Venesection

What is a venesection?

A venesection, sometimes called therapeutic phlebotomy, is the removal of a set amount of blood from a vein, usually around a pint or half a litre. It's used as a treatment for certain blood conditions, and the procedure is similar to donating blood.

What conditions does a venesection treat?

Venesection is commonly used to treat:

• haemochromatosis, a genetic condition where your body absorbs too much iron, which can build up in organs such as your heart and liver and cause damage; since iron is carried in red blood cells, removing blood regularly is the simplest way to lower your iron levels
• polycythaemia vera, erythrocytosis and other conditions causing high red blood cell counts, which thicken your blood, make it flow more slowly, and increase your risk of a blood clot (thrombosis); removing the extra red blood cells reduces this risk.

What are the benefits of a venesection?

Venesection is a simple, safe and effective way to lower the number of red blood cells in your blood. This can reduce your iron levels or make your blood less thick, bringing both to safer levels.

Are there different types of venesection?

Venesection itself is a single, simple procedure. If you have a history of low blood pressure or have felt faint during a previous venesection, you may also be given extra fluids through a drip in your other arm while your blood is taken.

Your doctor will have recommended venesection as the best treatment for your condition. If you'd like to know more about other possible treatments, you can ask your doctor or specialist nurse, who can talk you through the options.

What happens before a venesection?

Tell your doctor or nurse if you take medication to control your blood pressure, as you may be asked to skip a dose before your first visit. Other than this, no special preparation is needed, though it's a good idea to eat and drink something beforehand.

It's fine to drive and carry on with your normal activities before and after your venesection, though we'd recommend not driving to your very first appointment, as you may feel light-headed or dizzy afterwards. You're welcome to bring someone with you for company if you feel anxious.

Try to avoid alcohol on the day before and the day of your venesection, since it can cause dehydration and increase your risk of bruising or bleeding.

What happens during a venesection?

Venesection usually takes place in a haematology day unit or similar clinic, and the whole visit takes around 30 minutes to an hour, though the procedure itself only takes about 10 to 15 minutes. It generally follows this pattern:

1. You sit or recline in a chair or bed, with your arm supported and a tourniquet (tight strap) placed around it, similar to giving blood.
2. A nurse or trained practitioner inserts a needle into a vein in your arm; this may feel uncomfortable for a moment but shouldn't be painful.
3. Your blood is collected into a bag until the required amount has been removed; a nurse stays with you throughout.
4. If needed, you may be given extra fluids through a drip in your other arm.
5. Once finished, the needle is removed, pressure is applied for a few minutes, and a small dressing is put on.
6. You're offered a drink and asked to rest for a short while so your blood pressure can be checked before you leave.

What does recovery from a venesection look like?

Most people carry on as normal after leaving the clinic, though some feel a little 'washed out' for a day or two afterwards. It's a good idea to rest for a few hours, drink extra fluids for the rest of the day, and avoid strenuous exercise.

Try not to smoke for at least 2 hours afterwards, avoid alcohol, and avoid lifting heavy objects with the arm used for 24 hours. You can return to work once you feel well and aren't light-headed or dizzy, and it's a good idea to let your employer know you've had this treatment.

How often you need venesection varies a great deal between individuals and conditions. You might need it weekly at first if your levels are high, then less often, such as every 6 to 12 weeks, once your condition is under control; some people need this treatment for a short time, others for many years.

What are the risks and complications of a venesection?

You might feel light-headed, dizzy, or notice blurred vision during or shortly after your venesection; tell your nurse straight away if this happens. Resting beforehand and having something to eat and drink can help prevent this.

Bruising at the needle site is common and usually fades within a few days. Occasionally, the site can start bleeding again after you've left; if this happens, apply firm pressure for several minutes, and contact the day unit or your nearest A&E if it doesn't stop.

Regular venesections can sometimes lead to anaemia, where you have less haemoglobin than normal, making you feel tired, faint, or breathless. This is easily treated, usually by making your venesections less frequent. Repeated needle insertions over a long time can also lead to some scarring, though your nurse will try to use different veins to reduce this.