Clinical Diagnosis of Arterial TOS

Arterial TOS is rare, but may cause severe complications. The presentation of arterial TOS is dramatic and usually quite obvious. Doctors make the clinical diagnosis of arterial TOS promptly and accurately in most cases. Primary treatment of the arterial blood clot should begin almost immediately.

Blood clot causes arm swelling

Physical Examination of Arterial TOS

Arterial TOS presents in a dramatic fashion, with potentially severe complications. Thus, a doctor would promptly begin with a physical examination focused on finding one or more of 4 pathologic processes.

  • Acute arterial insufficiency- a blood clot causes critical loss of blood flow in a large artery

  • Emboli-blood clot fragments that break off and travel to smaller arteries

  • Aneurysm-focal dilation and ballooning of a damaged artery

  • Chronic arterial insufficiency-chronically limited arterial blood flow caused by stenosis or chronic clot

Acute arterial occlusion puts the patient at risk of permanent tissue loss and loss of function. Because of this risk, a physician will always look for signs of acute arterial insufficiency, including the 5 Ps:

  • Pain

  • Pallor-pale or white color

  • Paresthesias-tingling

  • Pulselesness-loss of expected arterial pulse

  • Paralysis-loss of strength or function

After this, the physician will look for signs of arterial emboli. These signs include skin ulcerations and discoloration, and splinter hemorrhages. Splinter hemorrhages are tiny blood clot fragments (emboli) that travel from the damaged artery to small arteries in the fingers. These emboli cause tiny hemorrhages where they lodge, which appear as tiny black spots. Thus, splinter hemorrhages are a sign of a proximal blood clot, usually in the arteries or heart.  The presence of splinter hemorrhages necessitates a search for the source of emboli.

Your doctor will also examine the thoracic outlet on each side for the presence of a pulsatile mass. This mass may prove a subclavian artery aneurysm, or a normal subclavian artery passing over a cervical rib. With or without an aneurysm, your doctor may hear a bruit in the thoracic outlet with her stethoscope. A bruit is a swooshing sound caused by turbulent arterial blood flow. Narrowing of an artery may cause blood pressure in the two arms to be different. Finally, your physician will look for signs of chronic arterial insufficiency, including chronic skin changes.

Imaging Tests

Imaging tests are incredibly valuable tools in modern medicine. They are particularly valuable for a disease in a complex anatomic area like the thoracic outlet. In patients with arterial TOS, imaging tests confirm the doctor’s clinical diagnosis in several important ways. Read more about the value of imaging tests here.


Critical treatment decisions revolve around the presence or absence of a blood clot causing arterial occlusion. When present, acute arterial occlusion demands urgent treatment. When absent, surgeons can assess and treat patients with arterial TOS less urgently.

Read more about the treatment of patients with arterial TOS here.

This interactive media demonstrates MR angiography images in two patients. Swipe between the two to demonstrate a normal MR angiogram and an MR angiogram with bilateral extrinsic compression.

Imaging Diagnosis of Arterial TOS

Your doctor can see evidence of arterial narrowing or occlusion. Imaging tests will show arterial damage, such as stenosis or aneurysm. The same imaging tests can show the presence of blood clot, either locally or distant to the damaged artery. Imaging tests will show how much blood flow is present, or if the artery is completely occluded. Some imaging tests, such as MRI, show the structures that caused arterial damage to begin with. These tests help doctors make critical decisions in treating patients with arterial TOS. Learn more about the clinical diagnosis and imaging of arterial TOS here.

Treatment of Arterial TOS

Doctors urgently treat arterial occlusion by dissolving or removing the blood clot causing occlusion. After doctors restore arterial blood flow, the must treat the damaged arterial segment, and remove any structures compression this segment. Learn more about the treatment of arterial TOS here.