Diagnosis of deep-vein thrombosis using objective doppler method
Deep-vein thrombosis is a condition characterized by the development of blood clots (thrombi) in the deep veins. When a thrombus breaks off and travels within the circulatory system, it is called an embolism. Almost 300,000 new cases of lung (pulmonary) embolisms and deep-vein thrombosis are diagnosed each year in the United States. Thrombi are treated with anticoagulants that dissolve blood clots. In the past, deep-vein thrombosis was diagnosed with contrast venography, a procedure where dye is injected into a vein, and pictures are taken using a certain type of radiation. Although this method was effective, it was also invasive and uncomfortable for the patient. Plethysmography can also be used to diagnose such conditions, and is a procedure where the size of an organ or extremity is measured based upon variations in the amount of blood passing through or contained in that part. This diagnostic method for the evaluation of symptomatic patients is currently the standard against which other, newer diagnostic therapies are measured. The doppler method for diagnosing deep-vein thrombosis involves the use of sound to detect the presence of thrombi, but well defined, standardized criteria for the execution and interpretation of the test have been lacking. A recent study examined the diagnostic criteria and assessed the effectiveness of the doppler method as compared with the contrast venography method. Contrast venography showed that 45 out of 155 patients had thrombosis. Of these 45 patients, 41 also had abnormal doppler tests. When the reproducibility of the doppler method was examined, independent examiners agreed on the diagnosis more than 95 percent of the time. The doppler method was more accurate when the popliteal vein of the leg was used than when both the popliteal and femoral veins of the leg were used. The data indicate that the doppler method has an accuracy rate of between 91 and 99 percent. This method has the advantages that it can be used in almost all patients, has no side effects, is cheap, and can be used repeatedly to monitor patients. The only drawback is its inability to detect thrombi in the calf vein. The doppler method is an accurate diagnostic tool for patients suspected of having deep-vein thrombosis, but the safety of withholding anticoagulant therapy based on normal findings with this test is questionable and awaits further study. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Annals of Internal Medicine
Detection of deep-vein thrombosis by real-time B-mode ultrasonography
It has been shown that diagnosing a deep vein thrombosis, the interruption of circulation caused by the presence of a blood clot, based on clinical symptoms and signs in outpatients is unreliable. In addition, there are problems of painfulness and difficulty in interpreting results with the standard, invasive method of detecting clots in the deep veins by contrast venography (X-rays of veins after injection of contrast medium into bone marrow). The diagnostic effectiveness of noninvasive B-mode ultrasonography, which uses ultrasound to detect and produce images of the thrombi, or clots has broad clinical application. This method was compared to contrast venography in 220 patients suspected of having deep-vein thrombosis of the leg. B-mode ultrasonography measured the degree to which the suspected thrombotic vein could be compressed by means of a probe; full compression indicating no thrombus and no compression indicating presence of thrombus. In 142 of the 143 patients who had normal venograms, veins proved fully compressible. In 66 patients diagnosed with thrombosis by venogram, all had femoral or popliteal veins that were not compressible. However, B-mode ultrasonography was only able to detect 36 percent of calf vein thrombosis previously diagnosed by venogram. When the compression ultrasound test was repeated on 45 patients, results were in agreement with the first ultrasound test. The authors conclude that B-mode ultrasonography using vein compressibility as the only criterion is an accurate, simple, and painless method of detecting femoral and popliteal deep-vein thrombosis.
Publication Name: The New England Journal of Medicine
Deep-vein thrombosis and the incidence of subsequence symptomatic cancer
There may be an association between deep-vein thrombosis and the development of cancer, especially in patients who have recurrent episodes of unknown cause. Deep-vein thrombosis is the formation of a blood clot in a major vein. Among 250 patients with a first episode of deep-vein thrombosis who were followed over a two-year period, 145 were diagnosed with idiopathic venous thrombosis, or thrombosis of unknown cause, and 105 developed a venous thrombosis secondary to another disease. Eleven patients (7.6%) with idiopathic venous thrombosis developed symptomatic cancer during the follow-up period, compared with two patients (1.9%) with secondary venous thrombosis. Thirty-five patients with idiopathic venous thrombosis had recurring episodes of thrombosis. Six of these patients (17%) later developed cancer. Some patients with recurrent idiopathic venous thrombosis may be suffering from cancer, but have not developed symptoms yet.
Publication Name: The New England Journal of Medicine
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