Dangerous blood clots don't require big injuries

January 15, 2008 2:53:18 PM PST
A new study shows that even fairly common leg injuries could lead to serious complications

Muscle ruptures, ankle sprains and other common minor leg injuries can arry a higher risk for blood clots in the legs or lungs, according to a report in the January 14 issue of Archives of Internal Medicine.

Doctors have long known that major injuries increase the risk for venous thrombosis. Those clots are especially dangerous when they travel to the lungs. But in addition to the injuries, there are other risk factors, such as surgery, a plaster cast, hospitalization, and extended bed rest that come along with major injuries.

What doctors wanted to know was whether the injury itself, or the surrounding factors were the big threat,

After studying 25-hundred people who developed venous thrombosis between 1999 and 2004, researchers at Leiden University Medical Center, Leiden, the Netherlands, found that even minor injuries tripled the relative risk of blood clots.

"The association appeared local because injuries in the leg were associated strongly with thrombosis, while injuries in other locations were not associated with thrombosis. The association was strongest for injuries that occurred in the month before the venous thrombosis, suggesting a transient effect." The association was also stronger in individuals with genetic or other risk factors for blood clots.

There are several reasons such injuries may increase the risk of blood clots, the authors note. Even injuries that do not require an individual to be completely immobilized may cause them to be less active, potentially leading to blood clots. In addition, damage to the blood vessel wall from an injury also could increase clotting risk in the affected area.

"Because minor injuries are common, they can be major contributors to the occurrence of venous thrombosis," the authors conclude. "Many individuals with minor injuries will have contacted the general practitioner first. Therefore, there may be an important task for general practitioners to identify subjects who are at high risk of developing venous thrombosis and subsequently to provide prophylactic measures."