Blood Clots (cont.)
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How are blood clots diagnosed?
The first step in making the diagnosis of a blood clot is obtaining a history from the patient for family. Patients rarely are able to make their own diagnosis of a blood clot so the health-care professional will need to ask questions about what might be happening. If a blood clot or thrombus is a consideration, the history may expand to access the patient's risk factors or situations that might have put the patient at risk for forming a clot.
Physical examination will help add information to increase the suspicion for a blood clot.
Testing for venous blood clots
Testing will depend on the suspected location of the blood clot.
Computerized tomography (CT) is often the test of choice when suspicion of pulmonary embolus is high. Contrast is injected intravenously, and the radiologist can determine whether a clot is present.
On occasion, ventilation perfusion (V/Q) scans are performed to look for pulmonary emboli. This test uses labeled chemicals to identify inhaled air into the lungs and match it with blood flow in the arteries. This test is less accurate than a CT scan and is subjective to variances in interpretation.
Should a pulmonary embolus be diagnosed, the amount of clot and potential severity of the disease may require further testing. Echocardiogram is an ultrasound of the heart that may be used to decide how much strain the blood clot in the lung is causing on the heart.
Testing for arterial blood clots
Arterial thrombosis is an emergency, since tissue cannot survive very long without blood supply before there is irreversible damage. In an arm or leg, often a surgeon is immediately consulted. Arteriography may be considered. Arteriography is a technique in which dye is injected into the artery in question to look for blockage. Sometimes, if there is a large artery that is occluded, this test is done in the operating room with the presumption that a surgical procedure will be necessary to open the vessel and restore blood flow.
For an acute heart attack, the EKG may confirm the diagnosis, although blood tests also may be used to look for enzymes (troponin) that leak into the bloodstream from irritated heart muscle. With an acute heart attack, the diagnostic and therapeutic procedure of choice is a heart catheterization. A catheter is placed into the coronary artery, the blockage identified and a stent placed to restore blood supply to heart muscle.
Other variations of head CT may be considered to look at blood flow in the brain (perfusion CT) or the arteries themselves (CT angiogram).
For an acute stroke (cerebrovascular accident, CVA), the test of choice is a computerized tomography (CT) scan of the head to look for bleeding or tumor as the cause of stroke symptoms. If the stroke symptoms resolve, meaning that a transient ischemic attack (TIA) has occurred, tests may include carotid ultrasound to look for blockage in the major arteries of the neck and echocardiography to look for blood clots in the heart that may embolize to the brain.
Medically Reviewed by a Doctor on 5/13/2016
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