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. Anemia after surgery (called "postoperative anemia") is one of the known risks of surgery

Due to the increased risk of anemia after surgery, doctors generally run a complete blood count (CBC) before and after surgery. This blood test checks the levels of different 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 blood transfusion (when you receive donated blood through an IV). While a surgeon often has a good idea of how much blood you lost during surgery, a blood test can more objectively assess the degree of postoperative anemia. 

This article explains postoperative anemia symptoms, causes, diagnosis, and treatment.

symptoms of anemia
Verywell / Theresa Chiechi

Anemia Symptoms

Anemia signs and symptoms can range from mild to severe. Unfortunately, postoperative anemia is not uncommon, affecting around 90% of people following surgery. Fortunately, the problem tends to be transient (short-lived) and does not usually require a transfusion.

Postoperative anemia symptoms may include:

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

If anemia is present before surgery, determining the cause and correcting the problem is essential, especially if the anemia is severe.

According to a 2013 review in the Journal of the Royal Society of Medicine, preoperative anemia is associated with an increased risk of postoperative infection, respiratory failure, stroke, heart attack, and kidney failure, particularly in older adults.

Causes and Risk Factors

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 makes too few red blood cells or loses an abnormally high number of red blood cells through bleeding. Bleeding is common during and after surgery and can range from mild to life-threatening.

Higher Risk

Some health conditions, injuries, and types of surgery increase the risk of bleeding and thus postoperative anemia, including:

Lowering Risk

Minimally invasive surgery involving smaller incisions causes less blood loss than open surgery. Therefore, surgeons commonly advise people with bleeding disorders to undergo laparoscopy, also called "keyhole surgery," rather than an open surgery if at all possible.

During laparoscopic procedures, surgeons thread cameras through small incisions that allow them to see what they are working on. Due to the smaller incision size, this often results in less blood loss.

Today, surgeons can perform an increasing number of surgeries laparoscopically. Less invasive surgical incisions reduce the risk of complications and shorten recovery times.


Anemia occurs when there are too few red blood cells. Often this results from bleeding. Open surgery, trauma surgery, and having a bleeding disorder increase your risk of postoperative anemia. Laparoscopic surgery lowers the risk.


A CBC, which includes a hemoglobin test, is the primary test used to evaluate anemia before and after surgery. Each test in the CBC 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 indicate 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 short-lived in healthy individuals, a transfusion is not indicated until the hemoglobin is below 7 gm/dL or 8 gm/dL in people with heart conditions.


Anemia treatment varies depending on the underlying cause. For example, if an individual has iron deficiency anemia, an iron supplement is typically the best option. However, if anemia occurs due to blood loss from surgery, treatment may require a different approach.


A blood transfusion is the most immediate and effective treatment for someone with significant blood loss from surgery or trauma.

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.

Watchful Waiting

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. Therefore, your healthcare provider will routinely monitor your blood work to ensure you can recover from a trauma or surgery.

The treatment is usually watchful waiting for those who experience mild anemia after surgery. Over the weeks following surgery, your body will rebuild your blood supply. 

Fatigue and low energy levels usually improve over time. Depending on your surgery and postoperative care, you will likely be back to your normal levels within a week or two.


Treatment for anemia depends on the cause. With postoperative anemia, blood transfusion and watchful waiting are the most common approaches.


Postoperative anemia sometimes occurs following surgery as a result of blood loss. Open surgery, trauma surgery, and having a bleeding disorder increase your risk of postoperative anemia. Less invasive techniques, such as laparoscopic surgery, lower the risk. Treatment for postoperative anemia sometimes requires a blood transfusion, but often watchful waiting is appropriate.

If you're worried that you could need a blood transfusion after surgery, talk to your surgeon about autologous blood donation. In this procedure, your blood is taken before surgery and used after surgery if needed. This process eliminates any risk of disease transmission.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Jennifer Whitlock, RN, MSN, FN
Jennifer Whitlock, RN, MSN, FNP-C, is a board-certified family nurse practitioner. She has experience in primary care and hospital medicine.