Having a venesection

This leaflet explains what a venesection is, and the risks and benefits of having this procedure. It also tells you what to expect when you come in to have this treatment.

When the number of red blood cells in your blood is increased, the blood flow around your body can become slow. This can increase the risk of developing problems like a blood clot. Taking away some of the red blood cells reduces this risk.

In haemochromatosis, iron levels in the body slowly build up, and can damage parts of the body if left untreated. It can be treated by removing some of your blood.

A venesection is the quickest and simplest way of reducing the number of red cells in your blood. It will remove about one pint, or half a litre of blood at a time. The procedure is similar to the procedure for donating blood.

If you are on blood pressure tablets, please do not take them on the day of your treatment.

You do not need to do any special preparation before this treatment and you do not need to bring anything with you. You will be able to drive to and from the hospital and continue with normal activities afterwards. You are welcome to bring someone with you to keep you company during the procedure.

If you come in at the main hospital entrance, please ask at the reception desk for directions. Or go to level 9 of the Sussex Kidney Unit and follow signs for Haematology Services.

Before the venesection is carried out the procedure will be explained to you by a health care assistant or nurse. You can ask them any questions you may have, and they will be happy to answer them. You will be offered a drink before the treatment starts. You will be seated, and a tourniquet is applied to your arm in the same way as if you were having a blood sample taken. The needle, which is already attached to the blood collection bag, is inserted into a vein in your arm. It is fixed in place with tape.

The collection takes about 15 minutes. When it is finished, the needle is removed and pressure is applied to that area for a few minutes. A small dressing is put on. You can have another drink if you want, and you can stay seated for another 20 minutes if you feel you need to. If you are on blood thinners like Warfarin, pressure will be applied for at least 10 minutes and we may ask you to stay a little longer to check there is no bleeding once pressure has been removed.

When the needle is inserted into your arm, it may be uncomfortable for a few seconds. When the needle is removed, it may bleed a little. Just after your blood has been removed, you may feel a little dizzy. This is not unusual and it can help if you rest before you leave the department, and have something to drink. It is a good idea to rest for a few hours after the procedure.

There may also be some bruising on your arm where the needle went in, and this may take some days to go. As with any bruise, it may feel uncomfortable.