A 35-year-old woman is suffering pain and swelling in her right leg. She said her symptoms began 2 days ago, as she was getting off a plane after a 13-hour flight from overseas. Her symptoms have gradually increased since that time. She denies left leg complaints, shortness of breath, or chest pain. Past medical history is insignificant, and the patient's only regular medication is oral contraceptive pills. The patient smokes 1 pack of cigarettes per day.
T: 100.8°F BP: 132/86 RR: 12/min. P: 72/min.
The patient is obese, but in no acute distress. Her right leg below the knee is edematous, enlarged, mildly erythematous, and quite warm to the touch when compared to the left. The calf is also tender to palpation. A hard cord is palpable deep within in the popliteal fossa. With the knee flexed, forceful dorsiflexion of the knee causes severe calf pain. The rest of the physical exam is normal.
Hemoglobin: 13 mg/dL (normal 12-16)
White blood cell count: 8400/μL (normal 4500-11,000)
Platelets: 330,000/μL (normal 150,000-400,000)
Creatinine: 0.9 mg/dL (normal 0.6-1.5)
Sodium: 142 meq/L (normal 135-145)
Potassium: 3.9 meq/L (normal 3.5-5)
Deep venous thrombosis (DVT)
In this patient, the DVT is likely of the popliteal vein.
DVT is primarily of concern because it can lead to pulmonary embolus (PE) and chronic venous insufficiency. The risk factors are summarized by Virchow's triad: endothelial damage (e.g., trauma, infection), stasis of blood flow (e.g., immobilization, long airplane flight or car ride, major surgery, heart failure, obesity), and hypercoagulable state (e.g., oral contraceptives, genetic tendencies, malignancy, pregnancy).
Diagnosis & Treatment
Classic symptoms include pain, swelling, increased temperature, and skin erythema. Patients often have one or more risk factors for DVT. Symptoms may come on gradually over a few days.
Physical findings are unreliable, but may include the above plus calf/leg tenderness, a palpable cord in the region of a deep vein, and Homan's sign (dorsiflexion of the ankle with the knee flexed causes calf pain). Enlarged collateral veins may be seen in the leg in some cases. The D-dimer may be positive, but this is not specific and can be found in normal people. Symptoms and signs of PE may be present. The diagnosis is generally made with imaging, usually a Doppler venous ultrasound. Impedance plethysmography, standard venography, and magnetic resonance venography are other diagnostic options.
Treatment is anticoagulation with either standard or low-molecular-weight heparin and warfarin. Once warfarin causes prothrombin time prolongation (measured using the international normalized ratio [INR], with a goal level of roughly 2 to 3 times normal), the heparin product can be stopped. Anticoagulation is generally advised for at least 3-6 months after the first episode and indefinitely if a second episode of DVT occurs. Any modifiable DVT risk factors should also be addressed (e.g., stop the oral contraceptive pills). In those who are not anticoagulation candidates for any reason, a metal filter (e.g., Greenfield filter) can be placed inside the inferior vena cava to prevent PE.
More High-Yield Facts
The inherited causes of a hypercoagulable state include factor V Leyden, thrombin variant, and antithrombin 3, protein C, and protein S deficiency. These should be tested for in all patients without an obvious cause of DVT. Those who are positive often need permanent anticoagulation.
A superficial palpable cord is due to superficial thrombophlebitis (not DVT), which does not lead to PE. Treat with aspirin and local heat