The purpose of this study is to determine the effectiveness of infrared thermal imaging in adjunctive diagnostic screening for lower limb deep venous thrombosis (DVT).

Inclusion Criteria:

1. Willing to participate in the trial and sign the informed consent form,
2. Aged: 18-75 years. They had been definitively diagnosed with venous thromboembolism,
3. The bed-rest immobilization time should be more than 72 hours,
4. Planing to gynecology operation,
5. The D dimer should be more than500 g • L-1,
6. There is no obvious symptoms of systemic infection two weeks before the test,
7. There is no trauma, infection, biopsy or puncture, hemorrhage and tumor in the corresponding detection site (chest and lower limbs),
8. There is no skin disease, heart, liver, kidney, gastrointestinal tract, hematopoietic system and mental, neurological has no serious diseases.

Exclusion Criteria:

1. Patients can not be good partners,
2. Doctors believe that there is any inappropriate situations.

DVT patients included in this study had been definitively diagnosed as having DVT with CPUS and/or angiography. Included non-DVT volunteers were confirmed to be without DVT with CPUS. The healthy volunteer group matched the DVT group in number, age, and gender.