Diagnosis of Suspected Recurrent Deep Venous Thrombosis Using d-Dimer and Compression Ultrasonography FREE

Deep venous thrombosis (DVT) occurs when blood clots form in the large veins of the legs. Patients with DVT require treatment with blood thinners (anticoagulants) to help dissolve the clots. Before starting treatment with anticoagulants, doctors must be certain that the diagnosis of DVT is correct because these drugs, although appropriate for treatment of DVT, can also cause serious bleeding. Researchers have proven that several tests are reliable for diagnosing DVT when the condition occurs for the first time. However, after the condition has occurred once, the tests can be much less reliable for diagnosing a recurrence. Some of the changes caused by the first episode do not resolve promptly and may falsely indicate that a new clot has formed. As many as two thirds of patients with a suspected recurrence of DVT actually do not have new clots. To avoid treating patients unnecessarily, doctors often perform many confirmatory tests. Recently, researchers have observed that a test known as d dimer will produce positive results in patients with active clots but not in patients who do not have DVT.

To determine whether it was safe to withhold anticoagulant therapy from patients who were suspected of having recurrent DVT but who had a negative d dimer result.

300 patients with a confirmed history of DVT and symptoms suggestive of recurrent DVT.

All patients in the study had d dimer testing. If the d-dimer result was negative, no additional tests were performed and no anticoagulation with heparin was given, regardless of the patient's symptoms. If the d-dimer result was positive, additional tests were performed and patients were treated appropriately. Patients were reevaluated if they later developed symptoms suggestive of another episode of DVT. After 3 months, the researchers reevaluated the patients to see whether they had had DVT during that time.

134 patients had negative d-dimer results and were not treated. During the 3-month follow-up period, 11 patients with negative d-dimer results had symptoms suggestive of recurrent DVT and came back for additional testing. One of the 11 patients had a confirmed blood clot and died. Of the remaining 10 patients, additional testing ruled out recurrent blood clots in 4. Additional testing was inconclusive in another 5. One patient with recurrent symptoms did not have additional testing.

Because of the uncertainty of diagnosis in several cases, this study does not provide an exact estimate of the incidence of recurrent blood clots in the follow-up group.

It seems to be safe to withhold anticoagulant medication in a large proportion of patients with suspected recurrent DVT if the d-dimer result is negative.