Anemia After Surgery

Causes and Treatment of Postoperative Anemia

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Anemia is a general term for an abnormally low number of red blood cells circulating through the body. Postoperative anemia is one of the known risks of surgery. A complete blood test (CBC) is a test run before and after surgery to check the levels of different types of cells in your blood. 

This test can tell us if blood loss during surgery was significant enough to warrant a transfusion, or if it was minor. Often the surgeon has a good idea of how much blood was lost during surgery, without testing, but will confirm with blood work. 


Anemia signs and symptoms can range from mild to severe, with fatigue and low energy being the most common. An increased heart rate, shortness of breath, headaches, dizziness, chest pain and pale skin are also possible.

If anemia is present prior to surgery, determining the cause and correcting the problem is important, especially if the anemia is severe. 

Preoperative anemia is associated with an increased risk of postoperative infection, respiratory failure, stroke, heart attack, and kidney dysfunction, particularly in older adults, according to research from Kings College London.


Anemia is broadly defined as a lower-than-normal number of red blood cells or hemoglobin (the molecule that transports oxygen in red blood cells).

Anemia happens when an individual either makes too few red blood cells, or is losing an abnormally high number of red blood cells through bleeding, or a combination of the two. Bleeding is common during and after surgery, can be mild to severe, and is absolutely able to cause anemia if enough blood is lost. 

The blood loss in surgery directly causes anemia as opposed to any particular problem with the body's ability to produce red blood cells or hemoglobin (such as occurs with hemolytic anemia or iron deficiency anemia).

Minimally invasive surgery naturally causes more blood loss than an open surgery in which blood transfusions may be needed during or after surgery. People with bleeding disorders like hemophilia are commonly advised to undergo laparoscopy ("keyhole surgery") rather than an open surgery if at all possible.

Trauma and trauma surgery are both associated with significant amounts of bleeding. Some injuries, such as a compound fracture of a major bone, are associated with significant blood loss. 


A CBC and hemoglobin test are the primary tests used to evaluate anemia prior to and following surgery.

For men, a normal hemoglobin level is 13.8 to 17.2 grams per deciliter (gm/dL), while a normal level for women is 12.1 to 15.1 gm/dL. 

With that being said, many surgeons won’t order a transfusion until the hemoglobin is in the 8.0 to 10.0 gm/dL range unless the blood loss is severely affecting your blood oxygen levels or respiration.

The risks associated with a blood transfusion are low. In rare instances, an allergic reaction may occur. Due to the routine screening of the blood supply in the United States, the risk of infections (such as viral hepatitis and HIV) is even lower. 


Anemia is treated based on the underlying cause. If an individual has iron deficiency anemia, for example, an iron supplement is typically the best option. 

For someone with significant blood loss from surgery or trauma, the replacement of the lost blood with a transfusion is the most direct and effective means of treatment.

A deficiency in the essential building blocks of blood, such as iron, vitamin B12, or folate, can make it difficult to rebuild the blood supply after surgery. Your doctor will routinely monitor your blood works to ensure you are better able to recover from a trauma or surgery.

For those who experience mild anemia after surgery, the treatment of choice is time. Over the weeks following surgery, the body will rebuild the blood supply. Fatigue and low energy levels will continue to improve, and you will usually back to your normal levels within a week or two depending on your surgery and postoperative care.

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