Guildford   London   Bristol

Tests for DVT


Testing for DVT

The Whiteley Clinic only use gold standard testing to diagnose DVT – a duplex ultrasound scan performed on a high resolution machine by our own trained vascular scientists working to The Whiteley Protocol®. All of our vascular scientists scan veins regularly and are experts in all aspects of venous scanning. To make sure no DVT goes unmissed, all veins are checked from groin to ankle and often even into the pelvis. We would never use the quick alternative that is often used by doctors or clinics as a quick screening test which only takes a few minutes and is quite likely to miss significant DVT.

We do not specify how long treatment should last. Instead, we use venous duplex ultrasound scanning to tailor the treatment that each patient needs, which is dependent on how well they are responding to anticoagulation. By doing this, we have often avoided stopping Warfarin too soon (when clot is still present), or avoided stopping it in patients who have narrowed veins who should stay on the Warfarin to prevent further DVTs.


When DVT is suspected, a variety of tests are used to screen for it:

  • Venography – An X-ray with contrast injected into the foot – now out of date and not needed
  • Thermography – an infra-red device is used to see if the leg is warmer than the other – quite inaccurate and useless if both legs have DVTs!!
  • Blood test – tests checking for signs of clots in the blood are simple to perform, and although often right do sometimes give the wrong results. This means either patients get treatment they don’t need until a specialist scan is done, or get sent home with a DVT
  • Duplex Ultrasound scan – this is the gold standard – but only if done by a specialist who checks from pelvis to ankle (taking 30 mins +). Many non-specialists or doctors or nurses who have “been on a course” will be able to see a massive DVT in the thigh, but will often miss small DVTs in the lower leg, where the veins are tiny.
  • Treatment is usually with Heparin injections then oral Warfarin tablets. The level of anti-coagulation (clotting level) is regularly checked with the INR blood test. Warfarin is usually stopped 3 or 6 months after the diagnosis of the DVT.

A painful swollen leg is the commonest presentation of a deep vein thrombosis (DVT). However many other things cause painful swollen legs and also some DVTs present without pain, or without swelling. Therefore, before we think about treatment of DVT, we have to make sure that we are treating a deep vein thrombosis and nothing else instead.


Blood tests for DVT

There are some blood tests that are used in accident and emergency departments for screening for deep vein thrombosis (DVT). These rely on picking up the biochemical markers of clotting somewhere inside the circulatory system.

An argument can (and has) been made for these tests as a screening test to put people into a high risk” or “low risk” category of having a DVT. this is useful in a public service that has a lot of people to see and where costs have to be contained. However, these are not highly accurate and so in an individual who wants tohave the optimal treatment, there is really no place for them.

Duplex Ultrasound scan

The best test currently available for diagnosing deep vein thrombosis (DVT) is a colour flow duplex ultrasound performed by a specialist. There are several different sorts of colour flow duplex ultrasound and to be able to diagnose small deep vein thromboses in the calf, a very high resolution machine is required operated by someone who is expert in scanning veins.

At The Whiteley Clinic we insist on the very best equipment and train our own vascular scientists to make sure that they reach the exacting standards that we insist upon.