O-negative blood is running out — and hospitals keep using it on patients who don't need it

American Society of Anesthesiologists / Anesthesiology Open

Only about 8% of White Americans carry O-negative blood. Among other racial and ethnic groups, the rate is even lower. Yet this single blood type shoulders a disproportionate burden in emergency medicine: it is the default transfusion choice whenever a patient arrives bleeding and their blood type is unknown. The result is a chronic national shortage that winter weather and cancelled blood drives have pushed to dangerous levels.

A new article in Anesthesiology Open, a journal of the American Society of Anesthesiologists, argues that the shortage is partly self-inflicted. Hospitals continue giving O-negative blood to patients who could safely receive O-positive — a far more available alternative. The authors, led by Brent R. Lee, MD, of North American Partners in Anesthesia, say anesthesiologists are uniquely positioned to fix this, since they administer up to 60% of all blood transfusions in the United States.

The 8% problem

O-negative blood lacks the surface antigens that trigger immune reactions in recipients with other blood types. That makes it safe for anyone in an emergency — the true universal donor. But "safe for anyone" has created a habit: reaching for O-negative blood even in situations where a less scarce type would work just as well.

The core medical reason for restricting O-negative use to certain patients involves the Rhesus factor D (RhD), the protein on red blood cells that determines whether a blood type is positive or negative. Giving RhD-positive blood to an RhD-negative woman of childbearing age can trigger antibody production that endangers future pregnancies. For these patients, O-negative blood is genuinely necessary when the blood type is unknown.

For everyone else — men of any age, and women past reproductive potential — O-positive blood carries no such risk. It is also substantially more common and less likely to be in short supply.

Start smart, switch sooner

The article endorses the American Red Cross's "Empower Group O Care" initiative, built around two principles: start emergency transfusions with O-positive blood for eligible patients, and switch to type-specific blood as soon as the patient's blood type is confirmed.

The specific recommendations are practical:

• Use O-positive blood for all male patients and for female patients over 50 (or otherwise beyond childbearing potential) when blood type is unknown.
• Perform blood typing and crossmatching as early as possible during emergency care to minimize any use of universal donor blood.
• Stop continuing O-negative transfusions after a patient's type has been determined — a practice the authors identify as a significant source of waste.
• Implement cell salvage, point-of-care viscoelastic testing, and pharmacologic agents like tranexamic acid to reduce overall blood use in high-risk bleeding cases.

Mass casualty scenarios and the empty bank

The stakes extend beyond routine shortages. In a mass casualty event — a building collapse, a mass shooting, a multi-vehicle accident — hospitals may need to transfuse dozens of patients simultaneously, most with unknown blood types. If the O-negative supply is already depleted from routine overuse, the consequences could be severe. Lee and his colleagues describe this as a patient safety issue, not merely a supply chain problem.

The American Red Cross has reported that 2026 has seen one of the more significant blood donation shortages in recent years. Severe winter weather disrupted donation drives across the country. Through March, the Red Cross is actively encouraging donations, particularly from O-negative and O-positive donors.

A behavioral problem with a behavioral solution

The irony of the O-negative shortage is that the solution does not require new technology, new drugs, or new regulations. It requires changing a habit. Emergency departments and operating rooms have defaulted to O-negative blood partly because it is simpler — one type fits all, no decisions required. But that simplicity has a cost measured in empty blood bank shelves.

Anesthesiologists are the logical group to lead this change because of their role in perioperative blood management and their presence during the highest-volume transfusion scenarios. The article calls for collaboration across specialties — with blood bank directors, surgeons, emergency physicians, and trauma teams — to make type-appropriate transfusion the default rather than the exception.

The message is blunt: donate more, especially if you are O-negative or O-positive. But also waste less. The patients most vulnerable to O-negative shortages are the ones who cannot receive any other type. Right now, they are competing for a resource that hospitals are giving to patients who have other options.