Should symptomatic, isolated distal deep vein thrombosis be treated with anticoagulation?

BACKGROUND: During the past two decades, the diagnosis of deep venous thrombosis (DVT) has made considerable progress. The term distal or calf vein thrombosis includes thrombosis in infrapopliteal veins, including the posterior tibial, peroneal, anterior tibial and muscular calf veins. The necessity of treating of distal DVT is debatable.

OBJECTIVE: To determine whether treatment of isolated, distal DVT with anticoagulation versus no treatment affects patient outcome.

METHODS: All patients discharged with a diagnosis of distal DVT from Tan Tock Seng Hospital, Singapore, between January 1, 2006, and December 31, 2007, were identified by the medical records office of the hospital. Compression of the intraluminal thrombus by duplex scan was used to diagnose distal DVT. Excluded were patients who either had both distal and proximal DVT, or had distal DVT along with pulmonary embolism (PE) at presentation. Complete resolution of distal DVT on repeat duplex scan was used to measure the primary outcome. Repeat follow-up scans were performed at two weeks, one month, three months and six months, or on subsequent follow-up until the distal DVT had resolved completely. Secondary outcome measures were complete improvement of symptoms, progression of thrombosis, or PE or death during the follow-up period. The study included 68 patients with distal DVT; however, 17 patients with PE, two of whom had proximal DVT (in the iliac and common femoral veins) at the first presentation along with distal DVT, were excluded from the study. In total, 51 patients were included for analysis. The follow-up scan was available in 35 patients; therefore, the primary analysis was performed in 35 patients (47 incidences of distal DVT). However, the secondary analysis was available in all 51 patients. Of the 35 patients available for follow-up scans, 17 patients (25 incidences of distal DVT) received anticoagulation and 18 patients (22 incidences of distal DVT) received no anticoagulation. Of the 17 patients who were treated with anticoagulation, nine patients (13 incidences of distal DVT) received enoxaparin at a dose of 1 mg/kg twice a day for two weeks and eight patients (12 incidences of distal DVT) received warfarin for a period of three months with initial overlap of enoxaparin 1 mg/kg twice a day for three to five days. Once the prothrombin time international normalized ratio of a patient on warfarin was between 2 and 3, enoxaparin was discontinued. The 18 patients who did not receive anticoagulation received follow-up with regular duplex scan.

RESULTS: There were no statistically significant differences among the groups in the resolution of distal DVT or symptom improvement with or without treatment. In the group that received no treatment, one death occurred. Proximal extension and PE were not recorded in any of the patients.

CONCLUSION: Distal DVT may not require treatment with anticoagulation. If leg symptoms worsen, or if there is an extension of distal DVT on the follow-up scan, treatment with anticoagulation is recommended.