What You Need to Know About Blood Transfusions, Donation, and Typing

The need for blood transfusions during or immediately following surgery is not uncommon. Bleeding during surgery is unavoidable, and in some cases, enough bleeding to require a transfusion is expected. In severe cases, such as hemorrhage during a procedure, blood transfusions may be given during the procedure. For other patients, bleeding during surgery may be slightly greater than normal, making a transfusion necessary during recovery.

blood transfusion
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The best indication of whether a blood transfusion is needed is the CBC blood test. Hemoglobin and hematocrit levels can show if a transfusion is recommended, absolutely necessary, or not needed.

A person who needs a blood transfusion may exhibit signs and experience symptoms of blood loss, commonly known as anemia. In addition to the changes seen when blood is tested, someone who needs a transfusion often feels weak, gets winded very easily, and may appear pale.


A blood transfusion, even when necessary, is not without risks. The risks of blood transfusion range from a small bruise at the IV site to a very small risk of death. For this reason, the decision to have a blood transfusion is a serious one and should be made thoughtfully.


Some patients choose to refuse blood transfusions for religious reasons, or because they feel the risks of a transfusion are too high. Some of these patients choose autologous blood transfusion to minimize risks or plan a bloodless surgery when possible. Medications can help the body make blood more quickly than normal. Procrit, or Erythropoietin, stimulates red blood cell production and may make a transfusion unnecessary.

Blood Typing

In order to receive a blood transfusion, your blood type must be determined. In an emergency, O- blood may be given before your blood type is known, but once blood typing is complete, your blood type will be given to you. Blood typing is the procedure that is done to determine your blood type. Your blood will fall into one of four categories, A, B, AB or O.

In addition to a blood type, your Rh factor will also be determined during blood typing. Rh factors are noted as positive or negative, so if you are an A blood type, you could be A+ or A-. If you are Rh positive, you can receive both positive and negative blood. If you are negative, you can only receive Rh negative blood.

Rh incompatibility between a donor and transfusion patient is avoided by blood typing, but in some cases, expectant mothers can experience Rh incompatibility. This happens when the father of the fetus is Rh+, the fetus is Rh+ and the mother is Rh-. In the past, this could lead to a fetal demise, however, nearly all cases of incompatibility are now treated with injections of the medication RhoGAMM.

Universal Donors and Universal Recipients

A universal donor is an individual with a blood type that can be given to any patient without rejecting it due to incompatible antigens. In addition to being a universal blood donor, universal donors are also universal organ donors.

A universal recipient is an individual with a blood type that allows them to receive a transfusion from any blood type, without experiencing a reaction caused by antigens. They can also accept an organ transplant from an individual with any blood type.

Eligibility for Donating Blood

Donated blood is always in demand and maintaining an adequate supply depends upon the generosity of the public. One person who begins donating in their teen years can donate over 40 gallons of life-saving blood in their lifetime, which is especially important when you consider that one trauma victim may be transfused with 40 or more units of blood.

In order to donate blood, you must be healthy, at least 17 years old and weigh no less than 110 pounds. In addition to the minimum requirements, the American Red Cross maintains a list of eligibility criterion (conditions and social history that may prohibit donation).

Don't worry if you are not sure if you qualify as a donor, the nurse at the blood donation center will discuss eligibility with you and help you determine if you are able to be a donor.

Conditions That Prevent Blood Donation

  • HIV
  • Hepatitis
  • Pregnancy
  • Active Tuberculosis
  • Fever
  • Active Infection
  • Travel to countries with possible exposure to malaria and other infections
  • Cancer

The CDC recently changed their rules regarding blood donation by gay men. In the past, gay men were considered high risk and were not permitted to donate blood for the general population. This is no longer true. 

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.
  • Eligibility Criteria. American Red Cross. 
  • Risks Associated With Transfusion. United Blood Services. 
  • The Continuing Risk of Transfusion-Transmitted Infections. M. Blajchman, C. Vamvakas, N Engl J Med 2006.

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.