Dr Jason Toniolo

Deep vein thrombosis

Deep vein thrombosis refers to blood clots in the veins, usually forming in the legs.

These blood clots cause two problems

  1. They can dislodge, go to the lungs and cause difficulty breathing, heart failure and death
  2. The clots damage the veins in the leg and prevent blood from returning to the heart. This rarely causes big problems immediately after the clot forms, but years later, the leg can have issues due to a condition called post-thrombotic syndrome (PTS)

Why do veins form clots?

All the time, our blood is in balance. As you read this article, your blood forms clots, and yourking down clots. The balance results in no clot forming.

Three things tip the scale towards forming clots:

  1. Something in the blood that makes you prone to clot forming, such as an inherited condition (a genetic blood clotting disorder), or it can be a medication you are taking, such as the oral contraceptive pill or another acquired clotting disorder, such as a cancer somewhere in the body affecting blood clotting pathways.
  2. Damage to the vessel wall – if you cut open a blood vessel, it will try to form a clot to seal the hole in the vessel wall. Similarly, if there is anatomical compression, with the vein being squashed by a structure (see article on pelvic congestion syndrome and May-Thurner syndrome), the irritation to the vein wall causes the vein to release factors that promote blood clot
  3. Lack of blood flow, also known as stasis – If you are unwell and in bed, not moving your legs for prolonged periods, the speed at which blood flows up your legs decreases. Blood that flows fast doesn’t form clots. Blood that sits still forms a clot more easily. Much like if you cut your vein and blood drops on the floor if you watch that blood for a minute or two, you will see it form a clot. People who are in hospital, who have had orthopaedic surgery, or people who are unwell in bed are at higher risk of forming clot

Symptoms of deep vein thrombosis

Many clots below the knee do not have symptoms and are missed. Clots above the knee and certainly above the groin are larger and more likely to cause symptoms.

The symptoms range from mild to very severe. In order, they are:

  1. Sudden onset of pain in the vein, which has formed a clot, due to the inflammation it causes in the area
  2. Redness and heat at the site of the clot, due again to the inflammation
  3. Swelling of the leg, which may be mild or very large (>50% increase in size compared to the other leg, makes one suspicious of a massive blood clot)
  4. Colour changes to the leg – a purple discolouration, which can be subtle and is caused by the veins being engorged with blood as they can not drain properly
  5. Difficulty walking – Large clots above the groin can result in difficulty walking beyond a certain distance. The leg begins to throb with pain as one tries to walk. Blood goes down the arteries to the muscles to help you move, but the return of blood to the heart is blocked, so the leg aches and throbs with swelling and pressure.

Leg ischaemia – some people develop such harmful clots because not enough blood can get back to the heart, the pressure in the veins of the legs gets so high that the arteries can no longer force blood with oxygen into the leg, and the leg isn’t receiving enough blood. This begins with some nerve sensory changes in the toes, progresses to a lack of movement of the limb and can eventually cause death to the tissue of the toes and foot. This is extremely rare and is a medical emergency.

treatment options

Medical treatment

The treatment recommended depends on where the blood clots are.

When blood clots form in veins below the groin, the management is always blood thinners, and most specialists recommend compression stockings, as there is reasonable quality evidence it reduces the chance of someone developing post-thrombotic syndrome or damage to the veins and scarring years down the track.

Blood clots that occur above the groin (iliofemoral segment) are considered for surgical intervention, depending on a series of factors, such as how old the patient is, what other medical issues they have and how severe their blockage and symptoms are.

A young patient with a large clot in their iliofemoral veins will likely have difficulty walking more than 100 metres immediately after the clot forms, but this generally goes away over the next six weeks as the other veins, which are still draining, get larger to accommodate for the blockages in the more significant, named vessels. The issue arises around two years later when the damage to the veins leads to problems with the skin and can cause chronic leg pain. Eventually, some patients develop venous ulcers (refer to venous ulcer section)

Surgical treatment

The surgeries that are done are minimally invasive keyhole operations. 

There are three approaches to removing deep vein clots from the larger vessels in the limb and pelvis:

1. Medicine is used to dissolve the clot. This is called ‘lytic’

2. The clot can be sucked out with a small vacuum cleaner inserted through a small puncture in the skin

3. Finally, newer technologies have large baskets that are moved up past the clot and then dragged down to collect all the clots and delivered out of the body through a small hole in the made vein. 

Each patient requires a different approach, depending on their anatomy, their age and the clot severity. 

Often, patients will need a stent in their left common iliac vein to improve the flow after the clot Is removed and widen the capacity for blood to flow up the left leg.