DVT – what is it?
Deep vein thrombosis (DVT) is a condition in which a blood clot (thrombus) forms in a vein. This is commonly in the deep veins of the legs or pelvis. This thrombus can dislodge and travel in your blood to different parts of your body. Often, this clot can reach the vascular system of your lungs – particularly to the arteries of the lungs. It can lodge here and it can essentially cause a blockage to this pulmonary vascular system and lead to something called a pulmonary embolism, which can be life-threatening.
Does everyone get DVTs?
The risk of developing blood clots is generally quite small. There are certain risk factors that can increase your risk of developing blood clots:
i. Persons aged 40 years or over
iii. Underlying medical conditions that increase the risk of venous thrombosis (e.g. inflammatory bowel disease, systemic lupus erythematosus (SLE))
iv. Active cancer or recent treatment for cancer
v. History of having blood clots or family members who have had blood clots
vi. Medications, such as oestrogen-containing medicines (contraceptives and/or hormone replacement therapy)
vii. Recent surgery within the last 3 months, including caesarian section
viii. Hospitalisation with limited mobility, or, ‘bed rest’ for 3 days or longer
ix. Any recent injury, which causes immobility of leg (e.g. leg casts)
x. Pregnancy or the postpartum period (6 – 12 weeks after childbirth)
Some individuals may not have any of the above risk factors and they can still develop DVTs. This is often termed as an ‘unprovoked DVT’.
What does travel have to do with it?
The first ever recorded air travel related DVT was in 1954. The impact of DVTs with air travel is still significant. Any kind of long-haul journey, i.e. travel of more than four hours’ duration increases the risk of DVTs. This may be one single long-haul journey, or even with multiple flights within a short period of time. DVTs can develop within 2 – 4 weeks of a flight, with the risk being highest within the first 2 weeks of a long haul flight.
There are multiple reasons behind this – immobilisation of the lower limbs in cramped seating, dehydration, low atmospheric pressure. These risks are often amplified with our own personal risk factors, such as those mentioned above.
What are the symptoms?
Typical symptoms you may experience are throbbing pain, especially one that comes on while walking or weight-bearing. You may also notice swelling and/or redness in the affected limb.
Some individuals may also experience chest pain, breathing difficulties, coughing up blood, dizziness and/or fainting if the blood clot has travelled up to your lungs.
How is it diagnosed? What tests do I need?
Your doctor will perform a thorough assessment by understanding your condition and concerns and physical examination.
Sometimes, a blood test or an ultrasound of the limb is performed if the diagnosis is questionable. Most of the time, an ultrasound of the affected limb is arranged as soon as possible.
If you are experiencing ‘chest’ symptoms, your doctor may also arrange a CT (computed tomography) scan of your chest to understand the degree of the condition.
DVT Treatment and Prevention
It is important to have a thorough discussion with your family doctor to evaluate your personal risk for developing DVTs, especially with an upcoming long-haul journey.
Simple measures that you can take during flights are:
i. Keep moving and be active
ii. Stay well hydrated and avoid alcohol before and during your journey
iii. Avoid crossing your legs
iv. Avoid wearing tight clothes that may restrict blood flow
In the event you do develop a DVT, the key thing to avoid is any delay for treatment for individuals suspected of DVTs. Usually, a blood thinner is prescribed to treat DVTs. Your doctor will discuss the type and duration of therapy for your condition depending on your risk factors.
Further investigations may be carried out by your doctor to understand whether there are any other conditions that may have led to a DVT.
COVID-19, Travel and Blood Clots
A current or recent COVID-19 infection puts you at a higher risk of developing blood clots. This may be the case even if you were asymptomatic or had mild symptoms. If you will be travelling long-haul within a few weeks of COVID-19 infection, please discuss this further with your family doctor.