Blood donation

Based on Wikipedia: Blood donation

The Gift That Expires

Here's a problem that sounds like it shouldn't exist: we can transplant hearts, grow organs in laboratories, and edit genes with molecular scissors, but we still cannot manufacture blood. Not a single drop. Every unit of blood used in every hospital, every trauma center, every operating room in the world came from a living human being who chose to give it away.

And most of that blood is about to expire.

Red blood cells last roughly forty-two days in cold storage. Platelets—the tiny cell fragments that help your blood clot—survive only five days. This creates a supply chain unlike any other in medicine. You cannot stockpile blood the way you stockpile bandages or antibiotics. The supply must be constantly replenished, a river that can never stop flowing, fed by millions of individual decisions to roll up a sleeve and sit in a chair for an hour.

How It All Works

When you donate blood, you're participating in a process that splits neatly into two categories, though most donors never think about the distinction.

The first and most common type is whole blood donation. A nurse or phlebotomist—the technical term for someone trained to draw blood—inserts a needle into a vein in your arm. Over the next ten minutes or so, about a pint of blood flows into a sterile bag. That's roughly 475 milliliters, or about one-tenth of your total blood volume. Your body will replace the liquid portion within hours; the red blood cells take a few weeks.

The second type is called apheresis, from a Greek word meaning "to take away." In apheresis donation, your blood flows through a machine that separates out specific components—platelets, plasma, or red cells—and returns the rest to your body. This takes longer, sometimes up to two hours, but it allows donors to give specific components in larger quantities.

Plasma, the straw-colored liquid that makes up about 55% of your blood, carries proteins, hormones, and nutrients throughout your body. When separated and processed, plasma becomes the raw material for dozens of medications. People with hemophilia, immune disorders, and burn injuries depend on plasma-derived products.

Platelets are even more specialized. These aren't cells exactly, but fragments of larger cells, and their sole job is to form clots. Cancer patients undergoing chemotherapy often develop dangerously low platelet counts and need transfusions to prevent uncontrolled bleeding. Because platelets only last five days, maintaining an adequate supply requires a constant stream of donations.

The Brief History of Giving Blood

For most of human history, the idea of transferring blood from one person to another seemed like either magic or madness.

Physicians had attempted blood transfusions since the 1600s, usually with disastrous results. Without understanding blood types—a discovery that wouldn't come until 1901—doctors were essentially gambling. Sometimes the patient improved dramatically. More often, they died in agony as their immune system attacked the incompatible blood cells.

The breakthrough came in 1914, almost simultaneously in two different countries. In March, a Belgian doctor named Albert Hustin performed the first non-direct transfusion, meaning blood was collected and stored before being given to a patient rather than flowing directly from donor to recipient. His solution was heavily diluted, more an experiment than a treatment. Eight months later, Argentine physician Luis Agote demonstrated a more practical approach using less dilution.

Both doctors had discovered the same key ingredient: sodium citrate, a compound that prevents blood from clotting. Without an anticoagulant, drawn blood begins solidifying within minutes, becoming useless. Sodium citrate bought time—enough time to collect, store, and transport blood to where it was needed.

The world's first organized blood donor service emerged in 1921, created by a bureaucrat with no medical training. Percy Lane Oliver was secretary of the British Red Cross in London. When hospitals began requesting volunteer donors, Oliver saw an opportunity for coordination. He recruited volunteers, tested their blood types, and kept records so that when a hospital called with an urgent need, he could dispatch a compatible donor within hours.

By 1925, Oliver's service was supplying blood for nearly 500 patients annually. The model spread to Sheffield, Manchester, and Norwich, then jumped to France, Germany, Austria, Belgium, Australia, and Japan.

The term "blood bank" itself was coined in 1937 by Bernard Fantus, who established one of the first hospital blood banks at Cook County Hospital in Chicago. The banking metaphor was apt: donors made deposits, patients made withdrawals, and the institution maintained careful accounts of what was in storage.

Who Gives Blood, and Why

In wealthy countries, almost all blood donation is voluntary and unpaid. Donors give for various reasons—a sense of civic duty, awareness of medical need, the mild boost of confidence that comes from doing something genuinely helpful, or simple social pressure when a workplace organizes a blood drive.

Some donors start because someone they knew needed blood. A friend's car accident, a relative's surgery, a child's cancer treatment. The connection feels personal, even if the blood they donate goes to a stranger.

In developing countries, the picture looks different. When established blood supplies don't exist, people typically donate only when a family member or friend needs a transfusion. This is called directed donation—blood given for a specific recipient rather than the general supply. It sounds more personal, even loving, but it creates problems we'll get to shortly.

