A. Types

1. Acute Mesenteric Ischemia
   1. Non-occlusive
   2. Arterial embolism / thrombosis
   3. Venous thrombosis
   4. Focal segmental thrombosis
2. Chronic Mesenteric Ischemia
   1. Reversible: "Abdominal Angina"
   2. Ulcerative
   3. Colonic stricture
   4. Colonic gangrene
   5. Fulminant Ischemic Colitis
   6. Venous thrombosis

B. Causes

1. Arterial Obstruction
   1. Hypercoagulability
   2. Vascular Disease
2. Hypercoagulability
   1. Malignancy
   2. Collagen vascular Disease
   3. Inherited hypercoagulable state
   4. Microangiopathic hemolytic anemia (TTP/HUS)
   5. Sepsis (Disseminated Intravascular Coagulopathy)
3. Vascular Disease
   1. Atherosclerotic Vascular Disease
   2. Diabetes
   3. Collagen vascular disease
   4. Fibromuscular Dysplasia (FMD) of mesenteric arteries [1,2]
4. Venous Stasis [4]
   1. Portal Hypertension
   2. Venous thrombosis [5]
   3. Congestive Heart Failure

C. Symptoms and Signs

1. Mid abdominal pain after eating
2. Abrupt onset of extreme abdominal pain [3]
3. May progress to malabsorption and even weight loss [6]
4. Gastric or small intestinal ulcerations may occur
5. Pain in abdomen during physical examination
6. Hemoccult positive stool
7. Mesenteric venous thrombosis may present with acute, subacute, or chronic symptoms [5]

D. Laboratory and Radiographic Findings

1. Leukocytosis >15K ~75%
2. Metabolic Acidosis ~50%
3. Increased serum amylase, alkaline phosphatase, LDH, and serum inorganic phosphate
4. Increased hematocrit (due to dehydration)
5. Vascular calcifications commonly seen on radiographic studies
6. Computerized tomography is often very helpful
7. Ultrasonography or Magnetic Resonance Angiography are being developed
8. Invasive Angiography
   1. Often required to confirm diagnosis involving small intestine
   2. Ischemic colitis due to low flow state diagnosed with flexible sigmoidoscopy
9. Air-fluid levels are commonly seen

E. Treatment

1. Correct underlying problem
2. Nothing given orally (NPO), Place Nasogastric (NG) Tube
3. Correct fluid deficits
4. Broad spectrum parenteral antibiotics (Ampicillin/Gentamicin/Metro or Cefoxitin / Metro)
5. Early angiogram
6. Exploratory surgery to remove infarcted / gangrenous bowel
7. Consider anti-coagulation therapy 48 hours post-operation
8. Anticoagulation alone can be used with mesenteric venous thrombosis without infarction [6]

F. Chronic Ischemia Prophylaxis

1. Often in patients with evidence of atherosclerotic disease
2. Coronary artery and Cerebrovascular disease most common
3. Systemic vasodilators may be useful, but hypotension must be avoided
4. Unclear if low ("renal") dose dopamine is helpful though it does cause splanchnic dilation

1. 90% of patients are >60 years
2. Usually acute precipitating cause
3. Predisposing Lesion 20%
   1. Colon CA
   2. Stricture
   3. Diverticulum
   4. Fecal Impaction
4. Most often occurs in Splenic flecture ("Watershed Zone")

B. Symptoms and Signs

1. Bloody Diarrhea
2. Constipation
3. Pain, usually out of proportion to exam, usually left upper quadrant

C. Diagnosis

1. Colonoscopy
2. Gastrograffin enema

D. Treatment

1. As above
2. Surgical Resecation may be required

References

1. Moncure AC and Rashid A. 1995. NEJM. 332(12):804 (Case Record)
2. Stokes JB, Bonsib SM, McBride JW. 1996. Arch Intern Med. 156(22):2611
3. Gertler JP and Keel SB. 1997. NEJM. 336(8):567 (Case Record)
4. Brandt LJ and Boley SJ. 1991. Annu Rev Med. 42:107
5. Kumar S, Sarr MG, Kamath PS. 2001. NEJM. 345(23):1683
6. Haberer J, Trivedi NN, Kohlwes J, Tierney L Jr. 2003. NEJM. 349(1):73 (Case Discussion)