Patients who are newly diagnosed with deep vein thrombosis (DVT) often have questions relating to the possibility of clot migration to the lungs. After anticoagulants are started, the clot may dissolve on its own or remain in the leg indefinitely (chronic DVT). Once the clotting cascade is interrupted by the anticoagulants, the clot usually begins to shrink and becomes firmly attached to the vessel wall. With time, the lining of the vessel wall may grow over the clot. Once the clot has become attached to the wall of the blood vessel and the lining of the blood vessel has grown over it, there is a much lower risk of the clot moving and/or causing more clot formation. This process is thought to take about 5 to 10 days. It is also possible that the body's own mechanism for dissolving clots may slowly eliminate the clot.

Some clinicians recently have started to use ultrasound scanning to determine if a clot remains at different points in the treatment process. At least one study has suggested that if the clot disappears completely, then the patient is less likely to have another clot once treatment is stopped.

Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.