Diagnosing DVT (Deep Vein Thrombosis)
The most commonly used test to check for DVT is duplex ultrasonography, which has very good sensitivity and specificity in certain patients. It is most reliable when used on patients who are symptomatic, especially when the symptoms are localized above the knee and below the groin.
The most accurate test for DVT is venography, in which dye is injected into the veins of the involved leg. venography is rarely performed today unless it is used for therapeutic purposes, such as with catheters to remove deep vein clots to confirm their presence and remove them with suction catheters.
A blood test can also be done, which checks for D-dimer fragments. This test is of limited usefulness, however, as it has a high rate of false positives.