Type to Save a Life: Blood Donation

Blood transfusion is an essential part of modern medicine. It is used in surgery, childbirth, and emergency cases, as well as being a component of long term treatment. Without people giving blood, this wouldn’t be possible. 

The first case of blood donation between humans was in 1818, long before blood groups were understood. Nowadays there are strict rules about who can and can’t give blood, as well as tests to ensure that donations are safe for donor and patient.

Janet is a nurse - it’s her job to ensure that donors are able to give blood. First time donors, or donors who’ve had a medical issue with giving blood are given extra tests to ensure their suitability.

A form provides questions for Gillian to answer about recent tattoos, piercings, travel history and medical issues. This prevents diseases she might have picked up since her last donation being passed to a vulnerable patient.

Janet takes a drop of blood from Gillian’s finger to check levels of haemoglobin (a protein that carries the oxygen in red blood cells) in a small sample taken from the finger. Low iron could account for low haemoglobin levels.

Gillian has passed her haemoglobin test and answered all of the questions on the form. She is suitable to give blood and is prepped for donation. Once the needle is inserted, it takes between 5-15 minutes to donate a unit (470ml) of blood. 

The bag is also rocked gently by an automated cradle. Samples of blood are taken during this time for further testing.

Before inserting the needle, the area on Gillian’s arm is cleaned with antiseptic. This prevents any infectious bacteria which might have been on her skin making their way into her bloodstream.

Gillian squeezes an object in her hand and has a cuff wrapped around her upper arm. This forces blood to pump through the vein, making it easier to insert the needle - as well as speeding up the donation.

Many donors are needed to supply the blood bank with enough of each blood type. Platelets - part of the blood that helps it to clot - are also collected here. Donating platelets can take much longer - about an hour and half.

After donating, Gillian is given a cup of tea and a biscuit. She is now free to leave, but it is important to refuel after donating. Donors are advised to rehydrate and relax for 15 minutes - giving blood can use up a lot of energy. 

Once Gillian is ready to leave she can book her next appointment to give blood. She must wait 12 weeks before donating again.

When the needle is removed, a small plaster is applied to the arm. Donors are also advised to add pressure to the area, this prevents any bleeding. The whole process - including tea and biscuit - has taken less than an hour.

As well as replacing lost fluids, sugar can prevent donors from feeling faint after donation. Donors are advised to avoid strenuous exercise the day of donation for the same reason.

Patrick has also given blood today. He feels that it is very little effort and such a great reward for people who need it most. His blood type is quite rare so he makes sure to donate regularly.

Once the blood has been donated, it is sent to a laboratory. Here, a dedicated team of Biomedical Scientists ensure that the blood is safe, organised and can be sent to hospitals. This means that the blood needs to be split into its component parts. 

Blood is made up of three distinct components: plasma, red blood cells and buffy coat. When the blood bags are spun quickly in a centrifuge, the heaviest elements sink the bottom, separating these parts.

The bags contain a full unit of blood. Once the components are separated, they can be split between several bags in smaller amounts for babies and children. One adult donation can provide 4 doses of red blood cells for a premature baby. 

The light top layer is plasma and the lower layer is red blood cells. In between is a layer of buffy coat, rich in platelets - this constitutes less than 1% of the entire sample. 

The scientists working in this lab must work quickly and efficiently so that blood can be delivered to patients in need as soon as possible. This lab in Scotland can process over 800 donations a day.

When blood is taken from a donor, extra samples are also taken. This means that while blood is being processed it is also tested for blood group, diseases and antigens. In this lab, scientists test for specific antigens present on the red cells. 

Antigens are proteins in the blood which provoke the immune system to fight them, so they can be harmful. Patients with antibodies need blood that does not contain certain antigens.  Antibodies are the body's defence system against antigens.

Each of these tubes contains a sample of blood to be tested. Sometimes a patient has a very specific antibody, so they need to be matched with the right donor. Many of these donors don’t even know how rare their blood is.

This blood laboratory often uses highly sensitive machines in order to test many samples at once. However, even highly skilled Biomedical Scientists will sometimes manually complete tests that are very specific. 

This centrifuge is a miniature version of the one used to separate the different blood components immediately after donation. This one is used to separate the same material in test tubes. 

More blood is being delivered to the lab from the donor centre. Blood that has been processed can now be sent on to local hospitals, continuing the cycle. These labs operate 365 days a year to ensure that the supply is always available to those in need. 

Hospitals will communicate with the laboratory to let them know what blood they need. Sometimes, in an emergency, extra blood must be transported quickly. 

When it is being sent to hospitals blood must be delivered in special conditions to ensure that is will be safe to use upon arrival. Plasma is frozen, and so must be kept very cold with the help of dry ice during transportation. 

Staff must process and deliver blood as quickly as possible, as some products have a limited shelf life. Red blood cells can be kept for 35 days but platelets can only be kept for 7 days.

To ensure component and staff safety, there are strict rules in the laboratory. Scientists must wear white coats, and unauthorised access is forbidden. Isolating samples is a key component of scientific testing to ensure that the results are accurate.