Blood clots may not originate in veins

BOSTON, Oct. 21 (UPI) -- The teaching that pulmonary embolisms -- blood clots in the lungs -- originate in deep veins may not be correct, U.S. researchers say.

The study, published in the Archives of Surgery, studied demographic information as well as imaging scans taken from 2004 to 2006 of the lungs and veins of 247 trauma patients.

Dr. George C. Velmahos and colleagues at Massachusetts General Hospital and Harvard Medical School in Boston found 46 patients were diagnosed with pulmonary embolism and 18 had deep venous thrombosis. Seven patients with pulmonary embolism also had deep venous thrombosis. There were no differences between patients with pulmonary embolism who did and did not have deep venous thrombosis in any of the demographic or clinical variables assessed, the researchers said.

The researchers propose many pulmonary embolisms may form primarily in the lungs.

"Based on these data, there is little evidence that pulmonary embolism originates from deep venous thrombosis of peripheral veins," the study authors said in a statement.

"As computed tomographic venography -- vein imaging -- becomes more popular and accurate, this issue will be further explored, and it may be revealed that -- not surprisingly -- we have been preaching and practicing the wrong dogma for years."