Case B6: ABO Group Inconsistent with Records

Learning Outcomes

Upon completion of this exercise, participants should be able to:

  1. Discuss procedures used to verify patient identification when collecting pretransfusion blood specimens
  2. Discuss the importance of patient records in preventing misidentification in the transfusion service
  3. Describe a suitable investigation protocol when a patient's current blood type disagrees with the historical record
  4. List the places that patient misidentification can occur prior to transfusion
  5. Explain precautions related to the use of records

Case Report

A 50-year-old female (AW) was admitted to hospital for a radical hysterectomy to treat cervical cancer.  A crossmatch for 2 units of RBC was ordered.


  • Transfusion: 2 RBC 10 years ago for postpartum hemorrhage. Patient was group A Rh positive, antibody screen negative
  • Pregnancy: two
  • Medications: occasional ibuprofen for osteoarthritis pain

Transfusion Service Results

Initial pretransfusion testing results

Based on these results:

  • a new blood sample was collected and retested STAT
  • all crossmatched inventory was put on temporary hold

Pretransfusion testing results (recollected specimen)

Whenever an ABO group on a current specimen does not agree with the patient's historical blood group, there are several possibilities, including:

  • Patient misidentification has occurred now or in the past (one of the specimens is not from the patient)
  • The incorrect group was entered in the records due to a clerical error
  • The patient has had a bone marrow or stem cell transplant and has changed blood groups

In this case the results on the recollected specimen determined that patient misidentification had occurred on this admission and that the initial specimen was not from patient AW.

  • A protocol was initiated to supply uncrossmatched group O Rh negative RBC for urgent transfusions to patients without historical records whose samples had been drawn by the same blood collector implicated in AW's initial specimen.

The blood collector (SH) who had drawn the first specimen had completed her shift and was off duty. She was immediately contacted at home and questioned about the collection procedure for the patient in question.

After much discussion SH said that she used computer-generated patient identification labels and admitted to pre-labelling specimen tubes for two patients on her last collection trip of the day because she was in a rush to finish her shift. She insisted that she had checked patient arm bands for all collections as that was her normal procedure.

Follow-Up and Case Outcome

  • Every patient whose crossmatch sample was drawn by the collector on her last collection run was recollected and tested. Of five patients, one (OP, who was in the same room as AW) showed a blood group discrepancy. OP (a patient with no record of prior testing) had initially tested as group A Rh positive and 3 units of RBC had been successfully crossmatched. However, OP now typed as group O Rh positive.
  • These results suggested that the collector had switched blood samples and drawn AW's  (group A blood) into the specimen tube labelled for OP (who was really group O) and vice versa.
  • OP was re-crossmatched with group O Rh positive RBC.
  • Crossmatched inventory was taken off hold and made available for issue.


See the case discussion, including interactive questions with feedback.

Final Quiz

This quiz is offered as a self assessment.

  1. At which two stages do most identification errors occur prior to transfusion?
  2. With regard to using a patient's records for blood transfusion, provide an example when it is
    • clearly acceptable to do so for the patient's safety
    • clearly unacceptable to do so for the patient's safety
    • open to the judgement of individual transfusion services
  3. When collecting a blood specimen for pretransfusion testing, which of the following procedures conform to acceptable practice?
    1. The identity of the person drawing the blood sample must be documented.
    2. Blood specimens can be prelabelled before entering the patient's room providing the patient has an identification band.
    3. If there is a discrepancy between patient identity on the identification band and the requisition, the specimen can be collected and the discrepancy resolved later.
    4. The date and time of specimen collection must be documented.
    5. When a patient's current blood group and historical blood group do not coincide, a new specimen should be collected and tested immediately.
    6. If the patient is semi-conscious and cannot spell his or her first and last name,  a responsible adult such as a relative, nurse or physician may identify the patient.
  4. Whenever a discrepancy is found between a patient's current blood grouping results and historical record, why is it good practice to hold previously crosssmatched blood for all patients until the discrepancy is resolved or, alternatively, to issue group O Rh negative RBC if transfusions are urgently required?
  5. Why is correct patient identity crucial for pretransfusion testing?

Further Reading

CBBS e-Network Forum: Compatibility testing for issuing non-rbc components

Callum, JL, Kaplan, HS, Merkley, L L, Pinkerton, PH, Rabin Fastman, B, Romans, RA.  Reporting of near-miss events for transfusion medicine: improving transfusion safety. Transfusion 2001; 41: 1204-11. [ Medline ]

Contreras M, de Silva M. Preventing incompatible transfusions. Br Med J 1994; 308(6938): 1180-1. [ full text ]

Linden JV, Wagner K, Voytovich AE, Sheehan J. Transfusion errors in New York State: an analysis of 10 years' experience. Transfusion 2000;40(10):1207-13. [ Medline ]

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 ]

McClelland DBL, Phillips P. Errors in blood transfusion in Britain: survey of hospital haematology departments. Br Med J 1994;308:1205-6. [Full Text]

Mercuriali F, Inghilleri G, Colotti MT, Fare M, Biffi E, Vinci A, Podico M, Scalamogna R. Bedside transfusion errors: analysis of 2 years' use of a system to monitor and prevent transfusion errors.Vox Sang 1996;70(1):16-20. [ 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 ]