DVT After Knee and Hip Surgery: To Test or Not to Test?
The prevalence of deep vein thrombosis (DVT) after hip- or knee-joint replacement is high, according to a study reported in the latest issue of the Medical Journal of Australia. While many DVTs are relatively harmless, some are associated with pulmonary embolism, which, in rare instances, can be fatal.
Researchers Richard O'Reilly, Ian Burgess and Bernard Zicat studied about 6000 patients undergoing total hip replacement or total knee replacement surgery at the Mater Misericordiae Hospital, North Sydney, between 1995 and 2001.
Despite short-term prevention measures, including the use of anticoagulants and surgical stockings, ultrasound imaging before discharge showed a DVT prevalence of 8.9 per cent after total hip replacement, 25.6 per cent after total knee replacement, and 36.9 per cent after bilateral total knee replacement. The prevalence of symptomatic non-fatal in-hospital pulmonary embolism was 1.9 per cent, while the prevalence of fatal in-hospital pulmonary embolism was 0.05 per cent.
All patients underwent ultrasonography of both legs before discharge. Although pre-discharge ultrasound screening of all patients after hip or knee replacement involves significant time and expense, the authors believe that screening is helpful, given the uncertain behaviour of postoperative deep vein thrombi. Screening assists in planning post-discharge management, an important consideration for the many patients who face long trips home by car or by plane, often to small centres with limited medical facilities.
"Extended anticoagulation for four to six weeks after leaving hospital has the problem that it has to be self-administered by the patient and may cause unwanted bleeding," Dr O'Reilly said.
"Only one in six of our 6,000 patients developed a clot before leaving hospital. A policy of extended treatment with anticoagulation for four to six weeks after discharge means many patients would be unnecessarily treated," Dr O'Reilly said.
In an editorial in the same issue of the Journal, Alexander Gallus, Director of Pathology Services at SouthPath, Flinders Medical Centre, cautions that there is still no definitive evidence that ultrasound screening at discharge brings clinical benefit.
Moreover, he estimates that performing ultrasonography on all patients after hip or knee replacement would cost about $200 000 per 1000 patients.
He suggests that extended DVT prevention measures (continuing for 4-6 weeks after surgery) are likely to be the simplest, cheapest and perhaps safest solution.
The Medical Journal of Australia is a publication of the Australian Medical Association.
CONTACT Dr Richard O'REILLY, 0408 226 089 / 02 9953 1104
Professor Alexander GALLUS, 0410 729 965 / 08 8204 5209
Judith TOKLEY, AMA Public Affairs, 0408 824 306 / 02 6270 5471