S2: Ch 3 GI 1-2

1. Bowel obstruction
2. Abscess
3. Fistulas
b. Abscess formation (can be drained either percutaneously under CT guidance or surgically).
c. Colovesical fistula- accounts for 50% of fistulas secondary to diverticulitis; 50% close to spontaneously.
d. Obstruction- due to chronic inflammation and thickening of bowel wall.
e. Free colonic perforation- uncommon but catastrophic (leads to peritonitis).

a. About 30%. Usually w/in the first 5 years.

a. Diverticulosis: Barium enema
b. Diverticulitis: CT scan (barium enema and colonoscopy are contraindicated).

a. When feces become impacted in the diverticulum, leading to erosion and micro-perforation.

1. Fever
2. LLQ pain
3. Leukocytosis.
b. Other possible features: alteration in bowel habits (constipation or diarrhea), vomiting, and sometimes a painful mass on rectal exam if inflammation is near the rectum.

a. CT scan (abdomen and pelvis) w/oral and VI contrast is the test of choice.
i. It may reveal a swollen, edematous bowel wall or abscess.
b. Abdominal radiographs help in excluding other potential causes of LLQ pain and can rule out ileus or obstruction (indicated by air-fluid levels, distention, and perfusion (indicated by free air).
c. Barium enema and colonoscopy are contraindicated in acute diverticulitis due to risk of perforation!

a. Initial episode IV abx, bowel rest (NPO), IV fluids.
i. Mild episodes can be tx’d on outpatient basis if pt is reliable and has no comorbid conditions.
ii. If sx persist after 3-4 days, surgery may be necessary.
b. Second and subsequent episodes- Surgery is recommended (resection of involved segment) once acute inflammation resolves.
c. Low-residue diet (e.g., no nuts, seeds).

a. Tortuous, dilated veins in submucosa of the colon (usually proximal) wall.
b. A common cause of lower GI bleeding in pts >60.
c. Bleeding is usually low grade, but 15% of pts may have massive haemorrhage if veins rupture.
d. Diagnosed by colonoscopy (preferred over angiography)

e. In about 90% of pts, bleeding stops spontaneously.

f. It can frequently be treated by colonoscopic coagulation of the lesion.

g. If bleeding persists, a right hemicolectomy should be considered.

a. SMA.
b. Most commonly embolism (50% of cases).

1. Arterial embolism
2. Arterial thrombosis
3. Non-occlusive mesenteric ischaemia
4. Venous thrombosis

a. Cardiac (e.g., atrial fibrillation, MI, valvular disease).

a. Thrombosis (25%).

a. Most have atherosclerotic disease (e.g., CAD, PVD, stroke) at other sites.
b. Acute occlusion occurs over pre-existing atherosclerotic disease. The acute event may be due to a decrease in cardiac output (e.g., resulting from MI, CHF) or plaque rupture.
c. Collateral circulation has usually developed

a. Splanchnic vasoconstriction secondary to low cardiac output.
b. Typically seen in critically ill elderly pts.

a. Infection
b. Hypercoagulable
c. States
d. Oral contraceptives
e. Portal HTN
f. Malignancy
g. Pancreatitis

a. 60-70%.
b. If bowel infarction has occurred, the mortality rate can exceed 90%.

a. Acute is much more common than chronic

a. Pre-existing heart disease (e.g., CHF, CAD).

a. Sx are more sudden and painful than other causes.

a. Sx are more gradual and less severe than embolic.

a. Typically occurs in critically ill pts.

a. Sx may be present for several days or even wks, w/gradual worsening.

a. Classic presentation is acute onset of severe abdominal pain disproportionate to physical findings. Pain is due to ischaemia and possibly infarction of intestines, analogous to MI in CAD.
b. Anorexia, vomiting
c. GI bleeding (mild)
d. Peritonitis, sepsis, and shock may be present in advanced disease.

a. The abdominal exam may appear benign even when there is severe ischaemia. This can lead to a delay in dx.
b. The acuteness and severity of pain vary depending on the type of acute mesenteric ischaemia.

a. Mesenteric angiography is the definitive diagnostic test!!!
b. Obtain a plain film of the abdomen to exclude the causes of abd pain.
c. “Thumbprinting on barium enema due to thickened edematous mucosal folds.

a. Supportive measures: IV fluids and broad-spectrum abx.
b. Direct intra-arterial infusion of PAPAVERINE (vasodilator) into the superior mesenteric system during arteriography is the therapy of choice for all arterial causes of acute mesenteric ischaemia. This relieves occlusion and vasospasm.
c. Direct intra-arterial infusion of thrombolytics or embolectomy may be indicated in some pts w/embolic acute mesenteric ischaemia.

a. Heparin!

89. Note: surgery (resection of nonviable bowel) may be needed in all types of acute mesenteric ischaemia if signs of peritonitis develop.

1. Hypotension
2. Tachypnea
3. Lactic acidosis
4. Fever
5. Altered mental status (eventually leading to shock).
6. Check the lactate level if acute mesenteric ischaemia is suspected!!!

a. Vasopressors.