Some places pay donors. The United States allows payment for plasma donations, which is why American plasma fills the global market. Other countries prohibit payment entirely, arguing that it attracts higher-risk donors desperate for cash and creates an ethically troubling marketplace for human tissue.

There's also a peculiar phenomenon around disasters. When tragedy strikes—a mass shooting, a hurricane, a terrorist attack—blood donation centers overflow with eager volunteers. The urge to help is immediate and visceral. Unfortunately, this surge often creates an excess supply that will expire before it can be used, while the chronic shortage returns weeks later when the news has moved on.

The Screening Process

Before you give blood, someone has to make sure it's safe—both for you and for whoever receives it.

The process starts with questions. Lots of questions. Have you traveled outside the country recently? Had a tattoo in the past year? Taken certain medications? The questionnaire is designed to identify risk factors for diseases that can be transmitted through blood: HIV, hepatitis B and C, syphilis, and depending on where you've traveled, malaria and other parasitic infections.

One disease deserves special mention because of how strange its transmission can be. Variant Creutzfeldt-Jakob disease, or vCJD, is the human form of mad cow disease. It's caused not by a virus or bacterium but by a misfolded protein called a prion. There is no test that can detect it in blood. No treatment exists. And the incubation period can span decades.

Because vCJD became concentrated in British cattle during the 1980s and 1990s, many countries defer donors who spent significant time in the United Kingdom during those years. If you lived in Britain for more than a few months during the mad cow era, you may be permanently ineligible to donate blood in Canada, Poland, or the United States. The UK itself, sensibly enough, doesn't impose this restriction on its own citizens—there wouldn't be anyone left to donate.

After the questions come basic physical measurements. Your temperature, pulse, and blood pressure are checked. A small blood sample determines your hemoglobin level—the protein in red blood cells that carries oxygen. If you're anemic, donation could make you dangerously so. This hemoglobin check is the single most common reason donors are turned away.

The American Red Cross requires hemoglobin of at least 12.5 grams per deciliter for women and 13.0 for men. Weight matters too. You need to weigh at least 110 pounds for whole blood donation, more for certain types of apheresis. The logic is straightforward: smaller people have less blood to spare.

The Controversial Restrictions

Some donor restrictions have generated fierce debate.

For decades, most countries maintained blanket bans on blood donation by men who have sex with men, abbreviated MSM in medical literature. The policy originated during the early AIDS crisis when HIV was devastating gay communities and testing methods were crude. A man who had sex with another man even once, even decades ago, could be permanently barred.

The science has evolved considerably since then. Modern HIV tests can detect infection within days. Treatment can reduce viral loads to undetectable levels. And epidemiological data shows that risk correlates with recent sexual behavior, not lifetime history or identity.

Policy has slowly caught up. The UK reduced its lifetime ban to a one-year deferral in 2011, then to three months in 2017. The United States followed a similar trajectory. In 2023, the Food and Drug Administration announced new guidelines focusing on individual risk assessment rather than categorical exclusion. Men in monogamous relationships with other men, or who haven't recently had sex, can now donate. The policy still bars anyone—regardless of sexual orientation—who has had sex with an HIV-positive partner or a new partner who engaged in anal sex.

The debate illustrates a genuine tension in public health. Screening restrictions exist because some infections have a "window period" during which they're present but undetectable. No test is perfect. The question becomes how to balance inclusivity against infinitesimally small additional risks—and who gets to make that calculation.

The Paradox of Family Donation

You might assume that blood from a family member would be safer than blood from a stranger. The opposite is often true.

When a father donates blood for his child's surgery, or a sibling gives platelets to a brother with leukemia, special risks emerge that don't exist with anonymous donation. The first is biological: a potentially fatal condition called graft-versus-host disease.

Normally, graft-versus-host disease occurs after bone marrow transplants. The donated immune cells recognize the recipient's body as foreign and attack it. With blood transfusion, the risk is usually negligible because transfused immune cells are vastly outnumbered by the recipient's own.

Between family members, however, the genetics get complicated. If the donor and recipient share certain immune system markers—specifically, human leukocyte antigens, or HLA proteins—the recipient's immune system may fail to recognize the donated cells as foreign. The transfused cells survive, multiply, and eventually turn on the recipient's tissues. The condition is called transfusion-associated graft-versus-host disease, and it's almost always fatal.

The solution is irradiation. Blood destined for relatives must be exposed to gamma rays that destroy the immune cells' ability to divide while leaving the red blood cells functional. Not every hospital has the equipment to do this.

