The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

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.

Rob Ojala
Emergency Department Registrar
Melbourne, Vic.

Authors' comments

Dr J.C. Tay and Dr M. McGrath, authors of the article, comment:

Dr Rob Ojala's correspondence highlights one of the current controversies in the management of deep vein thrombosis. As yet, there is insufficient evidence to be dogmatic about management of the isolated calf vein thrombosis, although we would support Dr A.S. Gallus' recommendation about the treatment of symptomatic calf vein thrombosis (Aust Prescr 1998;21:64-6). The emphasis of our review was to describe the diagnostic test options. The value of colour duplex ultrasonography is to provide a means of ongoing non-invasive surveillance of the deep vein thrombosis. This is of particular relevance if a decision is made not to include anticoagulation in managing an asymptomatic isolated calf vein thrombosis.


  1. 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.
  2. Moreno-Cabral R, Kistner RL, Nordyke RA. Importance of calf vein thrombophlebitis. Surgery 1976;80:735-42.
  3. 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.
  4. 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.