The typical symptoms of deep venous thrombosis are a swollen extremity, typically of new-onset. Unilateral swelling, especially in context of recent surgery is the most specific symptom. Sometimes, the extremity is not only swollen, but it might be red and warm. Many times, there are no symptoms, except from shortness of breath due to P.E. Leg pain is also not always present. If leg pain and swelling is present in the case of DVT, it does not necessarily correlate with the site of the blood clot. Significant edema with bluish discloration of the foot (phlegmasia cerulea dolens) is rare, and needs to be treated aggressively.
On physical examination, there is no accurate way of diagnosing deep venous thrombosis. The best way of diagnosing this problem is to suspect it in the clinical situation, and perform a Doppler ultrasound test of the extremity. In general, some of the physical examination findings of DVT will include edema and tenderness. The old standard of Homans sign, which was pain in the calf muscles with flexing the foot downward does not correlate well with the presence of a DVT. Distension of the superficial veins, and superficial phlebitis are sometimes found concomittantly with deep venous clots. An acute thrombosis is also one of the causes of early low grade fever after surgery.
DIAGNOSIS
The diagnosis of deep venous thrombosis is more dependent on clinical suspicion and diagnostic testing than any other factor. Acute shortness of breath, swelling in the limb after surgery, pain in the limb following injury are just some of the signs that might alert the clinician to suspect a deep venous thrombosis. However, Doppler ultrasound is the diagnostic test of choice, and should be used liberally if there is a suspicion of deep venous thrombosis. Although not 100% fool-proof, Doppler ultrasound is a non-invasive and simple test to perform to evaluate for a blood clot. There are other screening tests being performed, such as a blood test called a D-dimer test, but none of these other modalities are as reliable as Doppler ultrasound in the hands of a technologist and medical specialist who reviews many studies.
RISK FACTORS
There are many risk factors for deep venous thrombosis, and numerous attempts are made to stratify these risks. The importance of these risks really lies in attempts to understand who is at higher risk for a deep vein clot, and when to treat them prophylactically, especially while they are hospitalized in order to reduce the chance of a DVT. Some of the risks are detailed below.
- Age
- Immobilization longer than 3 days
- Pregnancy and the postpartum period
- Major surgery greater than 45 minutes in duration
- Long plane rides or car trips
- Cancer
- Previous history of DVT
- Stroke
- Acute heart attack
- Congestive heart failure
- A kidney condition of where one loses large amounts of protein in the urine, called Nephrotic syndrome
- Ulcerative colitis
- Major trauma and broken bones
- Head injury
- Systemic lupus erythematosus (SLE)
- Behçet syndrome
- Homocystinuria
- Polycythemia rubra vera (high hemoglobin level)
- Thrombocytosis (high platelet count, the particles in the blood that actually clot)
- Antithrombin III deficiency ( a protein that tries to prevent clotting that occurs in the body)
- Protein C deficiency ( another protein that tries to prevent clotting that occurs in the body
- Protein S deficiency ( another protein that tries to prevent clotting that occurs in the body
- Factor V Leiden
- Prothrombin 20210 mutation
- Activated protein C resistance
- Oral contraceptives
- Heparin-induced thrombocytopenia
- Other clotting disorders
TREATMENT OPTIONS
Once the diagnosis of a deep vein clot is made, then the first treatment choice is to start anticoagulation. The current medication of choice is Lovenox at a dose of 1 mg/kg of body weight, twice daily given as a subcutaneous injection. After Lovenox has been initiated, then an oral blood thinning agent, Warfarin (Coumadin), is started. Lovenox acts quickly to thin out the blood, while Warfarin takes 3-5 days to reach its full effect. The dose of Warfarin has to be adjusted depending on a blood test called the Protime with INR, or PT with INR. Essentially, the goal level of blood thinning is to achieve an INR of 2.0-2.5. At that time, the Lovenox can be discontinued. Other potential medications that can be used for blood thinning include Heparin, which was the old standard. However, the blood thinning effects of heparin have to be adjusted based a a blood test, and it is given through the vein or with shots, and therefore is not as convenient as Lovenox.
Recent studies have shown that deep venous thrombosis can be treated safely as an outpatient by initiating Lovenox and Warfarin therapy. Some clinicians still prefer to admit patients to the hospital for initiation of blood thinning, given the potential for PE.
The main point of blood thinning is to prevent enlargement of the blood clot, and to stablilize it, so that it does not break of and go to the lungs as a PE. The blood clot itself can either dissolve over time, or become chronic clot (scar tissue),or it can reform a channel though the clot where vein blood can flow back towards the heart. Either way, the treatment choice remains blood thinning for 3-6 months. If one has recurrent episodes of DVT, then a year or even lifetime blood thinning with Warfarin might be indicated.
In the event that blood thinning is contraindicated, then the alternative is to place a device in the main vein draining the legs to reduce the chances of blood clots breaking off and going to the lungs. This device is called an inferior vena cava filter, and can be either temporary (removable) or permanent.
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