Deep Vein Thrombosis is a part of a group of disorders which are collectively referred to as Venous Thromboembolic Diseases (VTE) . This group of disorders are characterized by formation of blood clots, abnormally, in the veins, arteries or the chambers in the heart. Worldwide, there are approximately 10 million cases every year.
DVT specifically refers to the abnormal clot formation in the veins. Patients with DVT may have various symptoms depending upon the veins involved; individuals with DVT of the veins in the calf may complain of cramps which intensify over several days. Other possible complains are pain, redness, swelling and warmth in the affected limb.
Causes of DVT
DVT can be caused by events which either lead to prolonged immobilization of a limb or an increase in the tendency of the blood to coagulate or cause damage to the inner lining of the vein. Prolonged immobilization of a limb occurs in individuals whose limb has been in a cast or has been bedridden for an extended time interval. There are many conditions which may cause an increase in the tendency of the blood to coagulate; these range from genetic disorders affecting clotting factors to malignancy, infections, some medications, and surgery.
Symptoms and Signs of DVT
Individuals with DVT may have complains of pain, redness, swelling, and a mild increase in temperature in the affected limb. DVT in the calf may lead to an experience of a cramp in the leg which intensifies over time. Many patients though have no complains and are asymptomatic.
Diagnosis of DVT
The diagnosis of DVT is done by the combination of examination by the doctor and tests. Some of the tests done are:
Plasma D-Dimer ELISA: It is a blood test which measures the levels of D-Dimer in the blood; elevated levels may be attributed to DVT. This test is a useful rule out test i.e. a normal test result indicates that DVT is absent but a positive test result does not necessarily mean that the individual has DVT.
Venous compression Ultrasonography: The sonographer examines the veins in the affected leg or arm. Normal veins are easily compressible but veins with thrombosis aren’t; the sonographer differentiates between these two types of veins by applying gentle pressure on the suspected vein and looking for their compressibility.
Complications of DVT
Pulmonary Embolism: The major complication seen in individuals with DVT is Pulmonary Embolism(PE). About half of the untreated DVT patients go on to develop PE. Patients with PE experience sudden onset shortness of breath accompanied by chest pain which worsens with breathing movements, blood in sputum and increased heart rate; these symptoms are a medical emergency and an individual experiencing them ought to see their physician as soon as possible.
Post thrombotic syndrome(PTS) which is seen in half of the untreated DVT patients. PTS is caused due to damage to the valves in the veins, because of the clot formed due to the DVT. Damaged valves allow the blood to flow back which leads to pooling of the blood in the extremity, this may cause redness, pain and swelling. When early symptoms of PTS are ignored they may proceed to the development of ulcers and pigmentation and itching in the limb involved.
Treatment of DVT
The treatment for DVT aims to prevent recurrence and reduce further complications due to DVT and the therapy itself. Generally the initial treatment of DVT consists of:
Anticoagulation therapy (Blood thinners) with intravenous or subcutaneous drugs like unfractionated heparin(UFH) or low molecular weight heparin(LMWH) or fondaparinux. Oral drugs like warfarin or dabigatran or rivaroxaban are also prescribed by the physician to prevent recurrence. The current guidelines recommend atleast three months of anticoagulation therapy for individuals with first episode of VTE.
IVC Filter: When there is an absolute contraindication for the use of anticoagulants, the patient may be advised to have an Inferior Vena Cava(IVC) Filter; this will help in preventing PE, a major complication of DVT.
Non-pharmacological treatments for DVT include leg elevation, to reduce swelling in the leg; ambulation, to prevent stasis of blood, but strenuous exercise are to be avoided initially; and graduated compression stocking which prevent swelling but do not treat DVT.
Prognosis of DVT
Lower extremity DVT when left untreated may cause massive PE in about 3% of individuals. The probability of recurrence of DVT is the least in individuals with transient risk factors like surgery, cast or trauma; while the opposite is true for individuals with persistent risk factors like cancer. A Normal D-Dimer value after warfarin therapy is stopped indicates low risk of DVT recurrence.