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Letter to the editor
Editor, – I read with interest Drs Tay and McGrath's article 'Diagnosis of deep vein thrombosis' (Aust Prescr 1998;21:76-9) and the challenge it frequently presents. I note that, in the management of isolated calf vein thrombosis without ongoing risk factors, they advocate withholding anticoagulation and repeat the scan in 5-7 days.
An increasing body of literature is finding that non-propagating isolated calf vein thrombosis is indeed embolising to produce both 'serious' symptomatic pulmonary emboli and 'asymptomatic' pulmonary emboli that later result in pulmonary hypertension.
I refer particularly to a Scandinavian study (specifically designed to asses the source of emboli) which showed >35% of patients had an isolated calf deep vein thrombosis.1
Other studies found that 40%2 to46%3 of emboli originated in the calf. A 1993 study4 assessed patients with paradoxical emboli via patent foramen ovale; the source was isolated to calf veins in 15 of 24 patients.
While it may be contentious as to the true incidence of isolated versus propagated calf deep vein thromboses embolising, I think it is being increasingly recognised that isolated calf deep vein thromboses are not as 'benign' as was once thought. If this is true, given the potential for both symptomatic and 'asymptomatic' pulmonary emboli to have a high morbidity, should we be anticoagulating these patients rather than repeating their scan subsequently? I would be interested to hear the authors' opinion on this issue.
Emergency Department Registrar
- Havig O. Deep vein thrombosis and pulmonaryembolism. An autopsy study with multiple regression analysis of possible risk factors. Acta Chir Scand Suppl 1977;478:1-120.
- Moreno-Cabral R, Kistner RL, Nordyke RA. Importance of calf vein thrombophlebitis. Surgery 1976;80:735-42.
- Kohn H, Konig B, Mostbeck A. Incidence and clinical feature of pulmonary embolism in patients with deep vein thrombosis: a prospective study. Eur J Nucl Med 1987;13 (Suppl):11S-15S.
- Stollberger C, Slany J, Schuster I, Leitner H, Winkler WB, Karnik R. The prevalence of deep venous thrombosis in patients with suspected paradoxical embolism [published erratum appears in Ann Intern Med 1994;120:347]. Ann Intern Med 1993;119:461-5.