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What is a venesection?

Venesection (Phlebotomy) is the act of drawing or removing blood from the circulatory system through a cut (incision) or puncture for the purpose of analysis, blood donations or treatment for blood disorders. When performed as part of a patient's treatment for several blood disorders the aim is to decrease iron in the blood or decrease red blood cells.

Haemochromatosis and polycythemia are two disorders which require the treatment of venesection.


Haemochromatosis can be caused by either a genetic disorder or from a variety of factors including alcoholism and is life-long. In this disorder too much iron is absorbed into the body from the diet—over and above the body's needs. Once iron is absorbed into the body there is no way for it to be excreted so, over time, deposits build up in the body tissues: heart, liver, pancreas, pituitary gland and joints, resulting in disease. If untreated, this disease can be fatal. Liver cirrhosis, cancer, arthritis, early menopause, loss of libido, impotence, heart problems such as congestive heart failure, can all be caused by untreated haemochromatosis. Giving blood is the only way to prevent the damage that is done to organs and joints throughout the years. By removing blood volume via venesection the level of iron in the blood is reduced.


Polycythemia is a blood disorder where the body makes too many red blood cells. Thickening of the blood occurs when the number of blood cells rises above the normal levels. This blood thickening increases the chance of blood clots forming. Blood clots can lead to strokes, heart attacks or pulmonary embolisms. Without treatment polycythemia can be life-threatening, however, with proper medical care, many people experience few problems related to this disease. Venesection, in this instance, is used to reduce the number of blood cells by decreasing the blood volume. Treatment is continued until the haematocrit reaches a normal level. How often venesection is performed depends on the severity of the disease.

On your admission

Before the venesection is carried out your nurse will explain the procedure to you and ask you a few questions regarding your medical history. Some patients experience a fainting episode during this procedure. Please notify your nurse if you have ever experienced fainting when giving blood or having blood tests.

Your blood pressure and other observations will be taken before the procedure is performed. A needle is used to insert a cannula into your vein. The cannula is secured into position with tape. A bag is connected to the cannula for the purpose of collecting the blood. Bloodletting (withdrawing of blood) is not a painful process. The pain that may be felt during this procedure is when the needle initially punctures the site but that does subside.

It generally takes approximately 15 minutes to drain 450 mls of blood. Sometimes, depending on your requirements, your doctor may order fluids to be given via another cannula inserted into your opposite arm. These fluids will be given over one to two hours. During your procedure you will be given refreshments to help prevent dehydration.

After your procedure

Following your procedure your blood pressure and observations will be checked. When your blood pressure is stable you will be able to be discharged. Prior to you leaving, your nurse will remove the cannula/s and cover your puncture site/s. It is advised that you observe your venesection site for bleeding and signs of infection.

What to expect

  • The procedure is safe and without side effects (in most cases).
  • Immediately after the procedure you may feel dizzy. This can be minimised by resting and drinking fluids.
  • You may feel a little lethargic for a couple of days.
  • You can resume all your normal activities after the procedure.
  • Keep hydrated and drink two litres of fluid daily for 48 to 72 hours following your procedure.
  • The frequency of the venesection treatments is different for everyone and is performed according to one's condition. At first you may require up to weekly venesections. When your blood levels are under control you may only require the venesection every six to twelve weeks.

What to avoid

After your procedure it is important for you to avoid:

  • drinking alcohol for 72 hours
  • strenuous exercise and heavy lifting for 24 hours.

Please contact Mater Hospital Brisbane Procedure Unit on 07 3163 8324, Mater Hospital Brisbane Emergency Department on 07 3163 8111 oryour general practitioner (GP) if any of the following occur after discharge:

  • bleeding
  • fever
  • redness at venesection site
  • smelly discharge from your venesection site
  • you feel insignificantly unwell in any way.

Mater Hospital Brisbane

Raymond Terrace, South Brisbane Q 4101

Telephone 07 3163 8111


Staff of Mater Hospital Brisbane, Raymond Terrace, South Brisbane, Q 4101

© 2011 Mater Misericordiae Ltd. ACN 096 708 922.

Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: PI-CLN-420044
Last modified 17/3/2020.
Consumers were consulted in the development of this patient information.
Last consumer engagement date: 11/8/2015
For further translated health information, you can visit healthtranslations.vic.gov.au/ supported by the Victorian Department of Health and Human Services that offers a range of patient information in multiple languages.
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