Problems with your calves

Having last month encouraged you all to get a post Covid check-up, this month I am going to look at the common problems we see in GP land and in the Emergency Departments in Cork.

I’m going to chat about the dreaded blood clots in the legs, the deep vein thrombosis and its even more dreaded sequel the blood clot on the lung, the pulmonary embolus.

Calf pain is a common problem. How do we decide if it is a blood clot or just a muscular strain.         First, a bit of anatomy. Blood returning from the legs has to beat gravity. The muscles in the calf, the gastrocnemius and soleus, have the ability when they contract to pump the free-flowing blood back up to the heart against gravity. Together they are called the peripheral heart. Valves in the deep veins stop the blood back-flowing and this usually works well.

I have mentioned the deep veins, which you do not see, but if the valves in them start to fail, as they do as we get older or go through pregnancies, the pressure from the deep system now transfers and dilates the superficial veins in the legs, which become prominent as varicose veins. Most of the time these present merely as a cosmetic problem but sometimes contribute to aching legs and ulcers on the lower leg around the ankle, as the tissue becomes less well drained and poorly oxygenated, which all equates to poor healing.

Blood leaks out around the ankle is an irritant and causes itchy, dark blue patches as varicose eczema. If you are in the supermarket and someone drives their trolley into your lower leg, where you have varicose eczema, the skin breaks then an ulcer forms and it can take months to get better. Be careful!

By the way the big superficial vein in your leg is the saphenous vein, running from the inside of your ankle to your groin, where it joins the deep system as the femoral vein. The clever heart surgeons harvest this vein and use it to bypass narrowed arteries in the heart as a Coronary Artery Bypass Graft, CABG. Very handy! We also sometimes use this vein to give fluids in children when the veins in the arm are inaccessible, as it can be located above the ankle with a simple operation.

During Covid we became aware that this infection causes blood to clot more easily and I have seen hundreds of patients concerned about blood clots in their legs or chest.

So how do we determine if the pain in your calf or your swollen ankle is serious? It can be difficult. First, we look at risks. You may know that long haul flights in rare circumstances can cause blood clots but there are many others. Are you on the pill? Have you or a family member who had a clot?Have you active cancer? Have you been laid up in bed for a few days for example? The doc then examines your leg looking for deep pain in the calf, unilateral swelling, a significant measured difference in the girth of the calf, a warmer leg and a leg with dilated veins. A score is given, the so-called Wells score; if you score high, off you go to hospital.

Why the panic? Well, with a clot in the deep muscle of the calf, rather like a log falling into a river, if this is pumped upstream, next stop where the river narrows is the lung and that can be fatal. It blocks the circulation to a lung or even both lungs as an embolus, and blood now cannot take up oxygen from the lungs! A cardiac arrest can occur, as the heart pumps against an immovable blockage at its most dramatic and serious presentation. If the blockage is less complete and the clot smaller, moving to a smaller vessel in the lung before it jams, it can cause a pain on breathing in deeply, that is a pleuritic pain, shortness of breath and coughing up blood.

So, you arrive in hospital, we will repeat the examination and, if pretty sure there is a clot, an ultrasound is done. If we are not quite so sure, then a special blood test is done. This is called a D dimer test: It measures if there is a blood clot anywhere in the circulation. The level increases with age, so we build in a correction factor and, if still raised again, an ultrasound is done.

A blood clot in the calf is not a major problem but if it starts to move up the leg towards the groin then it certainly is. The log is moving on. We call this clot propagation. An ultrasound determines whether the deep veins in your groin compress. It takes minutes, is performed by an expert sonographer and if the vessels compress, as pressure is put on the probe, then all is good. If they do not, you have a blood clot, which can be visualised within the vein sometimes. Even if the ultrasound is negative and the suspicion high, the test can be repeated a few days later.

So why is it that if you have pain in the calf, the calf itself is not examined with ultrasound? Good question! The vessels in the calf are small and many and a complete examination of every one of them could take hours; and bear in mind the clot only becomes a big problem when it extends or propagates above the knee.

Blood clot mimics are many: A torn muscle, a cyst behind the knee (a Bakers Cyst) simple cramp, fluid retention to name but a few. These can often be teased out with a careful history and examination.

If a blood clot is found and there is a powerful reason for having one, say a recent operation and immobility, we call that a provoked clot and blood thinners are prescribed for three months. If there is no reason for a clot forming then blood thinners may be needed for much longer. This is where the blood specialists come in. They look for reasons for unprovoked clots and investigate for inherited or acquired clotting disorders and there are many. They will then make recommendations on the duration of treatment.

I have mentioned ultrasound. We are taught basic ultrasound techniques in the Emergency Department, we are not experts and rely on specialists to confirm or refute our ‘have a go’ findings, it is so important that no chances are taken. I feel a huge level of frustration that I have left it so late in my own career to learn ultrasound.

I confidently predict however that in the future every GP and hospital doctor will learn to use ultrasound. The stethoscope after all has been around with little modification for over 200 years! It was invented by a French doctor, Dr. Rene Laenec, as previously doctors pushed their ears against a patient’s chest to hear what was going on. You can imagine some difficulties and potential embarrassment with the odd mademoiselle! 

Next month I will look at other common problems. I enjoyed working in Bantry Minor Injury Clinic for many years and will cover common minor injuries next month in my ramblings. 

Dr Jeff Featherstone

Dr Jeff Featherstone is a West Cork GP and A&E doctor at Mercy University Hospital and Cork University Hospital.

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