Skip to content
06 April 2022

What's so good about high spec blood?


All donations are special, but some donations are extra special because they support the most vulnerable patients in need.

As an O negative donor, you may be aware that your blood type is special. However, in addition to being only 7% of the donor population, some are even more unique... it could be you, and you might not even know about it.

If you receive a call or a text from us asking you donate on a specific day, this could be because are also part of an extra special group known as a O negative high specification donors (also called 'high spec').

As a high spec donor, your blood is very rare, very special, and very much in demand because it's the least likely to give a patient a reaction if transfused. High spec blood is used for the most at risk patients, including babies, patients undergoing chemotherapy, and those with immunodeficiency conditions.

It is vital that we have always have adequate stocks of high spec blood available to patients in hospital when it's required. If you are O negative, and haven't given for a while, please come back and donate soon. The more O negative donors we have available, the easier it is to ensure that this extra special gift is ready and waiting for those in need.

What is 'high spec' blood?

If we have ever got in touch with you to tell you your O negative (O neg) blood is also Kell negative (Kell neg), CMV negative (CMV neg) and 'rr', this means your blood is very rare, very special, and very much in demand, because it's the least likely to have a bad reaction if transfused. It can give the most defenceless patients in Scotland the very best chance of survival.

Interested in finding out more about types of high spec blood? Our festive story gives you all the information in an easy to understand Christmas themed way. 

What is the urgency if I get the call?

Blood is at its best when it's freshest.  Usually, it's fine to use blood for up to 35 days after donation (although the nutrient value does deplete over time). However, for babies and newborns needing transfusions (or even intra-uterine transfusions), the blood needs to be less than five days old.

  • Book your appointment online, or call us on 0345 90 90 999 (Mon-Fri, 9am-5pm)

Current blood stock levels across Scotland Tuesday 27 February

We aim to retain 6 days of stocks at any time in order to meet the requirements of patients in Scotland.

Learn more about blood types