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What Causes Swollen Ankles?

The commonest cause of swollen ankles and feet is a problem with the valves of the leg veins. This condition is called ‘Chronic Venous Insufficiency’ and the swelling is referred to as ‘Venous Oedema’.

Chronic Venous Insufficiency accounts for 90% of cases of fluid retention around the ankle. Chronic Venous Insufficiency is diagnosed by a Duplex Ultrasound Scan.

This patient was completely unaware that she had swollen ankles until I pointed out the indentations left when she removed her socks.

Pitting or dents caused by pressure is the strongest suggestion that there is fluid retention or oedema.

Mild cases may not need intervention other than gentle exercise, elevation and compression socks. However, over time, chronic oedema will interfere with the exchange of nutrients and oxygen to the skin. This may make the leg vulnerable to injury and infection.

Should I Be Worried About Venous Ankle Swelling?

How Severe is Venous Oedema?

An international panel of experts has produced a severity scale for leg vein problems called CEAP.

As you can see in the diagram, the scale goes from C1 (leg spider veins and blue veins) to C6 (an open leg ulcer). Ankle swelling due to vein disease is half-way along the severity scale.

Without treatment, leg veins get worse. Varicose veins initially may cause no symptoms but eventually the ankle begins to swell. The swelling is absent in the morning and gradually gets worse during the day. By the end of the evening, the swelling is apparent as an indentation left by the tops of the socks. 

The presence of high back pressure in the capillaries caused by the Venous Oedema damages the microcirculation leading to Varicose Eczema and then Leg Ulceration in some individuals.

Varicose Eczema and Venous Oedema should be treated at an early stage to prevent Leg Ulcers.

What is the Treatment for Venous Oedema?

Treatment of Venous Oedema should be based on a Duplex Ultrasound Scan. Deep veins problems are usually managed by elevation, massage, skin moisturisers and compression socks. Superficial Vein Problems are usually treated by Endovenous Laser Ablation.

Other Causes of Ankle Swelling

The list of causes of ankle swelling is long:

  1. Injury
  2. Cellulitis
  3. Side effects of medications
  4. Blood clots
  5. Pregnancy
  6. Preeclampsia
  7. Lymphoedema
  8. Heart Failure
  9. Kidney disease
  10. Liver Disease
  11. Underactive thyroid
  12. Insect bite or sting
  13. Being overweight
  14. Eating too much salty food

When Should I See a Doctor with Swollen Ankles?

Mild cases that get better on their own in a few days, do not need anything done.

Chronic venous insufficiency causes chronic persitent ankle swelling and needs referral to a vascular surgeon or vein specialist.

Other reasons to see a doctor are:

  1. The swelling has not improved in a few days
  2. It gets worse


  1. Only one foot, ankle or leg is swollen and there is no obvious cause such as an injury or insect bite
  2. The swelling is severe, painful or came on suddenly
  3. The area is red or feels hot
  4. You have a temperature, feel hot and shivery
  5. You have diabetes
  6. You have a problem with your immune system
For more information visit the NHS Website