Robbins GI intestines, colon, rectum

Question 1

Intestinal Obstruction: name them

Answer 1

80%: hernias, intestinal adhesions, intussusception, and volvulus 1-0-15%: tumors, infarction, and other causes of strictures, for example, Crohn disease

Question 2

clinical manifestations of intestinal obstruction include

Answer 2

abdominal pain and distention, vomiting, and constipation.

Question 3

Hernias: Acquired

Answer 3

1. Acquired hernias typically occur anteriorly, via the inguinal and femoral canals, umbilicus, or at sites of surgical scars, and are common, occurring in up to 5% of the population
2. Obstruction usually occurs because of visceral protrusion (external herniation) and most frequently-associated with inguinal hernias, which tend to have narrow orifices and large sacs.
3. Small bowel loops typically, but omentum + large bowel may also protrude –> entrapped
4. Resultant stasis + edema –> permanent entrapment (incarceration) —> arterial/venous compromise (strangulation)—> infarction

Question 5

Frequency of hernias, adhesions, volvulus

Answer 5

1. Hernias are the most frequent cause of intestinal obstruction worldwide and the third most common cause of obstruction in the U.S.
2. adhesions are the most common cause of intestinal obstruction in the United States.
3. it is rare, volvulus can be overlooked clinically.

Question 6

Ischemic Bowel Disease: acute arterial obstruction

Answer 6

1. severe atherosclerosis (which is often prominent at the origin of mesenteric vessels)
2. aortic aneurysm
3. hypercoagulable states
4. oral contraceptive use
5. embolization of cardiac vegetations or aortic atheromas

Question 7

Ischemic Bowel Disease: Intestinal hypoperfusion

Answer 7

1. associated with
2. cardiac failure
3. shock
4. dehydration
5. vasoconstrictive drugs.

Question 8

Ischemic Bowel Disease: Systemic vasculitides

Answer 8

1. polyarteritis nodosa
2. Henoch-Schönlein purpura
3. granulomatosis with polyangiitis (Wegener granulomatosis),

Question 9

Ischemic Bowel Disease: Mesenteric venous thrombosis

Answer 9

1. uncommon but can result from
2. inherited or acquired hypercoagulable states
3. invasive neoplasms
4. cirrhosis
5. trauma
6. abdominal masses that compress the portal drainage.

Question 10

watershed zones

Answer 10

the splenic flexure: the superior and inferior mesenteric arterial circulations terminate

the sigmoid colon (lesser than splenic flexure): rectum where inferior mesenteric, pudendal, and iliac arterial circulations end

Generalized hypotension or hypoxemia can therefore cause localized injury, and ischemic disease should be considered in the differential diagnosis of focal colitis of the splenic flexure or rectosigmoid colon.

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Intestinal capillaries run alongside the glands, from crypt to surface, before making a hairpin turn to empty into the post-capillary venules. This arrangement makes the surface epithelium particularly vulnerable to ischemic injury, relative to the crypts. Organization of the blood supply in this patterns has advantages, as it protects the epithelial stem cells, which are located within the crypts and are necessary for recovery from epithelial injury. This pattern of surface epithelial atrophy, or even necrosis and sloughing, with normal or hyperproliferative crypts is a morphologic signature of ischemic intestinal disease.

Question 11

Mucosal and mural infarctions

Answer 11

1. may progress to more extensive infarction if the vascular supply is not restored
2. diagnosis of nonocclusive ischemic enteritis and colitis difficult:
   
   1. nonspecific abdominal symptoms
      
      1. intermittent bloody diarrhea
      2. intestinal obstruction.

Question 12

appears as an inflammatory bowel disease with episodes of bloody diarrhea interspersed with periods of healing.

Answer 12

Chronic ischemia

Question 13

intranuclear basophilic inclusions s

Answer 13

1. CMV causes focal necrosis with minimal inflammation in virtually any organ.
2. intestinal necrosis and ulceration can develop and be extensive, leading to the formation of pseudomembranes and debilitating diarrhea.
3. Especially common in the immunocompromised
4. Diagnosis of CMV infections is made by demonstration of characteristic morphologic alterations in tissue sections, viral culture, rising antiviral

Question 14

Radiation enterocolitis

Answer 14

1. one indicator: the presence of highly atypical “radiation fibroblasts” within stroma
2. Acute radiation enteritis manifests as
   
   1. anorexia, abdominal cramps, malabsorptive diarrhea
3. Chronic radiation enteritis or colitis is often more indolent and may present as an inflammatory entero colitis

Question 15

Necrotizing enterocolitis (NEC)

Answer 15

1. most common acquired GI emergency of neonates (especially premature babies, low birth weight babies)
2. acute disorder of small and large intestines
3. can result in trans­mural necrosis
4. most common acquired GI emergency of neonates, particularly those who are premature or of low birth weight, and frequently presents when oral feeding is initiated.

Question 16

Angiodysplasia

Answer 16

1. a lesion characterized by malformed submucosal and mucosal blood vessels
2. occurs most often in: cecum or right colon
3. usually presents after the sixth decade of life.
4. angiodysplasia: less than 1% of adult population; accounts for 20% of major episodes of lower intestinal bleeding
5. hemorraging: may be chronic+intermittent, acute and massive.
   6.