Anemia After Surgery

Postoperative Anemia: What You Should Know

Blood Tests Image
Blood Tests. Image: © Nicholas Everleigh/Getty Images

Question: I just had surgery and now my blood tests are showing that I have anemia and they were fine before I had surgery. Did surgery cause my anemia?

Answer:  While I cannot be absolutely certain, you are probably experiencing something called postoperative anemia, which is a temporary condition. The short answer to your question is that surgery probably did cause your anemia, but your body is prepared to fix the problem.

  To put it another way, surgery may have caused your anemia by causing bleeding, but it didn’t damage your body’s ability to create enough healthy red blood cells. 

That was as clear as mud, wasn’t it?  Let me explain a bit about what anemia is, what causes it and why surgery could temporarily cause you to be anemic.


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 CBC is a test frequently 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. 

Signs and Symptoms

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 is the anemia is severe. 


There are many causes of anemia, some conditions prevent the body from making enough red blood cells, or the red blood cells that are made are undersized.

  Two common causes of anemia are thalassemia, an inherited condition, and iron deficiency.  Other types of anemia may cause the body to produce oversized red blood cells.

You can make an ample supply of perfect red blood cells and still be anemic if you are bleeding.  Some women have anemia associated with heavy menstrual bleeding, but trauma or surgery is certain to cause blood loss.  Minimally invasive surgery is expected to cause less blood loss, while open heart surgery is often expected to create a need for a blood transfusion during or after surgery.  Some patients who know that they might need a transfusion due to their surgery may elect to use bloodless surgery techniques to avoid the risks of transfusion. 

Trauma, and trauma surgery, is associated with significant amounts of bleeding, which can vary depending on the nature of the trauma.  Some injuries, such as a broken femur, are closely associated with blood loss. 


To treat anemia, knowing the cause of the problem is essential.  If an individual has iron deficiency anemia, an iron supplement is the best treatment.  For someone with blood loss, however, iron won’t really solve the problem--a transfusion is needed if the blood loss is severe enough.

  So identifying the cause is the first step to effectively treating anemia.  For postoperative anemia, making sure there is no more bleeding is the first step, followed by a transfusion, giving the body time to recover or both.

Determining Severity

In the case of postoperative anemia, feeling the symptoms of anemia is just one part of determining if you need a transfusion. A blood test called a Complete Blood Count (CBC) is the best way to determine the severity of the condition.  One of the tests in a complete blood count is the hemoglobin level, a low hemoglobin result indicates anemia.  

For men, a normal hemoglobin level is 13.8 to 17.2 gm/dl while the normal level for a female is 12.1 to 15.1 gm/dL.

  That said, many surgeons won’t order a transfusion until the hemoglobin is in the 8-10 range unless the patient is experiencing at least moderate symptoms, because there are risks associated with blood transfusions. 

For many patients who experience mild anemia after surgery the treatment of choice is time.  Over the weeks following surgery, the body rebuilds the supply of red blood cells until a normal level is achieved.  Feelings of fatigue and low energy continue to slowly improve as red blood cell levels improve.  It is important to remember that feeling tired is common when recovering from surgery, as surgery is very stressful for the body and can lead to feeling tired with even minor activity. 


Anemia. Medline Plus.  Accessed April, 2014.