GI goljan vascular disorders, sigmoid diverticular, IBS

Question 1

which part of bowel is more likely to have ischemic damage?

Answer 1

small bowel

Question 2

What areas are supplied by SMA?

Answer 2

most of small bowel;
ascending and transverse colon;
overlap w/ IMA at splenic flexure

Question 3

Where is a watershed area?

Answer 3

splenic flexure

Question 4

What are the types of infarctions assoc w/ vascular disorders?

Answer 4

transmural;

mural and mucosal infarctions

Question 5

Define transmural bowel infarction. what is the most common cause?

Answer 5

full thickness hemorrhagic infarction usually involving all or part of small bowel due to OCCLUSION OF SMA

Question 6

When is mural and mucosal infarctions likely to occur?

Answer 6

hypoperfusion states (shock)

Question 7

What are causes of acute ischemia involving small bowel?

Answer 7

acute mesenteric ischemia (50%);
nonocclusive ischemia (25%);
mesenteric vein thrombosis (25%)

Question 8

What is the mechanism of acute mesenteric ischemia?

Answer 8

embolism from L side of heart to SMA;

thrombosis of SMA

Question 9

Embolism from left heart to SMA causes what?

Answer 9

atrial fibrillation is most common predisposing arrhythmia

Question 10

What are characteristics of nonocclusive ischemia?

Answer 10

Hypotension secondary to heart failure (common);
Hypovolemic shock;
patient taking digitalis (possible vasospasm)

Question 11

What does mesenteric vein thrombosis lead to?

Answer 11

thrombosis states => polycythemia vera; anti-phospholipid syndrome;
extension of renal cell carcinoma into vena cava

Question 12

What are clinical findings of small bowel infarction

Answer 12

sudden onset of diffuse abdominal pain;
bowel distention;
bloody diarrhea; 
absent bowel sounds (ileus);
No rebound tenderness (peritonitis) early in infarction

Question 13

What are micro and physical exam findings?

Answer 13

profound neutrophilic leukocytosis

positive stool guaiac

Question 14

Radiographic findings in small bowel infarction

Answer 14

“thumbprint sign” due to edema in bowel wall;
bowel distention w/ air-fluid levels similar to bowel obstruction;
abdominal CT is 90% sensitive

Question 15

Tx for small bowel infarction

Answer 15

surgery for embolic disease; 
thrombotic disease (anticoag and surgery)

Question 16

What does ischemic colitis involve?

Answer 16

splenic flexure of large bowel => watershed area

Question 17

What has occurred when severe pain occurring in splenic flexure shortly after eating?

Answer 17

ischemic colitis => atherosclerotic narrowing of SMA causing mesenteric angina

Question 18

What are clinical findings in ischemic colitis?

Answer 18

Hx compatible w/ mesenteric angina;
pain localized to splenic flexure;
barium study shows “thumb-printing” of colonic mucosa (edema of mucosa)

Question 19

What accompanies pain localized to splenic flexure in ischemic colitis?

Answer 19

bloody diarrhea due to mucosal or mural infarction

Question 20

What may ischemic colitis lead to and why?

Answer 20

normal repair of infarction results in fibrosis => ischemic strictures and obstruction

Question 21

Define angiodysplasia

Answer 21

dilation of mucosal and submucosal venules in cecum and right colon;
increased wall stress in cecum stretches venules

Question 22

Who is most at risk for angiodysplasia?

Answer 22

elderly => vascular ectasias in cecum increases w/ age

Question 23

clinical findings of angiodysplasia

Answer 23

hematochezia;

association w/ vWf disease and calcific aortic stenosis

Question 24

how is angiodysplasia Dx?

Answer 24

colonoscopy and angiography

Question 25

Tx for angiodysplasia

Answer 25

colonoscopy; angiography localizes disease; Right hemicolectomy; correction of aortic stenosis

Question 26

Epidemiology of sigmoid colon diverticular disease

Answer 26

incidence in general public is 35-50%; incidence increases w/ age; common site for diverticula is entire GI tract

Question 27

Pathogenesis of sigmoid colon diverticular disease

Answer 27

low-fiber diet w/ increased constipation; | area of weakness is where vasa recta penetrate muscular propria

Question 28

most common site for sigmoid colon diverticular disease

Answer 28

sigmoid colon

Question 29

where does diverticulum in sigmoid colon diverticular disease occur?

Answer 29

juxtaposed to a blood vessel

Question 30

what are some associations w/ sigmoid colon diverticular disease?

Answer 30

Marfan syndrome; Ehlers-Danlos syndrome; adult polycystic kidney disease

Question 31

Define 2 outcomes of sigmoid colon diverticular disease

Answer 31

diverticulitis (most common)=> fecalith in diverticulum sac produces ulceration and ischemia diverticulosis=> painless bleeding and often massive (hematochezia)

Question 32

Clinical findings w/ diverticulitis

Answer 32

fever; diarrhea initially followed by constipation; left lower quandrant pain ("L sided appendicitis"); tender mass can be easily palpated

Question 33

How is diverticulitis Dx?

Answer 33

CT scan or water-soluble barium study

Question 34

what is risk in diverticulitis?

Answer 34

increased risk for perforation and abscess formation

Question 35

Will hematochezia be a problem in healed diverticulitis?

Answer 35

No=> scarring will prevent bleeding

Question 36

What is the most common cause of fistulas of the bowel? (connection bw hollow structures)

Answer 36

sigmoid colon diverticular disease

Question 37

What is a common fistula in GI tract? what is it associated with?

Answer 37

colovesical fistula; | associated w/ pneumaturia (air in urine) and recurrent UTI

Question 38

Nonpharm and pharm Tx of sigmoid colon diverticular disease

Answer 38

increase fiber in diet to prevent constipation; | ABx for acute disease

Question 39

When is colonic resection necessary in sigmoid colon diverticular disease?

Answer 39

repeated episodes of diverticulitis and bleeding that does not stop; abscess and fistula formation; obstruction

Question 40

Irritable bowel syndrome is caused by what? what are mechanisms of this loss?

Answer 40

intrinsic colonic motility disorder; possible loss of tolerance to GI flora; possible genetic factors; environmental triggers

Question 41

Who is most likely to have IBS? How common is IBS?

Answer 41

females > males; | most common functional bowel disorder

Question 42

Risk factors for IBS

Answer 42

Hx of childhood sexual abuse; domestic abuse in women; increased stress, depression, personality disorder

Question 43

How does IBS typically present?

Answer 43

alternating bouts of diarrhea and constipation

Question 44

What are 3 characteristics of alternating bouts of diarrhea and constipation in IBS?

Answer 44

abdominal pain and bloating relieved by defecation; stools accompanied by mucus; abnormal defecation=> strain, sense of incomplete evacuation

Question 45

How is IBS diagnosed?

Answer 45

normal flexible sigmoidoscopy or colonoscopy

Question 46

Nonpharm Tx of IBS

Answer 46

mainstay is adequate fiber intake; | eliminate foods that aggravate (coffee, fatty foods, diary)

Question 47

pharm Tx of IBS

Answer 47

antispasmodics-anticholinergics (dicylomine); Loperamide effective for diarrhea (serotonin type 3 receptor antagonist); Lubiprostone (Cl-channel activator) effective for constipation; Rifaximin is effective if small bowel bacterial overgrowth