CLOTS & THROMBOSIS - Full extract 

Paul Nguyen runs an importing business in town. I met him through mutual friends and we regularly have a meal together. One night he rang me at home and asked whether I could call to see his father, who had been staying with him since a recent prostate operation. 

Mr Nguyen senior explained that his left leg had become very sore over the last couple of days. He was perplexed about it all because he could not recall injuring his leg, and he had been recovering from his operation very well. 

His leg was obviously swollen and it looked reddened and inflamed. It also felt warm compared to the other leg. The swelling extended from just below the knee to the ankle, and his calf was very tender to touch. There was no fever and his chest sounded clear. 

I explained to Mr Nguyen that he probably had a deep venous thrombosis in his leg and that it would be better if he went back to hospital for further tests and treatment. He was readmitted to hospital that evening and was immediately commenced on a heparin drip. The thrombosis was confirmed the following morning with an ultrasound examination. His recovery was otherwise uneventful, and a week later he was discharged from hospital on warfarin tablets. 

The mere mention of the word clot is enough to send some people into a spin. There is that awful worry that clots travel to places like the brain and the lung with fatal results, a worry at least partly justified. 

A clot is simply a collection of coagulated blood. When it occurs inside a blood vessel it is called a thrombosis. Aside from causing local symptoms, pieces of the clot can break off and move further down the vessel. This is called an embolus . From a major vein the embolus can travel up to the right side of the heart and then into the lung. This is the most serious complication of a thrombosis in a vein and is called a pulmonary embolus or clot on the lung.

Thromboses can also occur on the arterial side of the circulation. They may block an important vessel like a coronary artery, causing a heart attack, or a cerebral artery causing a stroke. Bits of a thrombus can flick off or embolize from certain arteries and cause further damage downstream. This may happen in the carotid arteries in the neck; small emboli may dislodge into the cerebral circulation and cause a stroke, or into the retinal arteries and cause loss of vision. Likewise, emboli can travel from a femoral artery and cause a blockage further down the leg. It is not possible anatomically for these arterial emboli to travel back to the heart and lungs. The role of low-dose aspirin in preventing arterial thromboses and emboli has been the subject of much research in recent years. For those at risk, the use of aspirin or a similar medication should certainly be considered. 

On the venous side of the circulation again, clots or thromboses in the veins of the leg are a common cause for concern... 

Deep venous thromboses  occur in the deeper veins of the calf or thigh. Typically, the leg becomes swollen, warm and reddened; it is often quite tender to touch as well. They are more likely to occur after periods of prolonged bedrest, post-operatively or after childbirth. A long air flight or an injury to the legs may also predispose to a deep venous thrombosis. 

Any possibility of a deep venous thrombosis requires prompt investigation and treatment. The risk of a pulmonary embolus is the main concern. Ultrasound examination of the leg will usually give a definite answer and distinguish from other causes of painful swollen legs. Treatment consists of hospitalization and an intravenous heparin drip to prevent further enlargement of the clot. After a few days, the patient is switched over to warfarin tablets to keep the blood thin and reduce the risk of further clotting. 

The patient is usually in hospital for a week or so whilst stabilizing on warfarin. The tablets are usually required for about three months; during this time regular blood tests are required to check the warfarin dosage. Care is required with warfarin. Easy bruising and bleeding can occur and it may interact with other medications. It is important for people like the dentist and other doctors to be made aware if someone is on warfarin. 

Deep venous thromboses do tend to recur. For those at risk and having surgery, low-dose heparin and special calf-stimulating machines during an operation can help to prevent further clots occurring. Sometimes deep venous thromboses are noted to have occurred in several members of one family. Special blood tests can be performed to check whether there is any genetic tendency for clots to occur.

Superficial thromboses  are not quite so worrying. They occur when there is clotting and inflammation in a surface vein, like along part of a varicose vein. It might happen after some minor trauma to the leg or perhaps during pregnancy. Often there is a tender area of redness along a ropey portion of vein. 

Treatment consists of rest and elasticized support stockings. Sometimes aspirin or anti-inflammatory medications are used to settle the discomfort. Special topical creams can also provide relief. Although complications are much less common with superficial venous thromboses, problems may occur when they extend a lengthy portion of vein, for instance near the upper thigh or groin. Superficial thromboses also tend to recur. 

Health Tips: 
*  Avoid prolonged periods of immobility. On air flights or long trips keep wriggling your toes. Stretch your legs and go for a walk wherever possible. 
*  Early mobilization after surgery is a good approach. Amongst other things it helps to prevent post-operative deep venous thrombosis. 
*  If you have had a deep venous thrombosis in the past, mention it to your doctor; there are ways to prevent them recurring.

Dr. Andrew Pattison: Common Consultations
North East Valley Division General Practice, Melbourne, Australia.   Disclaimer
  - Last modified: August 18, 2001