Blood transfusion can save lives, particularly in emergencies involving severe blood loss, childbirth complications, surgery and serious illnesses.
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However, when donated blood is not properly screened and tested for compatibility, a procedure intended to save a patient’s life can expose them to potentially fatal complications.
While determining a donor’s blood group is an essential first step, medical laboratory scientists say it is not enough to establish whether the blood is safe for a recipient.
Adedoye David and Olaiya Oluwatoba, who are medical laboratory scientists, explained to PT HEALTH WATCH that donated blood must undergo additional laboratory tests, including crossmatching and screening for transfusion-transmissible infections, before it is released for transfusion.
According to the scientists, blood grouping establishes a person’s ABO and Rhesus (Rh) blood types, but does not independently confirm compatibility between a donor and recipient.
They explained that crossmatching involves testing donor and recipient blood samples to identify possible reactions between antigens on red blood cells and antibodies in the recipient’s blood. Such reactions can cause the destruction of red blood cells, resulting in potentially serious transfusion reactions.
The scientists also cautioned against the assumption that blood group O is automatically safe for every recipient. Although group O red blood cells are commonly used in emergencies when a patient’s blood group is unknown, some group O whole-blood donations contain high levels of anti-A and anti-B antibodies that can cause haemolysis in recipients.
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Beyond compatibility, another important aspect of blood safety is ensuring that donated blood does not carry infections that could be transmitted to patients.
Screening for infections
The scientists identified hepatitis B, hepatitis C, human immunodeficiency virus (HIV 1 and 2) and syphilis as infections that must be screened for before donated blood is released.
They explained that inadequate screening could turn hospitals and blood banks into channels for transmitting infections to patients who may already be vulnerable because of their medical conditions.
They highlighted enzyme-linked immunosorbent assay (ELISA) as a preferred screening method but noted that infections can sometimes escape detection when donors are in the window period, during which an infection is present but may not yet be detectable by a particular test.
Although ELISA is an established screening method, it does not completely eliminate this risk. Nucleic acid testing (NAT), where available, can detect some infections earlier by identifying viral genetic material.
Risks of incompatible or unsafe blood
According to the scientists, one major consequence of transfusing incompatible blood is a haemolytic transfusion reaction, which occurs when the recipient’s immune system destroys transfused red blood cells.
They identified acute and delayed haemolytic transfusion reactions as possible complications. Acute reactions may present with sudden fever, chills, low blood pressure and haemoglobinuria, while delayed reactions can develop days or weeks after transfusion.
Infections such as hepatitis B, hepatitis C, HIV and syphilis may also be transmitted through inadequately screened blood.
Although these complications can occasionally occur despite routine screening, the scientists said strict adherence to laboratory procedures and quality-control measures remains essential to reducing the risks.
Maintaining standards in blood banks
On the standards guiding blood bank operations, the scientists referred to the International Organisation for Standardisation’s ISO 15189, which outlines quality and competence requirements for medical laboratories.
They also highlighted external quality assessment, through which laboratories’ testing performance is evaluated, sometimes with the support of reference laboratories.
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Acknowledging that hospitals may experience blood shortages, the scientists maintained that scarcity should not justify abandoning essential safety procedures. They said emergency release of blood before completion of all compatibility tests must follow established protocols, with appropriate authorisation and documentation.
They further explained that medical laboratory scientists are responsible for determining blood groups, conducting compatibility tests, screening donations for infections, checking packed cell volume (PCV), monitoring expiry dates and maintaining records of blood bank activities.
The scientists urged blood donors and patients’ relatives to ask questions about blood bank procedures, including donor eligibility requirements, haemoglobin levels, health conditions and infection screening.
They said greater communication between laboratory professionals, donors and patients’ relatives would improve public understanding of blood safety and strengthen confidence in transfusion services.