Definition & Overview

Bilateral deep venous thrombosis (DVT) refers to the condition wherein a blood clot forms within the deep vein of both legs causing pain, swelling, and redness. This condition can lead to serious complications including pulmonary embolism, or when the clot detaches and travels to the lungs.

People who are found to have an increased risk of developing DVT should undergo screening so life-threatening conditions can be avoided.

Who Should Undergo and Expected Results

The screening is recommended for those who are at risk of developing bilateral deep vein thrombosis and these include:

  • Those who are older than age 40
  • Those with a family history of deep vein thrombosis and pulmonary embolism
  • Overweight or obese individuals
  • Those who need but are not taking anticoagulant medicines as prescribed
  • Those who suffer from conditions that slow blood flow, such as leg paralysis
  • Those who have undergone major surgical procedures followed by a prolonged recovery period and best rest
  • Those who suffer from a blood vessel injury
  • Patients suffering from blood diseases, such as congenital blood clotting problems
  • Patients suffering from blood vessel diseases, such as varicose veins, heart failure, stroke, or heart attack
  • Pregnant women
  • Patients under hormone therapy
  • Women using birth control pills or patches
  • Smokers
  • Cancer patients or those who have an active malignancy
  • Those who undergo certain cancer treatments such as chemotherapy and radiotherapy
  • Patients suffering from thrombophilia, Hughes syndrome, and heart and lung diseases
  • Recent traumatic injury to the legs, brain, hips, or abdomen

A normal result of bilateral DVT screening means that there is no narrowing or obstruction in the deep veins of the legs. An abnormal result, on the other hand, will show some degree of narrowing of the said veins or the presence of a blood clot in both legs. This means that the patient will be diagnosed with bilateral DVT.

How is the Procedure Performed?

A duplex ultrasound can be used to scan blood vessels, such as arteries and veins. However, for the purpose of diagnosing bilateral deep venous thrombosis, a venous scan is necessary. For this procedure, the patient will be asked to wear a medical gown and to lie down on an examination table. The ultrasound technician will then spread a special gel-like substance, which will carry the sound waves into the tissues, over the patient’s legs.

The technician will then place a transducer against the leg, moving it all over the area. The transducer sends out the sound waves, and as it enters the tissues, the waves reflect back, and the data is sent to a computer monitor wherein it forms images. The same procedure, which is similar to a regular ultrasound scan, is performed on the other leg.

During the scan, the patient will be asked to stay still to ensure the accuracy of the images. It may also be necessary to move to different leg positions to screen all parts of the legs.

Possible Risks and Complications

A venous duplex ultrasound scan, like a regular ultrasound scan, is guaranteed safe for use in diagnosing medical conditions. The procedure is not known to cause any discomfort or harmful effects because the amount of ultrasound energy used is very minimal and conforms to international standards.

Nevertheless, due to the risk of radiation exposure, patients are advised to have the scan performed only by trained and certified ultrasound technicians.


  • De Oliveira A., Franca GJ., Vidal EA., et al. “Duplex scan in patients with clinical suspicion of deep venous thrombosis.” Cardiovasic Ultrasound. 2008 Oct 20;6-53.

  • Chua K., Kong KH, Chan SP. “Prevalence and risk factors of asymptomatic lower extremity deep venous thrombosis in Asian neurorehabilitation admissions in Singapore.” Arch Phys Med Rehabil. 2008 Dec;89(12):2316-23.

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