Can you have surgery if you’re anemic?

Surgery can go forward when you are anemic, but operating on a low hemoglobin level raises the odds of complications, longer hospital stays, and even death. Roughly a third of patients showing up for planned surgery already have some degree of anemia, and surgeons know this well enough that an entire field called Patient Blood Management has grown up around the problem. Whether your operation should be delayed, how your anemia should be treated beforehand, and what extra precautions the surgical team will take all depend on the severity of your anemia, the type of surgery, and how urgently it needs to happen.

How Common Anemia Is Before Surgery

If you are told your blood counts are low before an operation, you are far from alone. A large retrospective study at a university hospital found that about a third of patients scheduled for elective general surgery were anemic, with most of those cases falling in the mild range.¹ A study at a hospital in Ethiopia put the number even higher at roughly 37%, with about two-thirds of those cases classified as mild.² An international study spanning 27 countries and nearly 39,000 patients found 30% were anemic before surgery.³ The causes vary: chronic disease, iron deficiency, kidney problems, nutritional gaps, or simply heavy menstrual bleeding in premenopausal women. Whatever the reason, the proportion of surgical patients walking in with low hemoglobin is large enough that most surgical teams have protocols for dealing with it.

What Risks Anemia Adds to Surgery

Going under the knife with a low hemoglobin level is not automatically dangerous, but the data consistently show it tilts the odds against you. A meta-analysis pooling results from many studies found that preoperative anemia was associated with roughly triple the odds of death after surgery and nearly quadruple the odds of acute kidney injury.⁴ Infection risk also climbed, roughly doubling compared to patients with normal hemoglobin levels. Importantly, these risks scale with severity. The international study mentioned earlier found that patients with moderate anemia had about 2.7 times the odds of dying within 30 days, and those with severe anemia had about four times the odds, compared with patients whose blood counts were normal.³ Complication rates in general rose in step with worsening anemia.

What makes anemia so risky during surgery is straightforward: your blood carries less oxygen. When a surgeon cuts tissue, there is blood loss, and a body that was already starting from a deficit has less margin. The heart works harder to circulate the oxygen that remains, organs that depend on steady oxygen delivery (the kidneys, the brain) become vulnerable, and wound healing slows when tissue does not get the oxygen it needs to repair itself.

The Difference Between Elective and Emergency Surgery

If your surgery is planned weeks or months ahead, you have a window to do something about anemia beforehand. Guidelines emphasize that anemia should be detected as soon as possible after you are listed for surgery so that there is enough time to treat it.⁵ For a hip replacement or a bowel resection scheduled two months out, that gives your medical team real room to investigate the cause and raise your hemoglobin.

Emergency surgery is a different story. If you have a ruptured appendix or a bowel obstruction, the operation cannot wait for your hemoglobin to improve. In those situations, the surgical team manages the anemia in real time with transfusions if needed, monitors you more closely during and after the procedure, and addresses the anemia in the recovery phase. Research on emergency laparotomy patients has found that while guidance exists for giving iron after surgery and investigating the underlying cause, communication to primary-care doctors about follow-up anemia management is often lacking.⁶ If you have had emergency surgery and you know you were anemic going in, it is worth asking your doctor explicitly about a follow-up plan for your blood counts.

How Surgeons Decide Whether to Delay

There is no single hemoglobin number that serves as an absolute cutoff for surgery. The decision depends on several factors: how low your hemoglobin actually is, whether your anemia is correctable in a reasonable timeframe, and how urgently the surgery needs to happen. A patient with mild anemia heading into a minor procedure carries a very different risk profile from someone with severe anemia facing open-heart surgery.

For elective operations, many surgical teams use a hemoglobin below about 12 grams per deciliter as a trigger to investigate further. A common diagnostic protocol checks whether you are iron-deficient by looking at ferritin levels and a measure called transferrin saturation.⁷ If the cause is iron deficiency, treatment is available and usually effective. If the cause is something else, such as chronic kidney disease, inflammatory conditions, or an undiagnosed bleed, the treatment and timeline change accordingly. The goal is not necessarily to bring your hemoglobin back to textbook normal, but to get it high enough to give you a safer surgical margin.

