In most patients with venous TOS, laboratory tests do not contribute significant diagnostic information. However, in a few selected patients, laboratory diagnosis of venous TOS may demonstrate ‘thick’ blood that clots easily. For the most part, doctors can make the presumptive diagnosis of venous TOS promptly, based on their clinical examination. Specifically, your doctor can find secondary signs of a blood clot, even if they do not directly see the clot. Subsequently, your doctor will almost always order imaging tests to confirm the blood clot. Doctors consider the prompt treatment of this clot as the first step in the definitive treatment of venous TOS.
Laboratory diagnosis of venous TOS
In most patients, the laboratory diagnosis of venous TOS is normal. In a few patients, the laboratory diagnosis of TOS is abnormal. The most frequent abnormal finding is hypercoagulable blood, or blood that clots too easily. Thus, in most patients, evaluation of blood clotting is not helpful in confirming the diagnosis or altering treatment decisions.
At the present time, we still do not understand why some patients develop venous blood clots, and others do not. For one thing, imaging studies prove that many normal people develop compression of the subclavian veins when raising their arms. On the other hand, the vast majority of these people do not develop blood clots in these veins. So what is the difference between those with vein compression and those who develop blood clots?
While the laboratory diagnosis of venous TOS adds little information, doctors can easily confirm the diagnosis through other methods. Patients usually have dramatic symptoms. Doctors find obvious signs of venous obstruction on clinical examination. Imaging tests are definitive. Thus, the diagnosis of venous TOS does not depend on the laboratory test results.