There's another problem with directed family donation: pressure. When a stranger donates blood, they have nothing to hide from anyone they'll ever see again. When a parent donates for their child, family dynamics take over. Drug use, sexual history, that trip to a malarial country that never seemed worth mentioning—disclosure becomes complicated by shame, by fear, by love itself.

Studies consistently show that directed donations from family members have higher rates of positive tests for bloodborne infections than anonymous donations. Not because families are less healthy, but because they're more willing to lie.

What Happens to Your Blood

After donation, your blood enters a processing pipeline that would seem excessive if the stakes weren't so high.

The World Health Organization recommends four core tests for every unit of donated blood: hepatitis B surface antigen, antibodies to hepatitis C, antibodies to HIV (typically subtypes 1 and 2), and a serological test for syphilis. As of 2006, the WHO reported that 56 out of 124 countries surveyed still weren't performing all these basic tests on every donation. In wealthy countries, additional testing often includes screening for West Nile virus, cytomegalovirus, and other pathogens.

Here's something crucial to understand about these tests: they're designed for screening, not diagnosis. The goal is maximum sensitivity—catching every possible positive, even at the cost of some false alarms. When a test comes back positive, the blood is discarded and the donor is notified, but a positive screening result isn't the same as a diagnosis. Additional, more specific testing determines whether the donor actually has the disease.

False positives happen regularly. False negatives are rare but not impossible, particularly for infections so recent that the immune system hasn't yet produced detectable antibodies. This is why blood donation should never be used as a way to get tested for sexually transmitted diseases. If you're worried you might have HIV, go to a clinic. The anonymous test you'd get through blood donation could come back negative during the window period, and your contaminated blood might make it into the supply.

Blood Types: A Quick Explanation

Your blood type is determined by molecules on the surface of your red blood cells. The ABO system, discovered in 1901, identifies whether you have A-type molecules, B-type molecules, both (AB), or neither (O). The Rh system adds another variable, usually simplified to positive (you have the Rh D antigen) or negative (you don't).

The combination gives eight common blood types: A positive, A negative, B positive, B negative, AB positive, AB negative, O positive, and O negative.

Type O negative is often called the universal donor for red blood cell transfusions. Because O negative blood lacks the A, B, and Rh D antigens, most recipients' immune systems won't attack it. In emergencies, when there's no time to determine a patient's blood type, O negative is what gets grabbed from the refrigerator.

But here's a twist that surprises many people: for plasma and platelet transfusions, the system reverses. Plasma from an O-type donor contains antibodies against both A and B blood types—antibodies that could attack a recipient's cells. AB plasma, lacking these antibodies, can be given to anyone. AB positive is the universal platelet donor; AB positive and AB negative are universal plasma donors.

Beyond ABO and Rh, there are hundreds of other blood group systems, most relevant only in specialized circumstances. Donors are routinely typed only for ABO and Rh D, though blood banks screen for antibodies to less common antigens. Before any transfusion, additional testing called crossmatching confirms compatibility between the specific donor unit and the specific recipient.

The Waiting Periods

How often you can donate depends on what you're giving and where you live.

In the United States, the waiting period between whole blood donations is 56 days—eight weeks. Your body needs time to regenerate the lost red blood cells. Donate too frequently and you risk iron deficiency anemia.

Platelet donation, because it returns your red cells, requires much less recovery time. The United States allows platelet donation every seven days, with a maximum of 24 donations per year. Plasma donation can happen even more frequently—twice within any seven-day period in some jurisdictions.

These limits vary substantially between countries. Some are more conservative, some less. The variation reflects genuine scientific uncertainty about optimal donation frequency, combined with different regulatory philosophies and different levels of demand.

What Donation Feels Like

The experience is remarkably mundane for something so significant.

You sit in a reclining chair. A technician cleans a spot on your inner arm with antiseptic. There's a brief sting as the needle goes in—a larger needle than you'd experience at a routine blood draw, because blood needs to flow quickly enough to prevent clotting. Then you squeeze a small ball or flex your hand periodically to keep blood flowing, answer a few more questions, maybe watch whatever's playing on the television mounted on the wall.

Ten minutes later, it's over. The needle comes out, you hold pressure on the site, someone tapes a bandage over the puncture wound. You're escorted to a refreshment area where cookies and juice await, the sugar helping to prevent lightheadedness.

Some donors feel completely fine. Others experience mild dizziness or fatigue. Bruising at the needle site is common and harmless. Fainting is possible but rare. The single most important thing donors can do is hydrate well beforehand and eat something in the hours before donation.

