Blood facts

Why blood is needed, what happens to it, and how little it costs you to give some.

Why India needs blood

• India needs roughly 4 crore units of blood each year. Collections fall well short of that, and the gap is met by families scrambling for replacement donors at the worst possible moment.
• Someone in India needs blood roughly every two seconds.
• About 1 in 10 people admitted to hospital will need blood.
• A large share of the adult population is medically eligible to donate. Only a tiny fraction ever does — the shortage is one of volunteers, not of eligible people.
• Blood cannot be manufactured. Every unit transfused came out of a person’s arm.
• Demand spikes around festivals and holidays, exactly when regular donors travel and collections fall.

What happens to your donation

• One unit is separated into red cells, plasma and platelets, so a single donation can help up to three different patients.
• Red cells carry oxygen. Platelets stop bleeding. Plasma carries proteins, salts and clotting factors.
• Donating a specific component and returning the rest to you is called apheresis.
• In well-equipped blood banks, the large majority of collected blood is separated into components rather than transfused whole — most patients need one part, not all of it.
• Every unit is screened for HIV, hepatitis B, hepatitis C, syphilis and malaria before it can be issued.

How long blood keeps

• Red cells: around 42 days refrigerated. Whole blood in CPDA solution keeps about 35 days at 2–4°C.
• Platelets: only 5 days, at 22–24°C under constant agitation. This is why platelet appeals are so urgent.
• Fresh frozen plasma: up to a year at −30°C or below.
• Because platelets expire in days, a platelet donor is often needed today, not in general.

Your body afterwards

• An average adult carries about 5 to 6 litres of blood. A donation takes roughly 350–450 ml — under a tenth of it.
• Blood is about 7% of body weight.
• Plasma volume is replaced within 24 to 48 hours.
• Red cells take a few weeks to rebuild, which is why the interval between whole blood donations is 90 days.
• Red cells live about 120 days in circulation. Your marrow replaces them constantly, donation or not.

Blood groups

• There are four ABO groups — A, B, AB and O — each either Rh positive or Rh negative, giving eight common types.
• O negative red cells can be given to a patient of any group, which is why they are used in emergencies before a patient’s type is known. They are always in short supply.
• AB positive plasma can be given to patients of any group.
• O negative is rare in India — only around 7% of people have it.
• In everyday practice a patient receives their own group. Universal donor blood is an emergency measure, not routine.
• Karl Landsteiner identified the first human blood groups in 1901. His birthday, 14 June, is World Blood Donor Day. India marks National Blood Donation Day on 1 October.

How common is each blood type?

Approximate, and varies by region.

What blood actually gets used for