Chapter 17 Part 4

Question 1

Which part of the GI tract is most often involved in obstruction and why?

Answer 1

• small intestine

- narrow lumen

Question 2

Name the most common causes of mechanical obstructions.

Answer 2

• hernias
• adhesions
• intussusception
• volvulus

Question 3

What is “incarceration” of the bowels?

Answer 3

• in a herniation, when venous drainage is impaired creating stasis, edema, and increasing bulk of the loop
• bowel becomes permanently entrapped

Question 4

What is “strangulation” of the bowels?

Answer 4

• arterial and venous compromise of the entrapped loop of bowel
• leads to infarction

Question 5

What is the most common cause of intestinal obstruction in the U.S.?

Answer 5

-internal herniations due to adhesions

Question 6

True or False: volvulus results in both luminal and vascular compromise

Answer 6

True; thus it displays characteristics of both obstruction and infarction

Question 7

What is the most common cause of intestinal obstruction in children younger than 2yrs?

Answer 7

intussusception

-a segment of intestine, constricted by a wave of peristalsis, telescopes into the immediately distal segment

Question 8

What can be used as both a diagnostic and therapeutic approach to idiopathic intussusception in infants and young children?

Answer 8

-contrast enemas

air enemas may also be effective to reduce intussusception, but surgery is req’d for older kids and adults

Question 9

What are the three main factors that affect the severity of ischemic bowel disease?

Answer 9

1) severity of vascular compromise
2) time frame during which it develops
3) which vessels are affected

Two punches: hypoxic injury, then reperfusion injury

Question 10

Which two areas of the bowel are more susceptible to ischemic bowel disease and why?

Answer 10

• splenic flexure
• rectosigmoid colon

–they are in watershed zones of arterial supply

Question 11

Occlusion of which artery supplying the bowels has the worse outcome and why?

Answer 11

-superior mesenteric A. b/c it supplies all of the small intestines and the proximal part of the large intestines

Question 12

What are some causes of acute obstruction of blood flow to the arteries that supply the GI tract?

Answer 12

• severe atherosclerosis, which is common at arterial bifurcations due to increased turbulence
• hypercoagulable states (APS, Factor V, smoking, etc.)

Question 13

What are some causes of chronic obstruction of blood flow to the arteries that supply the GI tract?

Answer 13

• cardiac failure leads to chronic hypoperfusion

- vasoconstriction due to drugs like cocaine

Question 14

What is the initial appearance of an infarcted segment of bowel?

Answer 14

-intensely congested, dusky purple/red; sharp demarcation between healthy bowel and sick bowel

(later on, the intestinal wall becomes edematous, thick, and rubbery)

Question 15

What category of necrosis happens in the bowels?

Answer 15

coagulative necrosis

Question 16

What sex and age group is more commonly affected by ischemic bowel disease?

Answer 16

women over the age of 70yrs

Question 17

What is the clinical presentation of acute ischemic bowel disease?

Answer 17

-sudden onset of cramping in the LLQ, desire to defecate, passage of blood or bloody diarrhea

Question 18

What are the characteristics of angiodysplasia?

Answer 18

• malformed mucosal/submucosal vessels that are dilated and have thin walls
• more common in the cecum and ascending colon after the 6th decade of life

Question 19

True or False: while angiodysplasia is present in only 1% of adults, it accounts for 20% of major episodes of lower intestinal bleeding in the elderly

Answer 19

True.