What must be done before a blood transfusion?

Blood transfusions are a common medical procedure used to replace blood or blood components lost through bleeding. They involve transferring blood or parts of blood from one person (the donor) into the bloodstream of another person (the recipient). Blood transfusions can be life-saving in cases of severe blood loss from trauma, surgery, childbirth complications, and blood disorders. However, blood transfusions also carry risks and must be done with care to avoid complications. There are important steps that must be taken prior to a blood transfusion to ensure it is done safely.

Assessing the Need for Transfusion

The first step before a blood transfusion is determining whether one is truly needed or not. Blood transfusions should not be given unless absolutely necessary, as there are always risks involved. Doctors will consider the patient’s current blood counts, medical history, physical condition, and symptoms to decide if a transfusion is required.

Alternative treatments are considered before resorting to a transfusion. These may include medications to stimulate red blood cell production, intravenous fluids, nutrition supplements, oxygen therapy, or procedures to control active bleeding. If the patient’s condition is stable and they are not experiencing severe symptoms, a transfusion may not be immediately needed.

However, transfusions are warranted in cases of severe anemia with low hemoglobin/hematocrit levels, active bleeding, shock due to blood loss, or unstable cardiovascular conditions. Doctors must weigh the benefits against the potential risks for each individual patient.

Blood Typing and Cross-matching

If a transfusion is deemed necessary, the next vital step is blood typing and cross-matching the donor’s blood with the recipient’s blood. Blood types are classified according to the presence or absence of specific antigens on the red blood cells’ surfaces. The common ABO blood group system consists of types A, B, AB, and O.

Donor blood must be cross-matched with the recipient’s blood type to check compatibility and prevent transfusion reactions. First, a blood sample from the intended recipient is tested to determine their ABO group and Rh type. Next, the donor’s blood is tested to confirm the blood group. Then, a cross-matching procedure is done to mix the donor and recipient blood samples and check for agglutination, or clumping, of red blood cells.

If agglutination occurs, it means the blood types are incompatible and those units should not be used. Cross-matching ensures that compatible blood is selected for transfusion. It is a crucial safety step that must never be skipped.

Screening Donated Blood for Infections

All blood intended for transfusion must be tested for infections that can be transmitted through blood. Donated blood is screened for a number of viral, bacterial, and parasitic diseases including:


HIV is the virus that causes AIDS. All donated blood is screened for HIV using nucleic acid testing to detect the viral RNA.

Hepatitis B and C

These viruses cause liver inflammation and damage. Blood is tested for hepatitis B surface antigen and hepatitis C antibody or RNA.


Caused by the bacterium Treponema pallidum. The blood is tested for syphilis antibodies.


HTLV stands for human T-lymphotropic virus, which can cause leukemia. Testing identifies HTLV antibodies.

West Nile Virus

Mosquito-borne virus that can infect blood donors. The blood is tested for West Nile virus RNA.

Chagas Disease

Caused by the parasite Trypanosoma cruzi and transmitted by triatomine insects. Blood is tested for T. cruzi antibodies.


CMV is a common herpesvirus that can be transmitted through transfusions to premature infants. CMV antibody screening identifies CMV-negative blood products to use for at-risk newborns.

Any donated blood testing positive for these infections is discarded and not used. This rigorous screening is essential to prevent transmitting these diseases to transfusion recipients.

Procuring Appropriate Blood Products

In addition to whole blood, there are different types of blood component products that may be used for transfusion based on the patient’s specific needs:

– Packed Red Blood Cells (PRBCs) – Contains red cells with the plasma removed; used to treat anemia.

– Platelets – Used to control bleeding in thrombocytopenia.

– Plasma – The fluid portion of blood; used to replace clotting factors in coagulopathies.

– Cryoprecipitate – Source of clotting factors, including fibrinogen; given for hypofibrinogenemia.

The physician must determine which blood component is appropriate for the patient and order the correct product for transfusion. Blood banks and transfusion services must have rigorous procedures for procuring, handling, and verifying these products.

Proper storage conditions must be maintained. For example, platelets must be stored at room temperature with continuous gentle agitation, while PRBCs and plasma are stored refrigerated. Verification checks prevent misidentification and transfusion of incorrect units.

Informed Consent

As with any medical procedure, the patient must be informed about the risks and benefits of transfusion and give their permission prior to proceeding. This is especially important given the potential for adverse reactions.

The doctor should explain:

– Why the transfusion is recommended based on the patient’s condition.

– Benefits the patient is likely to gain.

– Risks such as fever, allergic reactions, infectious disease transmission and hemolytic reactions.

– Alternatives to transfusion if available.

After the doctor provides information and answers questions, the patient or legal authorized representative signs an informed consent form. Understanding the procedure and its implications is an ethical and legal requirement before transfusing blood products.

