A positive diagnosis of a DVT can only be made if the venogram is positive or there is a positive venous ultrasound at two or more sites of the proximal veins. A negative diagnosis for DVT can be made if there is a negative venogram, a negative d-dimer test or a normal venous ultrasound assuming the venous ultrasound is accompanied by one of the following findings: 1) low clinical suspicion for DVT, or 2) normal d-dimer test, or 3) normal serial testing with the test interval being no greater than 1 week.
Furlan and Fehlings (2007) in their review noted that, “there is insufficient evidence to support (or refute) a recommendation for routine screening for DVT in adults with acute traumatic SCI under thromboprophylaxis.” The same authors note that, “The screening test of choice for asymptomatic DVT needs to be determined. A systematic review on noninvasive diagnosis of DVT from the McMaster Diagnosis of Deep Venous Thrombosis Working Group indicated that: 1) venography is the only reliable test for the diagnosis of asymptomatic DVT; 2) the role of surveillance testing with ultrasound in asymptomatic patients at high risk of DVT is uncertain; and 3) surveillance testing with impedance plethysmography is not recommended (Kearon et al. 1998).”