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Medical abbreviation:

None

Type:

Radiology

Definition:

Contrast venography involves injecting radio-opaque (shows up on x-rays) dye into the veins of the leg (most commonly). In cases involving the veins of the legs or arms a tourniquet may be applied to help encourage blood flow and hence uptake of the dye into the deeper veins.

When would I need this test?

The test is used when doctors need to exclude a blockage in any vein. Its most common application is used to exclude deep vein thrombosis (usually in the lower leg), in cases where compression ultrasound is unable to confirm or exclude the diagnosis of DVT. Contrast venography is regarded as the gold standard test for diagnosis, but is invasive as it involves injecting dye (contrast) into the veins, before x-rays can be taken.

Important

Compression ultrasound is the fastest and safest way to diagnose DVT, with accuracy figures as high as 95%. Contrast venography is reserved for cases where compression ultrasound is unable to give a reliable answer.

Risks

The potential risks of contrast venography are:

• Pain at the site of injection of the dye
• Infection at the site of injection of the dye
• Leakage of dye into the skin
• Skin ulceration at the site of injection
• Inflammation of the veins due to the dye
• Kidney failure due to dye (rare)
• Severe allergic reaction to the dye (rare)
• Pulmonary embolism due to squeezing of the suspected clot (rare)