DIAGNOSIS OF DEEP VENOUS THROMBOSIS: NON-INVASIVE VS INVASIVE DIAGNOSTIC PROCEDURES

The clinical diagnosis of deep vein thrombosis (DVT) in symptomatic patients is unreliable. The need for objective diagnostic tests is widely acknowledged. Contrast venography in experienced hands is considered to be the reference method. This method is invasive, uncomfortable to the patient, not easily repeatable and expensive.

For this reason several non-invasive tests have been developed and evaluated recently. Of the non-invasive tests impedance plethysmography (IPG) has been thoroughly evaluated in properly designed prospective clinical trials. Serial IPG in symptomatic outpatients is safe and effective. It was shown in longterm follow-up that anticoagulant treatment could be safely withheld in over 500 patients with repeatedly normal IPG (0.3-0.6% recurrence DVT). The specificity for proximal DVT was 92%. The feasability of IPG in symptomatic outpatients was over 95%. The safety of withholding anticoagulant treatment in symptomatic inpatients with a serial normal IPG is an unresolved issue. Preliminary results show that a similar sensitivity might be obtained in inpatients, however, the feasability was lower (87%).

Doppler ultrasound has been studied extensively, however, there is a great variation in reported sensitivity for proximal DVT due to the lack of objective diagnostic criteria and the safety of withholding anticoagulant treatment in patients with serial normal Doppler tests results is not es tablished.

strain gauge plethysmography has not been evaluated properly and therefore awaits further studies. ¹²⁵I-fibrinogen legscanning has been shown to be sensitive for calf vein thrombosis (over 90%). In combination with IPG this method is a safe and effective alternative to venography.

Radionuclide phlebography has never been evaluated in prospective clinical trials in a broad spectrum of symptomatic patients, and can therefore not be recommended for routine use.

It is concluded that presently the management of patients with clinically suspected DVT should be performed with the use of serial IPG, IPG in combination with ¹²⁵I—fibrinogen legscanning or contrast venog raphy.