Testing for deep vein thrombosis 

Your doctor will ask you about your medical history and your symptoms. However, it can be difficult to diagnose DVT from symptoms alone, so your doctor may recommend one of the following tests:

D-dimer test

A specialised blood test, known as the D-dimer test, is used to detect pieces of blood clot that have been broken down and are loose in your bloodstream. The larger the number of fragments found, the more likely it is that you have a blood clot in your vein.

Ultrasound scan

An ultrasound scan can be used to detect clots in your veins. A special type of ultrasound, known as a Doppler ultrasound, can also be used to find out how fast the blood is flowing through a blood vessel. This helps doctors to identify when blood flow is slowed or blocked, which could be caused by a blood clot

Venogram

If the results of a D-dimer test and ultrasound scan cannot confirm a diagnosis of DVT, a venogram might be used. 

A special dye is injected into a vein in your foot, which travels up the blood vessels of your leg. An X-ray is taken to see the dye. If there is a blood clot in your leg, the dye will not be able to flow round it and will show up as a ‘gap’ in your blood vessel.

Doppler study

A Doppler study is used to measure the supply of blood to each of your legs, which is then compared with a measurement of the blood pressure in your arm.

When the measurements are compared, they can show whether the blood supply in your legs is reduced.

Available treatments 

If you have deep vein thrombosis (DVT) you will need to take a medicine called an anticoagulant.

Anticoagulation

Anticoagulant medicines prevent a blood clot from getting bigger. They can also help stop part of the blood clot from breaking off and becoming lodged in another part of your bloodstream (an embolism).

Although they are often referred to as ‘blood-thinning’ medicines, anticoagulants do not actually thin the blood – they alter chemicals within it, which prevents clots forming so easily.

Two different types of anticoagulants are used to treat DVT:

• heparin and
• warfarin

Heparin is usually prescribed first, because it works immediately to prevent further clotting. After this initial treatment you may also need to take warfarin to prevent another blood clot forming.

Heparin

Heparin is available in two different forms:

• standard (unfractioned) heparin and
• low molecular weight heparin (LMWH).

Both forms of heparin are given intravenously (IV), straight into one of your veins.

Standard (unfractioned) heparin is fed into the vein through a narrow tube (intravenous line) and must be given in hospital. A dose of standard heparin can work differently from person to person, so the dosage must be carefully monitored and adjusted where necessary. You may need to stay in hospital for five to 10 days and have frequent blood tests to ensure you receive the right dose.

LMWH works slightly differently from standard heparin. It contains small molecules, which means its effects are more reliable and you will not have to stay in hospital and be monitored.

Both standard and LMWH can cause side effects, including:

• a skin rash and other allergic reactions
• bleeding and
• weakening of the bones (if taken for a long time).

In rare cases, heparin can also cause an extreme reaction that makes existing blood clots worse and causes new clots to develop. This reaction, and weakening of your bones, is less likely to occur when taking LMWH.

In most cases, you will be given LMWH because it is easier to use and causes fewer side effects.

Warfarin

Warfarin is taken as a tablet. You may need to take it after an initial heparin treatment to prevent further blood clots occurring. Your doctor may recommend that you take warfarin for three to six months. In some cases, warfarin may need to be taken for longer, even for life.

As with standard heparin, the effects of warfarin vary from person to person, and you will need to be closely monitored with frequent blood tests to ensure you are taking the right dosage.

When you first start taking warfarin, you may need to have two to three blood tests a week until your regular dose is decided. After this, you should only need to have a blood test every four weeks at an anticoagulant outpatient clinic.

Warfarin can be affected by your diet, any other medicines that you are taking, and by how well your liver is working. If you are taking warfarin, you should:

• keep your diet consistent
• limit the amount of alcohol that you drink (no more than three to four units a day for men and two to three units a day for women)
• take your dose of warfarin at the same time every day
• not start to take any other medicine without checking with your GP, pharmacist or anticoagulant specialist and
• not take herbal medicines.

Warfarin is not recommended for pregnant women. Instead, heparin injections are given for the full length of anticoagulation treatment.

Compression stockings

Compression stockings help prevent calf pain and swelling and lower the risk of ulcers developing after having a DVT. They can also help prevent post-thrombotic syndrome – damage to the tissue of your calf caused by the increase in blood pressure that occurs when a vein is blocked (by a clot) and blood is diverted to the outer veins.

After having a DVT, stockings should be worn every day for at least two years because symptoms of post-thrombotic syndrome may develop several months, or even years, after having DVT.

Compression stockings should be fitted professionally. They need to be worn all day, but can be taken off before going to bed or in the evening while you rest with your leg raised.

Raising your leg

As well as wearing compression stockings, you might be advised to raise your leg whenever you are resting. This helps to relieve the pressure in the veins of the calf and stops blood and fluid pooling in the calf itself.

When raising your leg, make sure that your foot is higher than your hip. This will help the returning blood flow from your calf. Putting a cushion underneath your leg while you are in a reclining position should help raise your leg above the level of your hip.

You can also slightly raise the end of your bed to ensure that your foot and calf are slightly higher than your hip when you are asleep.

Related posts:

1. Causes of Deep Vein Thrombosis (DVT)
2. Blood Clot: Deep Vein Thrombosis