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The warning signs of DVT

by – March 1, 2024

The Warning signs of DVT

As part of Deep Vein Thrombosis Month, March 2024, we thought we would explain what Deep Vein Thrombosis (DVT) is and the warning signs of DVT.

What is DVT?

DVT is an abnormal blood clot which develops within a deep vein, usually in the leg or pelvis – and is believed to affect around 1 in every 1,000 people in the UK.

Large DVTs can move from the leg or pelvic veins and go through the venous system travelling into the heart and then lungs. This is called a pulmonary embolism (PE) which is a very serious medical condition and can even be fatal.

Although most DVTs are small, harmless and resolve by themselves, it is also true that a great many DVTs never get diagnosed and are often passed off by patients, doctors, and nurses as “muscle sprains” or other leg aches. Without a venous duplex ultrasound scan performed by a specialist vascular scientist (who is able to scan even the smallest veins in the calf), one cannot be certain as to whether a DVT is present or not.

How to avoid DVT

Most people have heard of Deep Vein Thrombosis (DVT) but are surprised to learn the causes of the condition. Many people associate DVT with long haul flights and although this is a major cause there are many others which should be recognised.

If you are in hospital for an operation, your risk of getting a blood clot increases. This is because DVT is more likely to occur when you’re unwell or less active than usual. Pregnancy can also be a cause of DVT. During pregnancy, blood clots more easily. It’s the body’s way of preventing too much blood being lost during childbirth. Genetics also play a part and if a relative has previously had DVT you are more likely to have the condition too.

A Diagram showing formation of DVT

Warning signs of DVT:

The possible symptoms of Deep Vein Thrombosis can include:

  • Painful, or tender leg for no obvious reason – can be above knee, below knee or both
  • Swelling of ankle, ankle and calf, ankle, calf and thigh or even the whole leg
  • A heavy ache in the leg – especially on standing or walking
  • Warm skin in area of swelling
  • Sometimes the skin can be a bit redder, but this is less common

DVT usually affects one leg, however it can rarely affect both.

In about half of patients, there are no symptoms or ‘warning signs’ and a DVT is only diagnosed if a complication occurs.


If people are ever uncertain as to whether they are suffering from DVT or any other venous condition, it is vital that they go and see a venous specialist as soon as possible so they can carry out a duplex ultrasound scan and advise on treatment.

In many Emergency Departments, a blood test called a D-Dimer test is performed, and if positive heparin is given whilst a duplex scan is organised. However, if a duplex ultrasound scan can be performed soon, this blood test is not needed.

If DVT is diagnosed and treated immediately, in the majority of cases the clot will be dissolved, and the vein will return to normal. If three is a delay in diagnosis and treatment, or if there are recurrent DVTs in the same leg, the deep veins can become scared and stop working properly. This causes “post-thrombotic syndrome” (PTS) which can cause chronic pain and swelling of the leg, with discolouration and often leg ulcers.

However, with very severe cases, the clot may have to be removed under X-ray control, although this is a very uncommon procedure currently.

It is also important to know why the clot has formed. This can be due to varicose veins, a compression in the veins, changes in the blood (dehydration, smoking and some drugs) or blood flow, or even a sign of other disease including abnormal blood clotting. Long flights and immobility are also contributory factors.

After the DVT has been diagnosed and treated, it is essential to look for the underlying cause and treat it, to reduce the risks of further DVTs in the future.

If you are concerned that you have DVT and would like to book a consultation please call The Whiteley Clinic on 0330 058 1850 or contact us by clicking here.

The contents of this site are for informational purposes only and are meant to be discussed with your doctor or other qualified health care professional before being acted on. Always seek the advice of a doctor or other licensed health care professional regarding any questions you have about your medical condition(s) and treatment(s). This site and the information provided is not a substitute for medical advice.