Raising Your Hemoglobin Before Surgery

Iron supplementation is the first line of treatment for iron-deficiency anemia before surgery, and the question is usually whether to go with oral pills or intravenous infusions. A meta-analysis of 12 randomized trials comparing the two found that intravenous iron raised hemoglobin by about 0.77 grams per deciliter more than oral iron and was roughly twice as likely to get patients to their target hemoglobin level before the operation.⁸ The catch: neither approach clearly reduced the need for blood transfusion during surgery itself in that analysis. Intravenous iron is faster, which matters when the surgical date is only a few weeks away and oral iron would not have time to work. Oral iron, while cheaper and simpler, takes longer and causes gut side effects that lead some people to stop taking it.

For patients whose anemia is more stubborn, doctors sometimes add a hormone that stimulates red blood cell production. A Cochrane review found moderate-quality evidence that this approach, combined with iron supplementation, reduces the need for blood transfusion during non-cardiac surgery, and at higher doses it meaningfully raises hemoglobin before the operation.⁹ This therapy is not used routinely for everyone; it tends to be reserved for patients who either cannot tolerate iron alone, do not respond to it, or face a surgery with expected heavy blood loss.

Blood Transfusions and When They Are Used

If your hemoglobin drops low enough during or after surgery, a blood transfusion becomes necessary. But transfusions themselves carry risks, so there has been a decades-long debate about exactly when to give one. The short version: most evidence supports a “restrictive” strategy, meaning doctors wait until hemoglobin drops to a lower threshold before transfusing, rather than topping up the tank at the first sign of a dip.

In orthopedic surgery, a systematic review found no meaningful difference in death rates, infection, heart attack, or heart failure between restrictive and liberal transfusion thresholds for patients undergoing hip or knee procedures.¹⁰ For patients with heart attacks and anemia, the picture is slightly more complicated. One large trial found that a restrictive strategy was noninferior to a liberal one, meaning the outcomes were not significantly worse.¹¹ However, a larger subsequent trial in similar patients saw a trend toward more deaths and heart attacks with the restrictive approach that just missed reaching statistical significance.¹² This means patients with active heart disease may benefit from a slightly higher transfusion trigger, and your surgical team should know about any cardiac history.

Transfusions are not risk-free. They have been linked to increased infection rates after major surgery and to immune suppression that can affect recovery.¹³ The risk of transmitting viral infections through blood products has dropped sharply over the decades thanks to better screening, but bacterial contamination remains the most common transfusion-related adverse event. Evidence also suggests a link between perioperative blood transfusion and poorer long-term outcomes, including a higher rate of cancer recurrence after operations intended to cure cancer.¹⁴ None of this means you should refuse a transfusion when you genuinely need one, but it does explain why surgeons try to avoid unnecessary ones.

Techniques to Reduce Blood Loss During Surgery

Modern surgical teams have a growing toolkit to keep blood where it belongs. Cell salvage, or “cell saving,” collects blood lost during an operation, washes it, and returns it to you. This effectively recycles your own red blood cells. Studies in hip replacement surgery have found intraoperative cell salvage to be an effective method of reducing reliance on donated blood.¹⁵ The primary goal of all autologous blood salvage techniques is to reduce or eliminate the need for banked blood transfusions and their associated risks.¹⁶

Drugs also play a role. Tranexamic acid, a medication that helps blood clot more effectively, has been shown to substantially reduce postoperative bleeding. In one study of patients undergoing hip and femoral surgeries, those who received tranexamic acid lost less than half the blood in their surgical drains compared with patients who did not receive it, and the drop in hemoglobin after surgery was dramatically smaller.¹⁷ Fewer of those patients needed transfusions afterward. Tranexamic acid is now widely used across orthopedic, cardiac, and trauma surgery.

What Happens After Surgery If You Are Still Anemic

Anemia does not just matter before and during surgery. It has a real impact on recovery. An international study of patients who had major abdominal surgery found that those who were anemic after the operation were significantly more likely to be readmitted to hospital within 30 days. The risk of readmission rose with the severity of the anemia: moderate-to-severe postoperative anemia roughly doubled the risk compared to patients without anemia, while even mild anemia raised it by about 40%.¹⁸

Functional recovery can also lag. A study of patients after lumbar spine fusion found that those discharged with lower hemoglobin had higher complication rates across the board, including higher 90-day readmission rates, more infections, and more gastrointestinal problems. They also reported more pain and worse functional scores at follow-up visits.¹⁹ If you are heading home from the hospital and your blood counts are still low, ask about an iron supplementation plan. Waiting for your levels to drift back up on their own can mean weeks of unnecessary fatigue and slower healing.

