A young woman presents to her podiatrist office with pain and swelling in her calf. She was seen two weeks prior and was found to have a fractured bone in her foot. To treat this condition, she was given a CAM boot (walking cast) to stabilize the fracture. Current medications she is taking include oral contraceptives (birth control pills). What is the cause of her pain?
Definition of Deep Vein Thrombosis (DVT)
The ability of blood to clot plays a major role in healing. Upon injury that causes bleeding, platelets and fibrin clump together to form a durable barricade to blood flow. This prevents loss of blood from the body and facilitates the healing process. However, this process can occur at times that are unnecessary, resulting in an unwanted blockage of blood flow in blood vessels. A common site for blood clotting gone awry is the deep vein of the calf.
Deep vein thrombosis, or DVT, occurs when a blood clot forms in the deep vein of the calf. You may have heard about episodes of DVT caused by sitting or lying down for a long period of time, such as on an airplane or in a hospital bed. A long period of immobility slows down blood flow through the veins, which is a major risk factor for clot formation. DVT can also occur after surgery due to damage to the venous vessel wall.
Hypercoagulability of blood is another reason why DVT can arise. Hypercoagulability is a state of excessive clotting in the blood, and could possibly be the reason why the patient in the above example presents to the clinic today. Supplemental estrogen from contraceptive use can increase the coagulability of blood. Notice also that the patient arrived in a CAM walker, which rendered her immobile for a considerable period of time and furthered her risk of developing DVT.
Other risk factors include pregnancy, smoking, or genetic conditions like thrombophilia.
A patient with DVT can present with pain in one leg that gets better when the leg is elevated. Redness, swelling and tenderness are other symptoms to take into account. It should be noted, however, that a patient with DVT might not experience symptoms at all.
A major concern for development of DVT is the potential for portions of the clot to break off, forming an embolus. An embolus flows through the blood and can lodge itself in a downstream location. A pulmonary embolism is a dangerous complication that occurs when a portion of the clot breaks and gets stuck in an artery in the lungs. Symptoms of pulmonary embolism include a sudden shortness of breath and cough. Patients experiencing these symptoms should immediately visit the emergency department. This condition can be life threatening!
When a podiatrist suspects a DVT, there are certain simple physical test that can be performed as screening tools. Some patients may exhibit pain when their foot is extended towards the ankle, eliciting a positive Homan’s sign. A positive Bancroft’s sign is observed when the patient experiences pain when the doctor squeezes their calf from the front and back. Neither of these tests can absolutely confirm that a DVT is present, but can certainly aid in diagnosis when combined with patient history and further diagnostic testing.
Use of a duplex ultrasound is a sure-fire way to confirm diagnosis of DVT. This noninvasive procedure measures the blood vessels in the patient’s calf for irregularities in flow. A thrombus is present when blockage of flow is observed.
A d-dimer test can also be used. D-dimer is a fragment of fibrin, one of the molecules involved with building a robust clot in blood vessels. Blood is drawn from the patient and the level of d-dimer is measured. If measured level is high, indicating a positive test, then further testing can be done to confirm DVT. This test is usually used when there is a low probability that the patient has DVT because a negative test rules it out.
The importance of treating DVT, even if it is asymptomatic, is to prevent the occurrence of more lethal complications such as a pulmonary embolism. Anticoagulants can be prescribed for the purpose of achieving this goal by dissolving the clot or preventing it from growing larger. These medications include injections of Low Molecular Weight Heparins (LMWH) or oral Coumadin.
Prophylactic measures can also be taken in patients that are at risk of developing DVT. Compression stockings can be used on patients who are bedbound for a long period of time. Anticoagulants can also be used prophylactically. It is important to advise patients who have had previous episodes or are at risk of clotting to not stay seated for too long when flying long distances since this can cause development of DVT.
If you are reading this because you think that this might be what is causing your calf pain….call 911 or go quickly to the nearest emergency room!