There are two main complications of deep vein thrombosis (DVT): pulmonary embolism and post-thrombotic syndrome.
Pulmonary embolism
This is the most serious complication of DVT. A pulmonary embolism happens when a piece of blood clot (DVT) breaks off and travels through your bloodstream to your lungs, where it blocks one of the blood vessels. This is serious and in severe cases, can be fatal.
If the pulmonary embolism is small, it might not cause any symptoms. If it is medium-sized, it can cause breathing difficulties and chest pain. A large pulmonary embolus can cause the lungs to collapse and result in heart failure.
About one in 10 people with an untreated DVT develops a pulmonary embolism severe enough to cause these severe symptoms or even death.
Post-thrombotic syndrome
If you have had a DVT, you may develop long-term symptoms in your calf, known as post-thrombotic syndrome. This commonly affects people with a history of DVT.
If you have DVT, the blood clot in the vein of your calf can divert the flow of blood to other veins, causing an increase in pressure that can affect the tissues of your calf. Symptoms include:
- calf pain
- swelling
- a rash
- ulcers on the calf (in severe cases)
When a DVT develops in your thigh vein, there is an increased risk of post-thrombotic syndrome occurring. It is also more likely to occur if you are overweight or if you have had more than one DVT in the same leg.
