Scotland's blood service has issued its first ever amber alert after stocks fell to critically low levels, with hospitals told to use Type O blood only when essential.

The Scottish National Blood Transfusion Service (SNBTS) said blood stocks had dropped to unprecedented low levels because of a shortage of donors and increased use of Group O blood over recent months. The alert came into force at 9am on Tuesday 10 November and will run for an initial four to six weeks, kept under close review.

Group O stocks below two days' supply

Group O blood has fallen below two days' supply on several occasions recently, SNBTS said, against a target of holding five to seven days' supply of all blood groups. Hospitals have been asked to put emergency measures in place to minimise use, move staff to laboratories to vet all use of O type blood, and make greater use of alternatives to transfusion where possible.

Urgent, emergency and trauma surgery, cancer surgery, transplant surgery and transfusions for people with long-term conditions will continue as normal.

Donor numbers down by almost 30,000 in a decade

The service said donor numbers had fallen by 24 per cent over the past ten years, a drop of just under 30,000 donors, and that only around 2 per cent of the eligible population now gives blood. About 3,385 donor appointments need to be filled each week, but only 85 per cent are filled on average. Hospitals in Scotland need 135,000 units of blood each year.

Dr Lorna McLintock, medical director at SNBTS, said: "To supply hospitals with the 135,000 units of blood they need each year to treat patients, appointments need to be fully booked all year round."

Donors, particularly those who are O negative or O positive, are asked to book appointments at donor centres in Aberdeen, Dundee, Edinburgh, Glasgow and Inverness. Appointments can be booked at scotblood.co.uk or by calling 0345 90 90 999.