Why do I need a blood test?
There may be many reasons why you have been asked to have a blood test by your GP or consultant:
- To aid a diagnosis
- To monitor treatment
- To exclude a particular condition
- Prior to a Blood Transfusion
The procedure is called venepuncture or phlebotomy. Thousands of these are performed every day all over the country by trained staff.
The procedure is very quick. Some patients do feel some discomfort and occasionally bruising can occur.
Please let your phlebotomist know if you have any disabilities or anxieties which make having blood taken difficult, or if you required additional assistance or an escort.
A fully trained or supervised member of staff (doctor, nurse or phlebotomist) will place an elasticated tourniquet around your arm, just above the elbow.
A small area of your arm will be cleaned with a swab containing alcohol, left to dry, and then a small needle will be inserted into a vein, usually on the arm although (rarely it may be necessary to select an alternative site.
Blood is drawn into the sample tube(s) and then the needle is removed. It is possible that more than one tube will need to be collected for all tests to be completed. The phlebotomist will then usually place a small amount of cotton wool over the site and apply pressure until any bleeding has stopped. The area is then usually covered with a sticking plaster. Some patients take longer to stop bleeding than others (e.g if on anticoagulants like warfarin). You should stop bleeding prior to leaving the area where your blood has been taken.
Important: please let us know if you are allergic to sticking plasters.
What happens now?
Will it hurt afterwards?
The procedure should not be very painful, and most patients will just feel a small sting as the needle is inserted.
Residual bruising is normal and harmless; it will disperse with time and should not require treatment.
The labelling of the sample/s MUST always be done in your presence. Some samples will be labelled with a sticky label which contains a barcode and all of your details. The person taking the blood should sign and note the time it was taken. Samples for blood transfusion (pink lids) must be handwritten by the person taking your blood. In both instances, they should label the samples whilst in your presence and confirm your full name and date of birth for verification.
After your blood has been collected the phlebotomist must label the tube with your patient details:
- Full name
- Date of birth
- Hospital or NHS number
- Date sample taken
- Time sample taken
- Name of person taking the blood
You have every right, as a patient, to check with the person taking your blood that it has been labelled correctly with your details.
What happens to my sample then?
Your sample is sent to the pathology laboratory to join many other samples having the same tests.
Pathology laboratories process thousands of samples every day so getting your details correct is important.
It is very important that:
- The sample has been correctly labelled with your details
- The right tube has been used to collect your blood sample
Please do not contact the laboratory for your results. These will be reported directly to your GP or consultant who will then be able to discuss these with you.
Please be aware that occasionally tests may need to be repeated or follow-up tests arranged.
© North Bristol NHS Trust. This edition published Dec 2021. Review due Dec 2023. NBT002873