Deep vein thrombosis: I-125 fibrinogen leg scanning was not useful for diagnosing DVT.

Clinical bottom line (level 4)

  1. In patients with suspected deep vein thrombosis or pulmonary embolism, I 125 fibrinogen leg scanning was unhelpful in diagnosing DVT.
Browse et al: British Medical Journal 1971; 4: 325-328
Expires December 2003

The study

Setting: teaching hospital, UK

102 patients (aged range 19 to 79 years; mean 52, 50% male) suspected deep vein thrombosis or pulmonary embolism (156 legs in 102 patients)

Independent unblinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • contrast venogram
Diagnostic test: I-125 fibrinogen scanning: patients received 90 mg of potassium iodide. 1 mg of fibrinogen injected and leg examined for increased radioactivity compared with theother leg 18-24 hours later. Positive if 3 x 5%.

The evidence

pre-test probability of deep vein thrombosis: 95%, (95% CI: 22% to 37%)

diagnostic test DVT no DVT LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
positive leg scan 20 16 2.99
(1.71 to 5.23) 		56% 0.66
(0.51 to 0.86) 		22%
total 46 110

Comments

  1. Fibrinogen scan: radioactive fibrinogen incorporated into thrombus when forming.
  2. Study looked at patients with wide duration of symptoms and 64% on anticoagulant- ?some clots dissolving.
  3. Historical test; I-125 no longer commercially available

Citation

  1. Browse NL, Clapham WF, Croft DN, et al: Diagnosis of established deep vein thrombosis with I 125 fibrinogen uptake test. British Medical Journal 1971; 4: 325-328
Contributor: Chris Ball and Clare Wotton, May 2000
Reviewer: Alex Gallus

Clinical Question.
Patient suspected DVT or PE
Intervention or Exposure I-125 scan
Comparison contrast venogram
Outcome diagnosis