Blood Groups and Matching: Under What Conditions Is Blood Transfusion Done & the Needed Precautions

Blood is one of the vital elements of the human body that carries oxygen to the different parts of the body, produces antigens and immunity boosters in the body and facilitates the working of all the organs. In this article, we look at types of blood groups and matching and understand under what conditions blood transfusion is done. Here, we also discuss the precautions that should be taken before blood transfusion.

Blood Groups

When we talk about blood groups we are discussing the different classifications of blood that is done based on the antibodies and the different antigenic bodies that are inherited from the parents and the families. These elements are present on the surface layers of red blood cells (RBCs) or in the human blood. These antigens mainly comprise carbohydrates, proteins, glycolipids or glycoproteins, which again varies in different blood groups. Blood types are always inherited from parents and mark a contribution from both the parents.

Researches done in the domain has marked the existence of nearly 36 different blood group systems with a presence of nearly 346 antigens. Out of the 36 blood group systems, the Rh factor and the ABO blood groups are the most important. These combined systems denote the blood group type of a person such as A, B, O, and AB. The Rh factor denotes whether the D protein is present, or absent. These are the aspects that happen to be so very important for blood transfusion and have to be checked compulsorily before transfusion of blood. Blood Groups and Matching

Blood Groups and Matching

At the time of blood transfusion, the group of blood is always determined. This is important since if a mismatched blood group is transfused in a body it can lead to clumping of the blood cells intravenously that can also be fatal. To explain it further it can be said that a blood group A has naturally occurring anti B antibodies. So when a person with a blood group A is given a blood transfusion from a blood group B person then the given B blood group cells can clump intravenously that can be deadly for the person receiving the blood transfusion. The same can be said about any other form of mismatched blood transfusion. At the time of blood transfusion, the RhD factor that denotes the positive (+) and the negative (-) must be borne in mind. A person who is having a positive (+) blood group can receive blood from both the RhD sections of the matching ABO factor. However, a person with a negative (-) blood group has to get a blood transfusion from a negative blood group. People with a blood group O can donate their blood to people with blood groups A, B, and AB. This is because people with a blood group O do not have antibodies for both A and B groups of blood. Blood groups and matching the groups before blood transfusion is called blood group compatibility testing. The matching is necessary to avoid incompatibility between the blood groups of the recipient and the donor. Hence they should be checked for their blood groups and their compatibility or matching must be confirmed.

Under What Conditions Is Blood Transfusion Done?

Blood transfusion is the process through which a person who has lost a good amount of blood or a person for whom certain parts of the blood have been depleted is given blood from an external source. Simply put when a person is given blood from outside, the process is known as a blood transfusion. It is important to understand the conditions in which blood transfusion is done. Patients of various orders and categories suffering from different physical conditions often require a blood transfusion. This is one of the most common procedures that are conducted in millions of cases across the various parts of the world. Studies have shown that the commonest clinical indications of blood transfusion include cases of anemia, hemorrhage, critical illness, surgeries or sepsis.1 Experts have also given the guidelines for the use of blood transfusion, which clearly states the situations where blood transfusion needs to be done.

These guidelines are followed by health professionals to confirm under what conditions blood transfusion is done. It lists the criteria for various categories of patients. On an average, post-operative patients and patients with cardiac with hemoglobin less than 8g/dl may be considered for blood transfusion, while patients in the intensive care unit level less than 7g/dl must be treated immediately. Similarly, for patients with traumatic brain injury and any other conditions, the hemoglobin levels must be maintained above 9g/dl. The decision of whether blood transfusion needs to be done must be taken after considering all other parameters as well. Here is a detailed list of the conditions where blood transfusion is done.

Surgery as a Major Factor for Blood Transfusion: This is one of the most common conditions where blood transfusion is needed. A critical surgery or the one that continues for long often requires an external blood supply to the patient or blood transfusion. One of the most common types of such surgeries includes those of heart or cardiac operations.

Serious Injuries: People who are suffering from serious injuries that can occur due to serious accidents, soldiers and people returning from war situations, car or vehicle crashes or even natural disasters experience a very severe blood loss. These are the people who require a good amount of blood transfusion in most of the cases.

Severe Ailments: There are several ailments where the body is no longer able to make the required amount of blood. This is common in people with certain liver disorders or blood disorders. This is when you can need a blood transfusion. Additionally, diseases that cause anemia that can get triggered by diseases of the kidney or cancer can also lead to loss of RBC. There are many medicines and other medical treatment procedures like radiation that can also be linked to anemia and thalassemia. These are the conditions when blood transfusion is required.

Bleeding Disorders as Another Condition Where Blood Transfusion is Required: There are many bleeding disorders such as thrombocytopenia and hemophilia that can also lead to major blood loss. These are the conditions where blood transfusion is done.

What Precautions Should Be Taken Before Blood Transfusion?

Blood transfusion is a serious affair. Improper precaution at this stage can lead to several other and bigger problems and criticalities in the future. Hence at the time of a blood transfusion, certain precautions must be taken such as:

Detailed History of the Donor: The person who has come up as the donor must be made to fill up a detailed for that will ask about the medical history of the donor. The person’s hemoglobin needs to be checked and a history of any severe ailment in the past must be evaluated.

Check For HIV or Hepatitis: The acquired blood needs to be tested for blood-related diseases, mainly infections like HIV or hepatitis. This is mandatory before blood transfusion for any condition and under any circumstance.

Match Blood Groups before Blood Transfusions: The blood groups has to be matched in terms of the ABO blood group systems and also the RhD blood group systems. Only the compatible blood group can be given to the patient to avoid incompatibility and adverse effects resulting from it.

Careful Examination of the Patient: Often a close and a careful examination of the patient is done so that it can be evaluated whether the patient needs a blood transfusion or not. All the elements and the sections of the blood are tested to confirm the requirement of blood transfusion, based on which a fair decision is taken.

Close Monitoring of the Patient: Soon after the transfusion is complete the patient is often kept under a close watch to observe the vital signs like temperature, blood pressure, pulse rate, and heartbeat rate closely.


Blood transfusion is a common but critical process. A small mistake or carelessness during a transfusion can even cause the life of the patient. Blood groups and matching are the prime factors to be considered before blood transfusion. Knowing under what conditions blood transfusion is done and what precautions to be taken before blood transfusion is necessary. Blood transfusion is always considered a serious procedure and the healthcare team does it with utmost care. Hence, it is best to be aware of the details of blood transfusion and follow medical advice.