D-dimer as a screening test for suspected DVT

Last reviewed 01/2018

• Lennox et al (1) undertook a study of 200 consecutive inpatients and outpatients with suspected DVT. Of the 200 patients, 14% of patients had a proximal (thigh veins) DVT and 9% had an isolated calf DVT - this study revealed a sensitivity of the D-dimer assay of 100% in the detection of a proximal DVT and 91% for all DVTs
• the sensitivity for the detection of proximal DVTs via the use of D-dimer assay was only 89% in a study of 360 consecutive patients with a suspected DVT in a study by Aschwanden et al (2). This may reflect that this study included patients with a history of a previous DVT and may have a higher proportion of patients with less extensive DVTs
• a more recent study in outpatients with suspected DVT, revealed that the use of D-dimer testing reduced the need for venous ultrasonographic imaging and ruled out DVT in patients judged clinically unlikely to have a DVT (3). The table below is of D-dimer testing plus venous ultrasonographic imaging versus venous ultrasonographic imaging alone in suspected DVT at 3 months (3)

  outcome	D-dimer + venous ultrasonographic imaging	venous ultrasonographic imaging alone	difference between the groups (95% CI)
  development of DVT or PE in patients in whom DVT had been initially ruled out	0.42%	1.35%	-0.93 (2.2 to 0.2) not significant

Notes:

• for diagnosis of DVT, the ELISA and quantitative rapid ELISA are more sensitive than latex and whole blood agglutination assays (4)
• a normal result on the highly sensitive D-dimer test (ELISA) is effective for ruling out DVT in patients with a low to moderate clinical probability of DVT (5)
• there are various situations where there may be a false negative D-dimer (6) - this study analysed false negative results occurring with the Simpli-Red agglutination assay
  • (LMW)heparin treatment, symptoms of venous thromboembolism for more than 10 days or less than 24 hours and a very small thrombus load, are associated with an increased risk for a false-normal D-dimer test result, although the clinical usefulness of these criteria to adequately identify those patients with a false-normal D-dimer outcome appears to be limited (6)

Reference:

1. Aschwanden M, Labs KH, Jeanneret C et al . The value of rapid D-dimer testing for combined with structural clinical evaluation for the diagnosis of deep vein thrombosis. J Vasc Surg 1999;30: 929-35.
2. Lennox AF, Delis KT, Serunkuma S et al. Combination of a clinical risk assessment score and rapid whole blood D-dimer testing in the diagnosis of deep vein thrombosis in symptomatic patients. J Vasc Surg 1999;30: 794-804.
3. Wells PS et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med 2003;349:1227-35.
4. Stein PD et al. D dimer for the exclusion of acute venous thrombosis and pulmonary embolism: a systematic review. Ann Intern Med 2004;140:589-602
5. Fancher TL et al. Combined use of rapid D-dimer testing and estimation of clincal probability in the diagnosis of deep vein thrombosis: systematic review. BMJ 2004;329:821.
6. Kraaijenhagen RA et al.Can causes of false-normal D-dimer test be identified.Thrombosis Research 2003 ;111(3):155-158.