Anemia After Surgery: What to Know

Anemia is a condition in which your body does not have enough red blood cells (RBC) to carry oxygen to all your cells. Postoperative anemia refers to a drop in red blood cells that occurs as a result of blood loss during surgery. It is a common risk of surgery that can result in a longer recovery and increase the risk of complications.

If you have anemia, you might feel weak, short of breath, or lightheaded. Some people with anemia have headaches, pale skin, or cold hands and feet. In most cases, postoperative anemia is temporary. More severe cases of postoperative anemia may need to be treated with a blood transfusion, in which donated blood is administered through an IV.

This article explains what postoperative anemia is, the symptoms it may cause, and why exactly it happens due to surgery. It also discusses how postoperative anemia is diagnosed and treated.

What Are the Symptoms of Postoperative Anemia?

Anemia signs and symptoms can range from mild to severe. Postoperative anemia is common, affecting around 90% of people following surgery. Fortunately, it 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 (preoperative anemia), determining the cause and correcting the problem is essential, especially if the anemia is severe.

What Happens if Your Hemoglobin is Low After Surgery?

Postoperative anemia increases the risk of complications during the recovery period. People with postoperative anemia are more likely to experience:

• Insufficient blood flow in the body (hemodynamic instability)
• A longer surgical recovery
• Longer need for breathing assistance with a machine
• Increased need for a blood transfusion
• Re-do surgery or readmission into the hospital
• Heart attack (myocardial infarction)
• Kidney injury
• Delirium, characterized by confused thinking, disorientation, and a lack of awareness of one's surroundings

Furthermore, those who require a blood transfusion due to postoperative anemia have an increased risk of:

• Infections
• Immune reactions to the donated blood

Additionally, having postoperative anemia or a blood transfusion increases the risk of death within the first 30 days after surgery.

Causes and Risk Factors of Postoperative Anemia

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:

• Open surgery (a surgery where the skin is opened with a scalpel)
• Trauma surgery
• A compound fracture of a major bone
• People with bleeding disorders like hemophilia (a condition that prevents blood from clotting effectively)

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.

How is Postoperative Anemia Diagnosed?

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.

Symptoms of severe anemia can include:

• Blue color in the whites of the eyes
• Brittle nails
• Pica syndrome, characterized by a desire to eat ice or other non-food items
• Lightheadedness upon standing
• Pale skin
• Shortness of breath with mild activity or even when at rest
• Sore or inflamed tongue
• Mouth ulcers
• Abnormal or increased menstrual bleeding in females
• Loss of sexual desire in males
  

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.

What Hemoglobin is Too Low for Surgery?

In adults, a hemoglobin level below 13 gm/dL is considered preoperative anemia. Having preoperative anemia increases the risk of surgical complications, as well as the need for a blood transfusion after surgery. A discovery of anemia in routine preoperative blood tests will prompt treatment to correct hemoglobin levels well before surgery.

How is Postoperative Anemia Treated?

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.

Transfusion

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.

Watchful Waiting

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.

Iron Supplements

Iron supplements are commonly prescribed to people with anemia. The body uses iron to make hemoglobin and myoglobin, two proteins that are essential for circulating oxygen through the body.

Iron supplements come in several forms, including ferrous iron salts, ferric iron salts, ferric citrate, and ferric sulfate. Among them, ferrous iron has the highest bioavailability, meaning that it is easiest for your body to digest, absorb, and make use of.

Keep in mind that high doses of supplemental iron can cause gastrointestinal side effects, such as nausea or constipation. So it's important to only take the amount recommended by your healthcare provider.

Summary

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.