase def)

38
Q

malabsorptive diarrhea

A

failure of global nutrient absorption and steatorrhea

39
Q

exudative diarrhea

A

inflammatory cause> bloody stools and increased neutrophils

40
Q

What are the key pathological findings of celiac’s disease?

A

o Immune mediated enteropathy triggered by ingestion of gluten containing substances.

o Immune reaction damages surface epithelium of small bowel.

41
Q

What labs do you use to dx celiacs?

A

Diagnosis based on clinical presentation, serology, and small biopsy

42
Q

Almost all celiacs carry what alleles?

A

HLA alleles

HLA-DQ2 or HLA-DQ8

43
Q

How does celiacs present clinically?

A

Classic sx of malabsorption present in infancy to mid-adulthood

  • Diarrhea, steatorrhea, weight loss, abdominal distension, iron deficiency anemia and fatigue.
  • Can also present with irritable bowel, folate or vitamin D deficiency hypocalcemia.
44
Q

What diseases are associated w/ Celiacs disease?

A

Dermatitis herpetiformis: itchy blistering autoimmune disease (IgA to gluten react to reticulin part of basement membrane)

45
Q

What is abetaliproproteinemia?

A

autosomal recessive transepithelial transport disorder

46
Q

What causes abetaliproproteinemia?

A

Mutation in microsomal triglyceride transfer protein (MTP) catalyzes lipid transport from enterocytes → monoglycerides are not assembled into chylomicrons → triacylglycerol’s accumulate in cytoplasm

47
Q

Infant that FTT, diarrhea and steatorrhea. Plasma Apo B is absent. RBC–> acanthocytes

A

Abetalipoproteinemia

48
Q

What is whipple disease?

A

systemic infection with gram positive actinomycete, Tropheryma whippelii.

49
Q

What does tropheryma whippelii cause Whipple’s disease?

A

Organism laden macrophages accumulate in lamina propria of small bowel and mesenteric lymph nodes → lymphatic obstruction.

o Can also accumulate in synovial membranes, cardiac valves, brain and other organs.

50
Q

diarrhea, weight loss, malabsorption and abdominal pain, ARTHRITIS, fever, NEURO symptoms, ENDOcarditis.

A

Whipple disease

51
Q

What is the MC type of disaccharidase def?

A

Adult onset lactase def

52
Q

What causes adult onset lactase def?

A

Lactase normally breaks lactose down into simple sugars (galactose and glucose)

o Lactase declines with age
o Lack of lactase → diarrhea, flatulence and abdominal distension upon ingestion of dairy products

53
Q

What is the MC cause of acute diarrhea?

A

Infectious diarrhea

54
Q

What are clinical findings associated w/ c.diff associated colitis?

A

Range:

mild diarrhea pseudomembranous colitis fulminant disease with perforation or toxic megacolon

55
Q

What pathological findings are associated w/ c. diff?

A

• Toxins produced → apoptosis of colonic epithelium → mucosal surface exudate of necrotic epithelium, neutrophils, mucin and fibrin.

56
Q

How do you dx c. diff?

A

detecting toxin-producing strains of C. diff with stool PCR

GI- Week 4 (12 decks)

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