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Blood Clots

How are blood clots found or diagnosed?

The first step in making the diagnosis of a blood clot is talking to the patient and family to understand the situation. The blood clot itself does not cause a problem. It's the location of the blood clot and its effect on blood flow that causes symptoms and signs. If a blood clot or thrombus is a consideration, the history may expand to explore risk factors or situations that might put the patient at risk for forming a clot.

Venous blood clots often develop slowly with a gradual onset of swelling, pain, and discoloration. Symptoms of a venous thrombus will often progress over hours.

Arterial thrombi occur as an acute event. Tissues need oxygen immediately, and the loss of blood supply creates a situation in which symptoms begin immediately.

There may be symptoms that precede the acute artery blockage that may be warning signs of the potential future complete occlusion of the blood vessel.

  • Patients with an acute heart attack may experience angina or chest discomfort (pressure, pain, indigestion, fatigue) in the days and weeks prior to the heart attack. It is important to remember that women may experience atypical and non-specific symptoms as part of their angina equivalent, including fatigue and malaise.
  • Patients with peripheral artery disease may have pain with walking (claudication)
  • A TIA (transient ischemia attack, mini-stroke) in which the symptoms resolve without treatment may precede a stroke.

Physical examination can assist in providing additional information that may increase the suspicion for a blood clot.

  • Vital signs may be helpful in deciding how stable the patient is doing. These include blood pressure, pulse rate, respiratory rate, body temperature and oxygen saturation (what percentage of red blood cells have oxygen attached).
  • Heart monitoring and an EKG may be ordered to assess heart rate and rhythm.
  • Venous thrombi may cause swelling of an extremity (arms, legs). The limb may appear to be red, warm, and tender; sometimes the appearance is difficult to distinguish from cellulitis or an infection of the extremity. If there is concern about a pulmonary embolus, the doctor may examine the lungs to listen for abnormal sounds caused by an area of inflamed lung tissue.
  • Arterial thrombus symptoms are much more dramatic. If a leg or arm is involved, the tissue may be white because of the lack of blood supply. Also, it may be cool to touch and there may be loss of sensation and movement (paralysis). The patient may be writhing in pain.

Arterial thrombus is also the cause of heart attack and stroke (cerebrovascular accident) and their associated symptoms.

Reviewed on 10/28/2016
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