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 (RBC) 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, including the RBC count

A CBC can tell the surgical team if blood loss during surgery was significant enough to warrant a transfusion. Oftentimes, the surgeon has a good idea of how much blood was lost during surgery but will assess the degree of postoperative anemia with blood work. 

symptoms of anemia
Verywell / Theresa Chiechi


Anemia signs and symptoms can range from mild to severe. Postoperative anemia is not all that uncommon, affecting around 90% of people following surgery, although the problem tends to be transient and will not require a transfusion.

If postoperative anemia does develop, symptoms may include:

  • Fatigue
  • Weakness
  • Increased heart rate
  • Shortness of breath
  • Headaches
  • Dizziness
  • Chest pain
  • Pale skin

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 failure, particularly in older adults, according to a 2013 review in the Journal of the Royal Society of Medicine.


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 develops when an individual either makes too few red blood cells and/or is losing an abnormally high number of red blood cells through bleeding. Bleeding is common during and after surgery and can range in severity from mild to life-threatening.

Minimally invasive surgery involving smaller incisions causes less blood loss than open surgery. People with bleeding disorders like hemophilia are commonly advised to undergo laparoscopy ("keyhole surgery") rather than an open surgery if at all possible. Today, an increasing number of surgeries can be performed laparoscopically, reducing the risk of complications as well as recovery times.

Trauma surgery is 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. Each test has a reference range of values—including an upper and lower value—between which the count is considered "normal." RBC and hemoglobin values below the reference range are indicative of anemia.

Test Group Normal Reference Range
RBC Men 4.7 to 6.1 million cells per microliter (mcL)
  Women 4.2 to 5.4 million mcL
  Children 4.0 to 5.5 million mcL
Hemoglobin Men 14 to 18 grams per deciliter (gm/dL)
  Women 12 to 16 gm/dL
  Children 11 to 13 gm/dL

Because postoperative anemia tends to be transient in healthy individuals, many surgeons won’t order a transfusion until the hemoglobin is in the 8.0 to 10.0 gm/dL range and the blood loss is severely affecting blood oxygen levels or respiration.


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, a blood transfusion is the most direct and effective means of treatment.

The risks associated with blood transfusions 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 extremely low.

According to the American Red Cross, the risk of HIV, hepatitis C, and hepatitis B from a blood transfusion is one per 2.3 million, 2.6 million, and 1.5 million donations respectively.

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 healthcare provider 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.

A Word From Verywell

In the event that a blood transfusion is needed, some people prepare by making an autologous blood donation, in which the patient's own blood is taken before surgery and used after surgery if needed. The eliminates any risk of disease transmission.

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6 Sources
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