The U.S. is running low on its most critical blood type — and hospitals keep wasting it

American Society of Anesthesiologists (ASA) / Anesthesiology Open

Imagine a trauma bay at 2 a.m. A patient arrives unconscious, bleeding heavily, blood type unknown. The team reaches for O-negative blood — the one type that can be given to anyone without risking a deadly immune reaction. It is, in the most literal sense, the blood that keeps strangers alive.

Now imagine the cooler is empty.

That scenario is no longer hypothetical. Blood banks across the United States are reporting dangerously low O-negative supplies, and the problem is not just about donation shortfalls. It is about how hospitals use — and overuse — the scarcest resource in transfusion medicine. A new article published in Anesthesiology Open, an official journal of the American Society of Anesthesiologists (ASA), argues that the medical profession itself bears part of the blame, and that anesthesiologists are uniquely positioned to fix it.

Eight percent and falling behind

O-negative red blood cells lack the A, B, and Rh-D antigens that trigger immune reactions in recipients with different blood types. That absence makes O-negative universally compatible — and universally demanded. But only about 8% of White/Caucasian individuals carry the type, with even lower rates among other racial and ethnic groups. Supply has never come close to matching the outsized role O-negative plays in emergency rooms, operating theaters, and trauma centers.

The current moment is especially precarious. The American Red Cross reports that severe winter weather and cancelled blood drives have created one of the most significant donation shortages in recent years. Through March 2026, the Red Cross is offering a $15 Amazon gift card to each donor in an effort to rebuild stocks — a measure that signals just how thin the margins have become.

"O-negative blood is critical when patients need immediate transfusions before their blood type can be confirmed, such as during trauma care or other life-threatening emergencies," said lead author Brent R. Lee, M.D., MPH, FASA, of North American Partners in Anesthesia. The stakes extend beyond individual patients: a mass casualty event could drain an already depleted O-negative supply entirely, leaving hospitals unable to treat the people who need it most.

The anesthesiologist's outsized role

Here is a number that surprises most people outside medicine: anesthesiologists administer up to 60% of all blood transfusions in the United States. They are the clinicians managing blood loss during surgery, guiding resuscitation during trauma, and making real-time decisions about which units to hang on an IV pole. That volume of influence means their habits — good or bad — ripple across the entire blood supply.

The problem, as Lee and his colleagues describe it, is partly one of inertia. When a patient's blood type is unknown, reaching for O-negative feels like the safest default. And for certain patients, it genuinely is. But for many others, O-positive blood works just as well, and it is far more plentiful.

The distinction matters most for one specific population: women of childbearing potential. Giving Rh-D-positive blood to an Rh-D-negative woman can cause her immune system to produce antibodies against the Rh-D protein. In a future pregnancy, those antibodies can cross the placenta and attack a fetus's red blood cells — a condition called hemolytic disease of the newborn. For this group, O-negative remains the only safe emergency option.

But for men, and for women beyond reproductive age — typically those 50 and older — O-positive blood carries no such risk. The article argues that switching these patients to O-positive as a default emergency blood type could dramatically reduce the drain on O-negative reserves without compromising safety.

Start smart, switch sooner

Lee and his co-authors endorse the American Red Cross's "Empower Group O Care" initiative, which boils its guidance down to a simple mantra: start smart and switch sooner. The practical recommendations are straightforward:

• Begin emergency transfusions with O-positive blood for male patients and female patients beyond childbearing potential when blood type is unknown.
• Perform blood typing and crossmatching as early as possible to minimize total O-negative use.
• Stop giving O-negative units after the patient's actual blood type has been determined — a step that sounds obvious but is skipped more often than hospitals like to admit.
• Coordinate with blood bank staff and other hospital teams to prioritize the switch to type-specific blood once results are available.

Beyond smarter blood-type selection, the authors point to established blood-conservation techniques that can reduce the total number of units a patient needs. Cell salvage — collecting and reinfusing a patient's own blood lost during surgery — is one. Point-of-care viscoelastic testing, which gives clinicians a rapid snapshot of how well a patient's blood is clotting, helps avoid unnecessary transfusions driven by guesswork. And pharmacologic agents like tranexamic acid, which stabilizes blood clots, can reduce bleeding in high-risk surgical and trauma scenarios.

Why the old habits persist

If the solutions sound simple, it is worth asking why hospitals have not adopted them universally. Part of the answer is risk aversion. In a high-pressure environment where a wrong blood type can kill, defaulting to the safest possible option — O-negative for everyone — feels prudent. Changing that reflex requires not just new protocols but a cultural shift, one where clinicians trust that O-positive is genuinely safe for the patients who can receive it.

There is also a systems problem. Blood typing and crossmatching take time, and in a chaotic trauma resuscitation, ordering those tests early can fall off the checklist. The "switch sooner" part of the Red Cross initiative depends on labs returning results quickly and on clinical teams acting on them immediately — neither of which is guaranteed in every hospital.

Still, the cost of inaction is concrete. Every O-negative unit used for a patient who could have safely received O-positive is a unit unavailable for the next pregnant woman who arrives in hemorrhagic shock, or the next child whose blood type has not yet been determined. The arithmetic is unforgiving.

A call that extends beyond the OR

The article is not only directed at clinicians. Lee and his colleagues stress the need for greater public awareness about blood donation, particularly among people with O-negative and O-positive blood. The chronic shortfall is not a problem that hospital protocols alone can solve — it requires more donors walking through the door.

That message carries extra weight right now. The convergence of winter weather disruptions, declining donation rates, and a healthcare system still managing the long tail of pandemic-era staffing challenges has created a supply environment with almost no buffer. Blood banks typically aim to maintain a several-day reserve of each blood type, but O-negative inventories at many centers have dropped to a single day or less. The next large-scale emergency — a natural disaster, a mass shooting, a multi-vehicle pileup — would test a system already running on fumes.

The dual approach matters. Hospital-side conservation buys time, but it cannot manufacture red blood cells. Only donors can do that. And the donors most needed — those with O-negative and O-positive blood — are often unaware of how disproportionately their contributions matter to emergency medicine. Public health campaigns have historically focused on total donation volume rather than targeted recruitment by blood type, a gap the Red Cross initiative is now trying to close.

"It is imperative that we maximize the benefits of blood transfusion, while strengthening the security of the nation's blood supply," Lee said. The statement is measured, as medical journal language tends to be. But the underlying message is urgent: the way American hospitals use O-negative blood is unsustainable, and the window to change course is not infinite.