Patient Testing Before Transfusion

Prior to starting the actual blood transfusion, pre-transfusion testing must be done at the patient’s bedside to confirm it remains appropriate and safe to proceed. This typically involves:

Repeat ABO/Rh Typing

The patient has a blood sample drawn and typed again to verify their ABO and Rh blood group. This serves as a critical double check.

Antibody Screen

The patient’s new blood sample is tested for abnormal red blood cell antibodies that could cause a hemolytic transfusion reaction if incompatible blood is given.

Vital Signs

Temperature, pulse, respirations and blood pressure are checked for baseline. The patient is monitored for fever or other signs of illness. Transfusions are avoided if the patient has an active infection.

Documentation Check

The patient’s medical record is reviewed to verify their identifiers match the labeled blood product. The product type, donor identities, expiration dates and special requirements are confirmed.

Only when all these pre-transfusion tests are completed and confirmed acceptable is the blood product approved for transfusion. This bedside verification prevents many errors and adverse events.

Intravenous Access Establishment

Before starting the infusion, vascular access must be established if the patient does not already have an appropriate IV line. Good venous access in a large vein is needed for efficient infusion of blood products.

The IV is started using sterile technique and the line is flushed with sterile saline. For adults, blood is typically infused through a large (16-18 gauge) catheter placed in a central vein or antecubital fossa of the arm. For children and infants, smaller peripheral veins may be used.

If multiple blood products will be transfused, separate IV catheters are ideal to prevent interaction between incompatible products. Once venous access is obtained and confirmed functional, the blood product can be brought to the bedside and connected.

Transfusion Administration

With all the above steps completed, the blood transfusion can finally commence. Correct administration technique helps avoid complications:

– The expiration date is confirmed again before hanging the blood bag and starting infusion. Outdated units are never transfused.

– The product is administered through an IV infusion pump to control and regulate flow rates. Starting slowly helps detect problems.

– Vital signs are rechecked at the start, periodically during, and at end of transfusion.

– The patient is monitored closely for signs of adverse reactions throughout the process.

– IV sites are inspected frequently to ensure no infiltration or leakage occurs.

– PRBC transfusions usually take 1-4 hours. Platelet transfusions are typically complete in 30 minutes up to 2 hours.

– When finished, the IV line is flushed with normal saline to infuse any remaining blood in tubing into the patient.

Adhering to proper administration protocols is vital for safe, effective blood transfusions and prevention of complications.

Post-Transfusion Testing and Monitoring

Even after completing the transfusion, there are important steps to take:

Post-Transfusion Blood Samples

New blood samples are drawn from the patient for testing. A complete blood count assesses their response and whether additional transfusions are needed. A type and screen looks for new irregular antibodies that may have formed.

Vital Signs

Temperature, pulse and blood pressure continue to be monitored for several hours post-transfusion. Fever and drops in blood pressure can signal issues.

Symptom Checks

The patient is observed closely for signs of hemolytic reaction, allergic reaction, circulatory overload or sepsis. Shortness of breath, flank pain and dark urine may be warning signs.

Delayed Serious Hazards of Transfusion (SHOT) Reporting

Any suspected adverse reaction is reported per SHOT protocols for timely investigation. Review may reveal needs to modify policies and prevent future events.

Proper follow-up helps determine the efficacy of the transfusion, spot any complications, and guide any further treatment needed.

Transfusion Documentation

Complete documentation in the medical record is imperative for all transfusions. Details must be recorded regarding:

– Justification for transfusion.

– Informed consent obtained.

– Blood units transfused including product descriptions, ISBT numbers, donor IDs, expiration dates, times collected and infusion start/stop times.

– Vital signs pre, intra, and post-transfusion.

– Adverse reactions observed, if any.

– Patient’s response to transfusion.

Thorough documentation provides a legal record showing proper transfusion protocols were followed. It also aids in tracing blood products and investigating any transfusion reactions later.


Performing a safe and effective blood transfusion requires careful coordination of multiple steps before, during and after the procedure. First, doctors must determine if it is truly clinically indicated based on the patient’s condition and risks versus benefits. The donor blood must be appropriately matched to the recipient’s blood type through typing and cross-matching to prevent hemolytic reactions.

Rigorous screening of all donated blood eliminates units that may transmit infections. Hospitals follow strict procedures for procuring, handling and confirming compatible blood components for each patient. Informed consent ensures the patient understands the risks. At the bedside, clinicians perform critical checks just prior to starting the infusion.

Administering the blood products involves carefully controlled infusion rates and close monitoring. Finally, post-transfusion testing, continued observation and comprehensive documentation complete the process. Following this meticulous protocol of safety checks and verifications before blood transfusions maximizes the chance of good patient outcomes.

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