Pathology of the General Intestinal Tract

Question 1

What are the 4 common causes of intestinal obstruction?

Answer 1

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

Question 2

What is a hernia?

Answer 2

• 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.

Question 3

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

Answer 3

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

Question 4

What are adhesions?

Answer 4

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.

Question 5

What are the 2 common t types of hernias?

Answer 5

1. umbilical

2. inguinal

Question 6

What is volvulus?

Answer 6

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

Question 7

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

Answer 7

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

Question 8

What is Intussusception?

Answer 8

• 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.

Question 9

What tends to cause intussusception in children?

Answer 9

• anatomic defects and may be associated with ROTAVIRUS infection.

Question 10

What tends to cause intussusception in older children and adults?

Answer 10

an intraluminal mass

Question 11

What may be a good treatment for children with intussusception?

Answer 11

barium enema

Question 12

What treatment is often needed for adults with intussusception?

Answer 12

surgery

Question 13

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

Answer 13

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

Question 14

What are some causes of acute obstruction?

Answer 14

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

Question 15

What is the intestinal response to hypoxia?

Answer 15

• 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.

Question 16

What is reperfusion injury?

Answer 16

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

Question 17

On what does severity of ischemic bowel disease depend?

Answer 17

time frame of occlusion and the vessels affected

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

What is the worst type of infarction?

Answer 20

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

Question 21

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

Answer 21

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.

Question 22

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

Answer 22

more slowly

Question 23

To what may chronic ischemia in ischemic bowel disease lead?

Answer 23

fibrotic lamina propria with possible stricture formation

Question 24

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

Answer 24

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

Question 25

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

Answer 25

BETTER

Question 26

What may chronic ischemia in ischemic bowel disease mimic?

Answer 26

inflammatory bowel disease (IBD)

Question 27

What are some other ways ischemic bowel disease can result?

Answer 27

• 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.

Question 28

** What is Angiodysplasia?

Answer 28

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

Question 29

What will the bowel look like with angiodysplasia?

Answer 29

hyperemic appearance with tortuous veins, venules, and capillaries.

Question 30

** What is Meckels diverticulum?

Answer 30

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

Question 31

What is often associated with Meckles diverticulum?

Answer 31

ectopic pancreas

Question 32

** What is colonic diverticulosis?

Answer 32

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.

Question 33

How does colonic diverticulosis present clinically?

Answer 33

LLQ pain and fever.

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

Question 34

** What is acute appendicitis?

Answer 34

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.

Question 35

What are some common appendix tumors?

Answer 35

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