Blood loss is one of many situations that can cause anemia. Surgery involves blood loss. If you have anemia and undergo surgery, you may be at risk for serious complications.

Anemia is a condition in which your body doesn’t produce enough healthy red blood cells. As a result, hemoglobin (the protein in oxygen-rich blood) cannot move from your lungs to the rest of your body. If you have anemia, you might feel tired, weak, or even out of breath.

Anemia may contribute to surgery complications such as a higher risk of postoperative infection and the need for breathing support. Treating anemia before surgery may improve the outcome.

Here’s what you need to know about anemia and surgery, which procedures may treat anemia, and what guidelines your doctor may suggest following to avoid complications.

There are various types of anemia, including iron deficiency anemia, vitamin B12 deficiency anemia, and hemolytic anemia. Each has its own root cause and appropriate treatment.

There is no one surgery that can correct anemia. Instead, doctors may suggest other treatments and medical procedures, including:

Having anemia before surgery can be concerning to doctors because surgery involves blood loss. For example, major surgery is defined as surgery during which a person is expected to lose more than 500 milliliters of blood.

Blood loss on its own is a common cause of anemia. When your body loses too many red blood cells, your hemoglobin levels drop. This iron-rich protein is responsible for transporting oxygen from your lungs to the rest of your body.

If you have anemia and lose a lot of blood, your hemoglobin levels may drop dangerously low. This can lead to various complications and even death.

Undergoing surgery when you have anemia carries risks related to anesthesia as well. Depending on the type of anesthesia you receive, anesthesia can make anemia worse or prevent it from getting worse.

For example, neuraxial anesthesia may be more protective for people with anemia than general anesthesia. Some research suggests that neuraxial anesthesia may decrease bleeding by up to 30% by lowering blood pressure and venous tone (pressure in your veins).

The most common cause of anemia before surgery is iron deficiency.

However, blood loss is another common cause of anemia. While some people may lose blood during their menstrual cycle or due to a medical condition or injury, surgery can also cause excessive blood loss. Anemia before surgery is also more common in people who are older and in those who have chronic health conditions.

Undergoing surgery when you have anemia (from any cause) puts you at risk of serious complications, including:

Doctors previously thought that a blood transfusion during surgery could help treat issues related to anemia. But recent research has shown that blood transfusions during surgery may actually present more issues than they help.

Experts now recommend that hemoglobin levels be checked 6–8 weeks before surgery. The level should be greater than or equal to 130 grams per liter (g/L) for both men and women. If your level is lower than this, your doctor may suggest postponing your surgery.

Your doctor may also recommend treatment to address your hemoglobin levels. In most cases, oral iron supplements (those taken by mouth) can increase your hemoglobin and ferritin levels. Other types of anemia may be treated by addressing B12 deficiency, folate deficiency, kidney conditions, and other underlying conditions that cause inflammation and bleeding.

Once your hemoglobin levels are 130 g/L or greater, your doctor may reschedule your surgery.

Monitoring your hemoglobin levels after surgery is also important to healing. Postsurgery anemia is very common, but diagnosing and treating it is not necessarily at the forefront of care after surgery.

You may benefit from taking oral iron supplements or receiving an intravenous (IV) iron infusion after surgery. These supplements can address the iron deficiency you had before surgery and any other issues that may have resulted from blood loss during your procedure.

Postsurgery anemia may worsen during a hospital stay as a result of blood draws and blood testing. In fact, research suggests that blood loss from phlebotomy during the recovery period is a significant reason people develop anemia after surgery.

Inadequate diet and nutritional deficiencies are other common causes of anemia or worsened anemia after surgery.

Overall, your postoperative guidelines may include having fewer blood tests, taking prescription iron supplements, and focusing on healthy eating to address nutrient deficiencies. Your doctor may give you more specific guidelines that address your type of anemia and underlying conditions.

Experts estimate that around 40% of people who need major surgery have anemia before their surgeries. If you have questions about your anemia status, be sure to discuss your concerns with your doctor.

Something as simple as taking iron supplements may help increase your iron levels before your surgery. In other cases, you may need to take additional steps before and after surgery to reduce your chances of developing serious complications.