First, perform compression ultrasonography. If positive, then treat for deep vein thrombosis.
If compression ultrasonography is negative, then one or more of the following are done.
(1) Consider clinical probability for deep vein thrombosis
(1a) If the risk is low, then deep vein thrombosis is excluded.
(1b) If the risk is moderate or high, then perform a repeat ultrasonography (below).
(2) Perform a D-dimer test
(2a) If the D-dimer test is positive, then perform a repeat ultrasonography (below)
(2b) If the D-dimer test is negative, then deep vein thrombosis is excluded.
(3) Repeat ultrasonography, typically after 1 week, if there is continued clinical suspicion for deep vein thrombosis
(3a) If the repeat ultrasonography is positive, then treat for deep vein thrombosis.
(3b) If the repeat ultrasonography is negative, then deep vein thrombosis is excluded.