Donating is, statistically speaking, safe. The serious complications—nerve damage, arterial puncture, severe allergic reactions—are extremely rare. The modest discomfort and time investment are trivial compared to what recipients experience.

The Special Case of Therapeutic Bleeding

There's one scenario where giving blood is a medical treatment for the donor rather than a gift to others.

Hereditary hemochromatosis is a genetic condition causing the body to absorb too much iron from food. Left untreated, iron accumulates in the liver, heart, and pancreas, eventually causing organ damage. The treatment is almost absurdly simple: regular bloodletting, which removes iron from the body along with the red blood cells.

Polycythemia vera is another condition treated this way—the bone marrow produces too many red blood cells, thickening the blood and increasing stroke risk. Again, periodic removal of blood brings cell counts back to normal.

Blood collected from therapeutic phlebotomy can sometimes enter the general supply, particularly from hemochromatosis patients whose blood is otherwise perfectly healthy. Some blood banks accept these donations; others don't, depending on labeling regulations and local policies. The blood itself is fine. The paperwork gets complicated.

Autologous Donation: Giving to Yourself

Before planned surgeries, some patients donate their own blood in the weeks leading up to the procedure. This autologous (meaning "from self") donation ensures compatible blood will be available if needed.

The practice peaked in the 1980s and 1990s, driven partly by fear of HIV-contaminated blood supplies. As testing improved and transmission risks plummeted, autologous donation became less common. It's still offered for patients with rare blood types or for whom finding compatible blood might be difficult.

There's some philosophical awkwardness in calling this a "donation" since you're not donating to anyone. You're making a deposit against your own potential future withdrawal. But the term has stuck, and autologous donation follows many of the same procedures as allogeneic donation—the kind where your blood goes to strangers.

Why Donations Fall Short

Despite the millions who donate every year, blood supplies remain chronically precarious.

The math works against us. Only about 37% of the population is eligible to donate at any given time. Of those eligible, only a small fraction actually do. Regular donors—people who give multiple times per year—account for a disproportionate share of the supply. When something disrupts their habits, shortages follow quickly.

The coronavirus pandemic demonstrated this vividly. Blood drives at schools, workplaces, and community centers were canceled. Regular donors stayed home. Hospitals postponed elective surgeries, temporarily reducing demand, but when procedures resumed, supplies hadn't recovered.

Holiday periods are traditionally difficult. Fewer drives are scheduled, regular donors travel, and the supply dwindles just as icy roads and family gatherings increase the number of accidents.

Certain blood types face particular scarcity. O negative, the universal donor type, is always in high demand and perpetually undersupplied. Certain rare types, more common in specific ethnic populations, become critically scarce when those communities are underrepresented among donors.

The Future of Blood

Scientists have worked for decades to create artificial blood—or, more precisely, artificial oxygen-carrying solutions that could replace red blood cells in emergencies. None have reached widespread clinical use. The biology turns out to be fiendishly complex. Red blood cells don't just carry oxygen; they regulate where it's released through subtle chemical interactions. Synthetic alternatives tend to dump oxygen indiscriminately, causing dangerous side effects.

More promising is the prospect of growing blood cells from stem cells. In late 2022, researchers in Britain announced the first transfusion of lab-grown red blood cells into human recipients. The cells were grown from donated stem cells, cultivated in laboratories, and concentrated for transfusion. The technology remains experimental and expensive, but it points toward a future where blood supplies might be manufactured rather than donated.

For now, though, the system remains stubbornly human. Every bag of blood in every refrigerator started inside someone's circulatory system. The technology is medieval—a needle, a bag, gravity—dressed up with modern testing and tracking.

Finding a Donation Center

If reading this has made you want to donate, the logistics are simple.

In the United States, the American Red Cross operates the largest blood collection network, but many hospitals and regional blood banks also accept donations. Most allow appointments to be scheduled online. Walk-ins are sometimes possible but less reliable, particularly during times of shortage when appointment slots fill quickly.

In the United Kingdom, the NHS Blood and Transplant service coordinates collection. Other countries have their own national services, often connected to Red Cross or Red Crescent organizations.

The whole process—registration, screening, donation, and recovery snacks—takes about an hour. The actual blood draw takes roughly ten minutes. One hour, repeated a few times a year, might save several lives.

That's not hyperbole. A single whole-blood donation, separated into components, can help multiple patients. One pint can become red cells for a trauma victim, platelets for a leukemia patient, and plasma for someone with a clotting disorder.

The gift expires. The need never does.