First Things First (assess & treat for the following)

Make the diagnosis: The key to mgt is early diagnosis & treatment before irreversible ischemia occurs. The problem is that the early signs & symptoms of a devastating problem are often subtle, & routine tests are not sensitive or specific.

• Diagnosis should be suspected on clinical grounds based on a high degree of suspicion. The differential diagnosis includes:
  • The most common causes of acute bowel ischemia are related to obstruction. About 33% of complete small bowel obstructions are complicated by strangulation due to mid-gut volvulus, adhesions or a incarcerated hernia. Consider:
    • Previous abdominal surgery
    • Hernia
    • History of congenital defects
  • The second most common cause of acute mesenteric ischemia is primary vascular occlusion due to hemorrhage into an existing mesenteric arterial atherosclerotic plaque w/ subsequent narrowing & thrombosis or to embolization of clot from a proximal site. Consider:
    • Atherosclerotic peripheral vascular disease
    • History of intestinal angina w/ dehydration
    • Atrial fibrillation
    • CHF
    • Recent cardiac catheterization, cardioversion or arteriogram
  • Traumatic disruption of 2 or more mesenteric vessels occasionally causes acute ischemia. A few pts experience slow progressive stenosis of 2 or more mesenteric arteries related to atherosclerosis or vasculitis. Consider:
    • Abdominal trauma
    • Recent abdominal surgery including aortic aneurysm repair, bowel resection, colostomy
  • Rarely, primary vascular occlusion is related to venous thrombosis precipitated by a hypercoagulable state, dehydration, portal hypertension & polycythemia. Consider:
    • History of thrombophlebitis
    • Recent portal vein surgery
    • Pregnancy
  • Finally, nonocclusive mesenteric ischemia is related to low-flow states of CHF, cardiac arrhythmias & aortic valve insufficiency, usually underlying profound splanchnic vasospasm in response to:
    • Shock
    • Sepsis
    • Respiratory insufficiency
    • Recent cardiopulmonary bypass
    • Recent hemodialysis
    • Administration of vasoconstrictors such as
      • Epinephrine
      • Digitalis
    • Cocaine abuse

• Diagnosis is confirmed by angiography or laparotomy.