I want to donate blood, but I’m also curious as to how blood banks take my blood and store it.

You are doing a good deed. There are always people – accident victims, patients undergoing surgical procedure, leukaemia patients and so on – who need blood.

But you should also know that blood banks all around the world follow a certain procedure, as outlined by WHO guidelines. For example, not everyone is allowed to donate blood.

Really? Why is this so?

Imagine that you are a patient receiving someone else’s blood. The last thing you want is to contract an infection from the donated blood. So blood banks use various processes to try to prevent infections transmitted by blood donations.

The first important procedure is to only recruit blood donors from people who are known to have low rates of infection for diseases that are carried by blood.

For example, people who do NOT use intravenous drugs; people who do not have HIV or hepatitis C; people who were not in Britain at a certain time when mad cow disease was rampant; people who have had cancer; and people with bleeding disorders.

There are screening questions that a potential donor has to go through before he is allowed to donate blood. These vary from country to country.

After donation, the blood is tested again for common infections in that area before it is processed for use.

What about children and old people? Can they donate blood?

Actually, the donor criteria is quite strict. For your own health and wellbeing, you must:

• Be aged between 16 and 60 years old. So children below age 16 and people above 60 are not allowed to donate blood in case their bodies cannot take the blood loss.

• You must weigh at least 45kg.

• Your haemoglobin level must be at least 12.5 g/dl. Imagine if you are already anaemic and you donated blood. You will have dizzy spells and keel over!

• You must be in good health. You also must not have any infections, even coughs and colds, in the past week.

• You must not have had a fever in the past three weeks.

Is blood donation painful? I don’t like needles, and I can’t imagine having a needle in my arm for so long.

Actually, the needle is not in your arm for the procedure. The tube is.

The phlebotomist (person who collects blood) selects a large, firm vein in your antecubital fossa.

That is the area of flesh and skin in front of your elbow. This area is preferably free of skin lesions and scars.

Then, the phlebotomist applies a tourniquet to your arm. She will disinfect your skin where the puncture will take place. Your skin is allowed to dry completely, or for at least 30 seconds.

Then she performs the venepuncture. A 16-gauge needle will be used, and this is attached to the blood collection bag. The needle just punctures your skin, and then it is withdrawn with the tube left behind.

During the blood collection, you are asked to open and close your fist slowly every 10 to 12 seconds to keep the blood pumping. Then the phlebotomist will remove the tourniquet once the blood flow is established, or after two minutes – whichever comes first.

The phlebotomist will closely monitor you and the injection site throughout the whole process. She will look for pallor, sweating, and ask you if you feel dizzy.

No, the process is not painful. Not after the initial needle puncture. And remember, you are doing a good deed.

How long does blood donation last?

The procedure itself lasts for eight to 10 minutes, though it may vary from person to person. That is how long it takes to collect a pint of blood.

But the actual process of screening and setting up will take around one hour fifteen minutes.

It’s literally something you can do during lunchtime.

After your blood has been collected, you will be asked to remain sitting in the chair for a few minutes, just in case you stand up too quickly and get dizzy due to orthostatic hypotension – because you have just lost a pint of blood.

The phlebotomist will inspect your puncture site and make sure it is not bleeding. A bandage will be applied.

You will be offered some refreshments.

Are there any side effects from donating blood?

Not for most people. But do look out for the formation of a haematoma (blood collecting in a pool under the puncture site), which occurs in 2% to 3% of donors.

Of course, beware symptoms or signs of too much blood loss, which include dizziness, fainting, low blood pressure, paleness and sweating.

Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health, computers and entertainment. For further information, e-mail starhealth@thestar.com.my. The information contained in this column is for general educational purposes only. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.