Definition

Mesenteric ischemia is a reduction in intestinal blood flow. There are four causes of mesenteric ischemia: arterial emboli, arterial thrombosis, venous thrombosis and non-occlusive ischemia. Mesenteric ischemia may lead to sepsis, bowel infarction, and death. If diagnosis takes place before infarction occurs, mortality is low. Diagnosis made after infarction results in mortality ranging between 70%-90%. Vague nonspecific symptoms make this a challenge to diagnose.

Intestinal ischemia can be divided into acute and chronic, based upon the rate of onset and the degree to which blood flow is compromised. Acute mesenteric ischemia refers to the sudden onset of intestinal hypoperfusion, which can be due to occlusive or nonocclusive obstruction of arterial or venous blood flow. Chronic mesenteric ischemia (also called intestinal angina) refers to episodic or constant intestinal hypoperfusion, which usually develops in patients with mesenteric atherosclerotic disease.

Key History

Physical Exam

Risk Factors for Mesenteric Ischemia

Differential Diagnosis

Diagnostic Testing

The recommended diagnostic tests for mesenteric ischemia, both acute and chronic, are primarily imaging-based, with a focus on identifying vascular occlusions and bowel ischemia.

• Computed Tomography Angiography (CTA): The Society for Vascular Surgery recommends CTA as the preferred definitive imaging test for mesenteric artery occlusive disease (MAOD) due to its high sensitivity and specificity. CTA is particularly useful for visualizing the mesenteric vessels and assessing the extent of ischemia.


• Duplex Ultrasound (DUS): DUS is an excellent screening tool for MAOD. It is non-invasive and can provide information on blood flow and vessel patency.


• Magnetic Resonance Angiography (MRA): MRA can be considered as an alternative to CTA, especially in patients with contraindications to iodinated contrast. However, it is less effective in evaluating ischemic bowel changes compared to CTA.


• Conventional Arteriography: This is reserved for cases where CTA or MRA are inconclusive or when endovascular intervention is planned. It provides detailed images of the mesenteric vasculature and can differentiate between occlusive and non-occlusive ischemia.


• Laboratory Tests: While not diagnostic, elevated levels of D-dimer and lactate can support the diagnosis of acute mesenteric ischemia. However, these tests lack specificity and should not be solely relied upon.

Clinical Risk and Safety Pearls

• Immediate treatment of hemodynamic status (hypotension, CHF).
• Any abdominal pain patient with a metabolic acidosis should be considered for mesenteric ischemia until proven otherwise.
• Normal labs do not exclude the diagnosis of mesenteric ischemia.
• A rectal exam may be of use in these patients with abdominal pain. A positive guaiac with no other apparent cause of GI bleeding may increase clinical suspicion for mesenteric ischemia.
• Patients with mesenteric ischemia and signs of peritonitis generally require immediate surgical intervention.
• This diagnosis is often delayed. Risk of delay can be reduced by maintaining a high clinical suspicion and use of early diagnostic imaging and early surgical consultation.

Treatment

Initial Management:

• Resuscitation: Immediate fluid resuscitation and correction of metabolic acidosis are critical. Broad-spectrum antibiotics should be administered to prevent sepsis from bacterial translocation.


• Anticoagulation: Systemic anticoagulation with heparin is initiated to prevent further thrombus formation.

• Endovascular Therapy: For arterial embolism or thrombosis, endovascular techniques such as aspiration embolectomy, thrombolysis, and angioplasty with or without stenting are preferred due to lower morbidity and mortality compared to open surgery.


• Surgical Intervention: Open surgical approaches—including embolectomy, bypass grafting, and resection of nonviable bowel—are indicated when endovascular options are not feasible or if there is evidence of bowel infarction. The American College of Cardiology and the American Heart Association recommend surgical revascularization in cases where endovascular therapy is not sufficient.


• Second-Look Surgery: A planned second-look laparotomy within 24-48 hours is often necessary to reassess bowel viability and prevent further complications.

• Mesenteric Venous Thrombosis: Systemic anticoagulation is the mainstay of treatment, with endovascular intervention reserved for cases not responding to anticoagulation.