Anemia and Postoperative Delirium in Older Adults

One complication that deserves special mention is postoperative delirium, especially for older patients. Delirium after surgery means a sudden episode of confusion, disorientation, and altered awareness, and it can be distressing for patients and families. A large retrospective study of elderly patients undergoing non-cardiac surgery found that preoperative anemia was independently associated with about a 42% higher risk of delirium, and moderate-to-severe anemia raised the odds by 70%.²⁰ Another study looking specifically at older patients undergoing hip replacement found that moderate-to-severe anemia more than tripled the odds of postoperative delirium.²¹ A multicenter study of hip fracture patients echoed these findings, identifying severe anemia as an independent predictor of delirium.²²

The brain is extraordinarily hungry for oxygen, and when oxygen delivery falls because of low hemoglobin, it becomes vulnerable. For families with an older relative facing surgery, asking about preoperative hemoglobin and whether it can be optimized is a concrete step that may reduce the risk of a frightening and sometimes prolonged episode of confusion after the operation.

Sex Differences in How Anemia Is Caught and Treated

Anemia before surgery is not detected and managed equally across sexes, and the gap is worth understanding. Traditionally, the hemoglobin threshold used to define anemia has been lower for women than for men. One study found that when the threshold was raised to 13 grams per deciliter for both sexes, the proportion of women identified as anemic nearly doubled, from about 23% to 49%.²³ A large group of women with hemoglobin between 12 and 12.9 were slipping through the net under the older definition, and these borderline-anemic women were actually the most likely among women to end up being transfused during their hospital stay.

A separate multicentre study found that women were twice as likely as men to have a hemoglobin below 13 grams per deciliter, yet they were also over three times more likely to remain untransfused despite being anemic.²⁴ This suggests that clinicians may apply different attitudes to what counts as “low enough to worry about” in women, even though the data show that women with borderline-low hemoglobin tend to have longer hospital stays and use more blood products when they do get transfused. If you are a woman being told your hemoglobin is “fine” at 12 before a major surgery, it is reasonable to ask whether optimization would improve your outcome.

Surgery Without Blood Transfusion

Some patients cannot or will not receive blood transfusions, whether for religious reasons, personal conviction, or medical conditions that make transfusion especially risky. A whole discipline called “bloodless medicine and surgery” has developed to serve them. The approach focuses on building up hemoglobin before surgery through aggressive iron and hormone therapy, minimizing blood loss during the procedure using surgical technique and drugs like tranexamic acid, and supporting the body’s oxygen use afterward with measures like supplemental oxygen and minimizing unnecessary blood draws.²⁵

Programs that specialize in bloodless surgery emphasize early screening and management of anemia, establishing the patient’s wishes clearly before the operation, and integrating those wishes into every stage of care.²⁶ Coordinated care across the entire surgical team is central to making it work safely.²⁷ Interestingly, many of the techniques pioneered in bloodless surgery have since been adopted into mainstream surgical practice because they improve outcomes for everyone, not just patients who decline transfusion. The lesson is that optimizing hemoglobin before surgery, minimizing surgical blood loss, and being thoughtful about when transfusion is truly necessary is good medicine across the board.

Why Hospitals Are Investing in Preoperative Anemia Programs

Treating anemia before surgery is not just better for patients. It also saves money. Studies modeling the economic impact of Patient Blood Management programs have found that managing anemia before surgery reduces complications, shortens hospital stays, decreases time in intensive care, and lowers the number of transfusions needed. One analysis of a Turkish hospital’s cardiovascular surgery department found that implementing a blood management program in a single department saved the equivalent of over €400,000 in 20 months, driven by fewer complications and fewer transfusions.²⁸ A broader Turkish analysis estimated that Patient Blood Management was associated with thousands of avoided adverse events and meaningful cost reductions in both cardiac and non-cardiac surgery.²⁹ A Romanian analysis reached similar conclusions, attributing savings primarily to shorter hospital stays and lower overhead costs when complications were avoided.³⁰

This matters for patients because it means the trend in modern surgery is moving firmly toward catching and treating anemia before you reach the operating room. If your surgical team does not mention your blood counts during the preoperative workup, bring it up yourself. A simple blood test weeks before surgery can identify a problem that is both common and fixable, and the downstream benefits for your safety, recovery, and even hospital costs are well documented.