This section will review the role played by patient blood group records in pretransfusion testing, including their importance in preventing misidentification and precautions related to their use. The discussion is not meant to be definitive or all inclusive.

Importance of Identification to Transfusion

Before considering patient records, the importance of correct patient identification will be briefly reviewed. The most common cause of acute hemolytic transfusion reactions is patient misidentification. Such errors can lead to patients being transfused with donor blood of the wrong ABO group, resulting in severe hemolysis.

The stages where identification errors may occur include:

  • drawing the patient's pretransfusion specimen
  • labelling the patient's blood specimen, which must be done in the patient's presence
  • performing pretransfusion testing in the transfusion service
  • issuing donor blood from the transfusion service
  • identifying patient and donor unit immediately prior to transfusion

Most identification errors occur when collecting the patient's sample and when identifying the patient/donor unit prior to transfusion.

Role of Patient Records

Whenever a pretransfusion specimen and requisition arrive in the transfusion service (TS), a history check is always done on the patient. Past records can be invaluable in several ways.

Preventing transfusion of incompatible blood due to patient misidentification

This is one of the major uses of past records. See, for example, Case B6.(ABO group inconsistent with records).

Preventing transfusion of incompatible blood due to weak antibodies

Records can protect the patient who has a weak, undetectable antibody. Even when an antibody is detectable, records can save the transfusion service time in obtaining antigen-negative donor red cells.

Identifying special transfusion requirements

Records increase transfusion safety by providing information about special transfusion requirements, e.g., theneed for CMV-negative, irradiated, or washed blood components.

Identifying previous testing problems

Records provide access to information about previous testing problems such asABO and Rh typing discrepancies and associated investigation and resolution, patients with positive direct antiglobulin tests (DATs) that remain positive over time

Tracking transfusion-associated transmissible diseases

Patient records play a crucial role in tracking transfusion-associated transmissible diseases by facilitating tracebacks and lookbacks.

Precautions and Limitations of Patient Records

Although records play a critical role in the transfusion service, there are significant precautions associated with their use. Sometimes records may be relied upon without confirmation, e.g., if a patient has a record of having a clinically significant antibody but the antibody can no longer be detected, antigen-negative donor units would be crossmatched. In this case there is a logical explanation for the discrepancy and trusting the record protects the patient.

However, **most blood requests require current testing**. In particular:

RBC. Historical ABO blood groups are NEVER used to issue RBC. Misidentification and clerical errors occur fairly commonly and can result in life-threatening hemolytic transfusion reactions.1,2

1. Williamson LM, Lowe S, Love EM, Cohen H, Soldan K, McClelland DB, et al. Serious hazards of transfusion (SHOT) initiative: analysis of the first two annual reports. Br Med J 1999;319:16-9. [ full text ]

2. 2003 SHOT Report

ABO and Rh records on cards carried by patients are NEVER used for transfusion purposes since they are totally unreliable.Cases exist anecdotally and in the literature of records being wrong.Examples (based on personal experience of author):

  • A patient presented to her physician under a false identity (her girlfriend's) and was admitted to hospital for a therapeutic abortion under that identity; her ABO group disagreed with the record since her friend had been previously crossmatched.
  • A patient was crossmatched due to a motorcycle accident and his ABO group did not agree with his record; patient was carrying an identity card of his older friend for the purpose of buying liquor in a bar, and the friend had been previously crossmatched.
  • A patient's ABO group disagreed with her record based on testing two days ago; staff questioned why a new type and screen was ordered when a current valid sample existed but did the group anyway. Investigation revealed that an interning health professional was curious about his blood group and convinced a collector to take his sample under the identity of an existing patient.

Platelets and Plasma. Using historical blood groups for issuing platelets and plasma is not so clear. For example, once typed, do patients require ABO and Rh typing on each admission? Because there are no standards that address this issue, policies are set by individual transfusion services.

See discussion on the CBBS e-Network Forum: Compatibility testing for issuing non-rbc components(Dec. 13, 2000).

An advantage of typing each admission is that a crossmatch specimen would be readily available should RBC transfusion be required.

Standards and Regulations

Standards and regulations exist for using historical blood groups for RBC requests and specifically prohibit it. For example:

CSTM Standards (Canada). Regarding emergency transfusions: Clause G9.2.4 (verbatim). When time permits, the ABO and Rh group of the recipient shall be determined, and blood products of an appropriate group issued. Previous records shall not be used to obtain the recipient's ABO and Rh group for red cell requests.

CSA Standard Z902-04. Regarding emergency transfusion: Clause (paraphrased) specifies that ABO group-compatible red blood cells may be transfused prior to completing compatibility tests if the recipient?s ABO group has been determined without relying on previous records.

This Case

In this case, the technologists on duty - without consulting an onsite physician or the central transfusion facility - issued 3 group A Rh positive RBC for JS based solely on his past records. By so doing they broke best practice standards and endangered the patient's life. A severe hemolytic transfusion reaction ensued resulting in his death.

JS was tested on 2 separate current blood samples and found to be group O Rh positive. It's probable that misidentification occurred 5 years ago when he was tested and recorded as group A Rh positive, fortunately receiving no transfusions with group A red cells at the time.It's also possible that a second error happened concurrently and that there is a patient documented as group O Rh positive who is actually A Rh positive.

Learning Points

  • Records of patient blood groups are invaluable in helping to prevent misidentification and serve to increase transfusion safety in other ways.
  • However, historical blood groups must NEVER be used for RBC transfusion requests, because, if the records are wrong, ABO-incompatible RBC may be transfused that threaten the patient's life.
  • Misidentification errors are common causes of severe transfusion-associated adverse events.

Practical Notes

  • Because hemovigilance systems such as SHOT have revealed misidentification errors as common causes of severe transfusion reactions, preventing misidentification should be a significant focus of TS resource allocation.
  • Several technological tools have been promoted to eliminate identification errors.

*If you have comments on this section, please contact Pat: This email address is being protected from spambots. You need JavaScript enabled to view it.

TraQ self study questions

1. Where can patient misidentification occur?


2. What are some of the benefits of patient records when pretransfusion testing?


3. What are some of the precautions related to using records in the TS?


4. Why cannot records be used to obtain the recipient's ABO and Rh group for RBC transfusion?


More Discussion...

  • Part 1: Use of historical blood groups <--You are here
  • Part 2. Issuing blood to the OR
  • Part 3. Medical consultation
  • Part 4: Transfusion-related responsibilities
  • Part 5: Training and competency assessment

Further Reading


Lumadue, JA, JS Boyd, and PM Ness. Adherence to a strict specimen-labeling policy decreases the incidence of erroneous blood grouping of blood bank specimens. Transfusion. 1997;37:1169?72. [Medline]

Williamson LM, Lowe S, Love EM, Cohen H, Soldan K, McClelland DB, et al. Serious hazards of transfusion (SHOT) initiative: analysis of the first two annual reports. Br Med J 1999;319:16-9. [ full text ]

Online resources

CBBS e-Network Forum: Compatibility testing for issuing non-rbc components(Dec. 13, 2000).

2003 SHOT Report

TraQ clearinghouse: Technology to enhance safety