Nontreatment of deep vein thrombosis

Douketis, James D.

Drs Katz and Rapoport-Glick raise an important issue that has not been addressed in most clinical trials investigating the treatment of DVT: management of patients who present with lower limb swelling or pain and are diagnosed with DVT of the distal (or calf) veins. This issue is seen increasingly in clinical practice with improved venous ultrasound techniques that can, in many patients, show the distal as well as the proximal (above-knee) deep venous system.¹

Several questions relating to the management of distal DVT deserve comment. First, should all patients with distal DVT receive anticoagulant therapy, as in patients with proximal DVT? Second, if anticoagulants are given, what is the optimal duration of treatment? Third, do such patients warrant additional investigations, such as looking for thrombophilia or occult cancer, as might be the case in some patients with proximal and, in particular, unprovoked (or idiopathic) DVT?

In general, patients who have symptomatic DVT, whether proximal or distal, warrant conventional anticoagulant therapy with low-molecular-weight heparin and warfarin.² Without anticoagulant therapy, patients with symptomatic distal DVT have about a 20% chance that the DVT will extend into the proximal veins, which could cause life-threatening pulmonary embolism.³ Furthermore, anticoagulant therapy helps to alleviate leg pain and swelling that can be severe, even in patients with less extensive distal DVT. However, in patients with superficial vein thrombophlebitis that does not involve the deep veins, initial treatment with a nonsteroidal anti-inflammatory drug or a 2- to 4-week course of a low-dose heparin preparation could be considered.² There is no consensus on the optimal duration of anticoagulation for distal DVT, although a 3-month course is reasonable, assuming that symptoms have resolved and there are no ongoing risk factors for disease recurrence, such as active cancer or immobility.⁴

Finally, as to whether further investigation to assess etiology is warranted in such patients, the key point perhaps is that DVT is a single disease and the same management principles should apply, whether DVT is proximal or distal. Thus, thrombophilia testing would be reasonable in patients with unprovoked DVT, particularly if they are young (<50 years) and have a personal or family history of venous thromboembolism. A workup for occult cancer would depend on associated clinical features, such as a change in bowel habits in elderly patients, which might suggest a tumour site, or the presence of risk factors, such as heavy smoking.

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