Deep vein thrombosis | DVT or poketoto

Blood clots

Deep vein thrombosis (DVT or poketoto) occurs when a blood clot forms in a deep vein in your body, usually in your legs.

Veins are blood vessels that carry blood from the tissues of the body back to your heart. A DVT (deep vein thrombosis) is a blood clot that occurs in the deep veins. The most common veins to be affected are those in your legs.

The blood clot can dislodge out of the vein and travel elsewhere in the body and this is called an embolus. If the embolus travels and gets stuck in the lungs this is called pulmonary embolism and is the most serious complication from DVT. 

Image credit: Deep vein thrombosis, NHS

What are the symptoms of DVT?

A DVT can occur in any limb but tends to occur more commonly in the leg – involving the foot, ankle, calf or whole leg.

Signs and symptoms can include:

  • Swelling in the affected limb. Rarely, there may be swelling in both legs. This is from the blood collecting behind the clot.
  • Pain in your leg. The pain often starts in your calf and can feel like cramping or a soreness.
  • Change of colour in the leg – bluish, purple or reddish skin colour.
  • Feeling of warmth on the skin of the painful or swollen area.   

These symptoms may often be confused with a sprained ankle or other injury. DVT can sometimes occur without any noticeable symptoms. If you develop signs or symptoms of DVT, contact your doctor urgently.

Sometimes blood clots can form in the veins that are closer to the surface of the skin, called the superficial veins. A clot in one of these veins is called superficial thrombophlebitis. It is not as worrying as a DVT because it can’t travel to the lungs. They also cause different symptoms to DVTs. Superficial clots are more painful and cause redness or even infection. They cause the veins to become hard and bulge out making them look like cords. This is most commonly seen below the knee.

Seek immediate medical help if:

You have symptoms of DVT, such as pain and swelling, and:

• breathlessness
• chest pain.

These symptoms could mean you have a pulmonary embolism. A pulmonary embolism can be life threatening and needs treatment straight away.

Call Healthline on 0800 611 116 if you are unsure about what to do.

Who is at risk of developing DVT?

Many factors can increase your risk of developing DVT. The more risk factors you have, the greater your risk.

A DVT is more likely to happen if you:

  • are over 60 years of age
  • are overweight
  • smoke
  • have had a DVT before
  • take the contraceptive pill or HRT (hormone replacement therapy)
  • have cancer or heart failure
  • have varicose veins.

There are also some temporary situations when you're at more risk of DVT. These include if you:

  • are staying in or recently left hospital – especially if you cannot move around much (like after an operation)
  • are confined to bed
  • go on a long journey (more than 4 hours) by plane, car or train
  • are pregnant or have had a baby in the previous 6 weeks
  • are dehydrated.

How is DVT diagnosed?

If you suspect you have a DVT, even if you have mild symptoms, you must seek medical attention urgently. This can prevent serious complications such as a pulmonary embolism.

To diagnose DVT, your doctor will ask you questions about your symptoms. You may also have a physical exam to check for any areas of swelling, tenderness or discoloration on your skin.

Your doctor may suggest further testing, such as a D-dimer blood test and/or an ultrasound scan. The d-dimer test is elevated with blood clots but general inflammation and other conditions also lead to elevation. The ultrasound scan can show whether blood is flowing normally through your vein. Your doctor will make a recommendation about which test to do based on how likely it is that you have a DVT. For example, if you have a negative D-dimer test and have a low risk of DVT based on the doctor’s assessment, then an ultrasound isn’t needed.

How is DVT treated?

The main aim of DVT treatment is to prevent the clot from getting any bigger, and prevent it from breaking loose and causing a pulmonary embolism. After that, the goal is to reduce your chances of deep vein thrombosis happening again. Treatment will depend on the location and severity of the clot. Treatment usually includes a combination of medicine and compression.

With treatment, the pain and swelling usually reduces within a few days of starting treatment.

Medicines – anticoagulants

Anticoagulants work by interrupting the clot-forming process. For the treatment of a DVT, anticoagulants can stop the existing clot from getting bigger.

Common examples of anticoagulant medicines are:

  • rivaroxaban tablets
  • enoxaparin (also called Clexane) which is given by injection under the skin (subcutaneously). Some people need to be given this for a few days before they can change to the pills.
  • warfarin tablets. This needs regular blood tests.
  • dabigatran capsules. 

How long you will need anticoagulation treatment depends on many factors but it is usually taken for at least 3 months. In some cases, it may be needed for a longer period or even lifelong.

DVT in pregnancy is treated differently and usually needs a longer treatment course. Your doctor will give you advice on the treatments available.

Watch for signs of bleeding. These medications help to prevent dangerous blood clots from forming or getting bigger but they also can make bleeding more troublesome. It is important to keep yourself away from situations where you might get injured and seek medical care if you have signs of bleeding. 

You may like to consider getting a medic alert tag. If you need treatment but you're too unwell to explain your medical conditions, the tag will inform medical personnel that you are on an anticoagulant and are at risk of bleeding.

Compression stockings

These are special types of stockings called 'graded compression stockings' that are made from special elastic to give support to the lower legs. They encourage circulation and help to reduce swelling. The pressure they provide helps reduce the chances that your blood will pool and clot. These stockings are worn on your legs from your feet to about the level of your knees.

How can DVT be prevented? 

Although DVT cannot be prevented in all situations, there are a few things you can do to lower your risk:

  • Avoid sitting for long periods of time. Elevate (raise) your legs if you are sitting for moderate periods of time. 
  • Do not cross your legs when sitting. 
  • Get up and move around every hour or so.
  • If you are travelling on a long journey or are bedridden in hospital there are special precautions you can take. See travel-related DVT and hospital-related DVT.
  • If you smoke, quit smoking or reduce the amount that you smoke. The nicotine causes your blood vessels to become smaller which means the blood flow is decreased.
  • If you are overweight, aim to reduce weight. 
  • Exercise regularly. 
  • Keep hydrated – drink 6–8 glasses of water (200–250 mLs) a day.
  • Avoid alcohol and medications that make you drowsy because they make it harder for you to move around.

Learn more

Deep vein thrombosis Patient Info, UK
Deep vein thrombosis Southern Cross, NZ
Deep vein thrombosis in pregnancy Healthinfo, NZ


  1. Deep vein thrombosis (blood clots) Centres for Disease Control and Prevention (CDC), US, 2020
  2. DVT (Deep vein thrombosis) NHS, UK, 2019

Reviewed by

Jeremy Steinberg is a GP with special interests in musculoskeletal medicine, evidence-based medicine and use of ultrasound. He's been reviewing topics for Health Navigator since 2017 and in his spare time loves programming. You can see some of the tools he's developed on his website.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Jeremy Steinberg, FRNZCGP Last reviewed: 08 Mar 2022