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Post-Op Blood Clot Risk High

Study Finds Postoperative Blood Clot Risk Greater, More Persistent Than Experts Thought

Blood Clot Risk After Surgery: Study Results continued...

The numbers vary by surgery, Green found. ''The riskiest are the major operations -- hip replacement, knee replacement, and other major orthopedic operations, such as operations for hip fractures," Green tells WebMD. Her findings:

•         1 in 45 had clots after hip or knee replacement

•         1 in 85 after cancer surgery

•         1 in 815 after day surgery

•         1 in 6,200 women who did not have surgery

Lack of movement is mostly to blame, Green says. "Your legs are immobile, and you don’t have the normal mechanism where muscles are helping blood flow. Some anesthetics increase the risk even further by causing veins in the leg to dilate, so there is more pooling of blood."

Cancer itself may also trigger blood changes that boost blood clot risk, she says.

The study results, Green says, may inspire doctors and policy makers to extend the typical time that preventive measures such as anticoagulants and compression stockings are used. Those times vary, with some ending at hospital discharge and others continuing for up to four weeks, she writes.

Blood Clot Risk Post-Op: Other Opinions

The study is an important one, says James Muntz, MD, clinical professor of medicine at Baylor College of Medicine in Houston. Muntz, an internist, recently published a paper advocating extended-duration therapy to prevent clots after orthopedic surgery. He says he isn't sure the new findings will inspire an immediate change in guidelines for preventing clots. "I think it will at least trigger a change in people's awareness,'' he says. And prolonged preventive measures would be expected to be as good for men as for women, he says.

Another physician in practice, Charles F. Chandler, agrees. ''The study is important because it raises an index of suspicion that this phenomenon can occur after relatively minor procedures and for a long period of time."

Chandler is a general surgeon at Santa Monica-UCLA Medical Center and Orthopaedic Hospital and a clinical professor of surgery at the University of California Los Angeles David Geffen School of Medicine. One limitation of the study, also pointed out by the authors, is that no information was available on whether the women took preventive measures to avoid clots, he says.

Blood Clot Risks: What Can Patients Do?

Surgeons routinely caution their patients to be aware of potential symptoms of blood clots, Green says. Her advice to surgery patients in the wake of her new findings? "To repeat what they will have been told by their surgeon -- the message than an unexplained pain in the calf, or swelling, can be a sign, and not to dismiss it, even if it's several months after the surgery.''

Chandler tells his surgery patients: "Treat it like an injury" and give the body time to heal. ''We want patients to be proactive," he says. "Ask your surgeon: 'What is my risk of a blood clot?'"


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