Pathology of the General Intestinal Tract Flashcards

1
Q

What are the 4 common causes of intestinal obstruction?

A
  1. hernias
  2. adhesions
  3. volvulus
  4. intussusception
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2
Q

What is a hernia?

A
  • a protrusion of something through another area. WEAKNESS in the wall of the peritoneal cavity can cause a serosa lined pouch of peritoneum called a hernia sac. The sac may protrude externally, which can result in obstruction of venous outflow and enlargement of the hernia sac, making it difficult to reduce.
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3
Q

To what can an externally protruded sac (hernia) lead?

A

ENTRAPMENT (INCARCERATION), which in turn can cause arterial and venous compromise (STRANGULATION) which can cause infarction.

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4
Q

What are adhesions?

A

Acute peritoneal inflammation can lead to the formation of fibrous bridges (adhesions) between bowel segments, the abdominal wall, and operative sites. Portions of the bowel may become entrapped, leading to infarction. AKA leading to luminal or vascular compromise.

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5
Q

What are the 2 common t types of hernias?

A
  1. umbilical

2. inguinal

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6
Q

What is volvulus?

A

complete twisting of a loop of bowel around its mesenteric base of attachment. This can cause vascular and luminal obstruction.

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7
Q

** What is the most common site for volvulus to occur? (BOARD QUESTION)

A
  • SIGMOID colon, followed by the cecum, small bowel, and stomach.
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8
Q

What is Intussusception?

A
  • portion of the intestine, which is moved by a wave of peristalsis, telescopes into the immediately distal portion of bowel. PERISTALSIS propels the portion of bowel and mesentery. This may also result in vascular obstruction and subsequent infarction.
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9
Q

What tends to cause intussusception in children?

A
  • anatomic defects and may be associated with ROTAVIRUS infection.
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10
Q

What tends to cause intussusception in older children and adults?

A

an intraluminal mass

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11
Q

What may be a good treatment for children with intussusception?

A

barium enema

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12
Q

What treatment is often needed for adults with intussusception?

A

surgery

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13
Q

With what vascular supply must we be concerned in ischemic bowel disease?

A

celiac, superior mesenteric, and inferior mesenteric arteries. Acute obstruction of one of these arteries can lead to infarction of several meters of intestine.

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14
Q

What are some causes of acute obstruction?

A

atherosclerosis, aortic aneurysms, hypercoagulable states, oral contraceptives, embolization of cardiac vegetations and aortic atheromas, shock, dehydration, or vasoconstrictive drugs

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15
Q

What is the intestinal response to hypoxia?

A
  • hypoxic injury at onset of vascular compromise, minimal damage may occur if the hypoxia is TRANSIENT.
  • the most damage occurs when the blood supply is restored and the bowel undergoes REPERFUSION INJURY.
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16
Q

What is reperfusion injury?

A

release of inflammatory factors, free radical production, release of neutrophils, activation of intracellular signaling molecules, and transcription factors.

17
Q

On what does severity of ischemic bowel disease depend?

A

time frame of occlusion and the vessels affected

18
Q

What general portion of the intestines are more susceptible to ischemia?

A

intestinal portions at the END of arterial segments. Bare in mind that localized ischemia can result form generalized hypotension and hypoxia.

19
Q

Can mucosal and mural infarctions (in ischemic bowel disease) involve any level from stomach to anus?

A

YES. Often the lesions are patchy and segmental. The mucosa is hemorrhagic, ulcerated, dark red or purple, and edema thickens the bowel wall.

20
Q

What is the worst type of infarction?

A

TRANSMURAL infarction= involves substantial portions of bowel due to acute arterial occlusion. Involves entire wall of bowel (including muscularis propria and approaching the serosa).

21
Q

What site of the bowel is most susceptible to a TRANSMURAL infarction?

A

splenic flexure due to the fact that it is supplied by vessels at the end of the arterial supply. Often perforation will occur as coagulative necrosis progresses.
*Usually requires surgical resection of the necrotic portion of bowel.

22
Q

Will a mesenteric venous thrombus progress more slowly or more rapidly than an arterial thrombus?

A

more slowly

23
Q

To what may chronic ischemia in ischemic bowel disease lead?

A

fibrotic lamina propria with possible stricture formation

24
Q

How does a pt with ischemic bowel disease typically present clinically?

A

abdominal pain with guarding or rebound tenderness, vomiting, bloody stool, fever, or life threatening sepsis.

25
Q

Do mucosal and mural infarctions have a better or worse prognosis than transmural infarctions?

A

BETTER

26
Q

What may chronic ischemia in ischemic bowel disease mimic?

A

inflammatory bowel disease (IBD)

27
Q

What are some other ways ischemic bowel disease can result?

A
  • CMV= infects the endothelial cells of bowel
  • radiation enterocolitis= radiation causes vascular bowel injury.
  • necrotizing enterocolitis= acute necrosis which is often transmural. Premature and low birth weight INFANTS are at increased risk.
28
Q

** What is Angiodysplasia?

A

malformed mucosal and submucosal blood vessels. Most common in the RIGHT COLON and CECUM occurring after 6th decade of life.

29
Q

What will the bowel look like with angiodysplasia?

A

hyperemic appearance with tortuous veins, venules, and capillaries.

30
Q

** What is Meckels diverticulum?

A

persistence of vitelline duct (usually solitary diverticulum; outpouching of bowel).
*MALES more common

31
Q

What is often associated with Meckles diverticulum?

A

ectopic pancreas

32
Q

** What is colonic diverticulosis?

A

INFLAMMED blind pouch lined by mucosa that communicates with the lumen; most common in the SIGMOID colon. This may perforate causing abscess.
*more prevalent in western societies.

33
Q

How does colonic diverticulosis present clinically?

A

LLQ pain and fever.

*mimics appendicitis (but this is on the left side, not the right).

34
Q

** What is acute appendicitis?

A

neutrophilic inflammation of the appendix occurring most often in males in their 2nd-3rd decade of life. May be associated with obstruction, fecalith (aka piece of poop), gallstones, tumor, or intestinal worms.

35
Q

What are some common appendix tumors?

A
  • carcinoids (not as aggressive)
  • mucocele= dilation of appendix by mucinous secretion.
  • mucinous cystadenoma (benign)
  • mucinous cystadenocarcinoma (malignant)