Comparative Analysis of Clinical Samples Showing Weak Serum Reaction on AutoVue System Causing ABO Blood Typing Discrepancies

BACKGROUND: ABO blood typing in pre-transfusion testing is a major component of the high workload in blood banks that therefore requires automation. We often experienced discrepant results from an automated system, especially weak serum reactions. We evaluated the discrepant results by the reference manual method to confirm ABO blood typing. METHODS: In total, 13,113 blood samples were tested with the AutoVue system; all samples were run in parallel with the reference manual method according to the laboratory protocol. RESULTS: The AutoVue system confirmed ABO blood typing of 12,816 samples (97.7%), and these results were concordant with those of the manual method. The remaining 297 samples (2.3%) showed discrepant results in the AutoVue system and were confirmed by the manual method. The discrepant results involved weak serum reactions (<2+ reaction grade), extra serum reactions, samples from patients who had received stem cell transplants, ABO subgroups, and specific system error messages. Among the 98 samples showing ≤1+ reaction grade in the AutoVue system, 70 samples (71.4%) showed a normal serum reaction (≥2+ reaction grade) with the manual method, and 28 samples (28.6%) showed weak serum reaction in both methods. CONCLUSIONS: ABO blood tying of 97.7% samples could be confirmed by the AutoVue system and a small proportion (2.3%) needed to be re-evaluated by the manual method. Samples with a 2+ reaction grade in serum typing do not need to be evaluated manually, while those with ≤1+ reaction grade do.

Evaluation of Two Automated Instruments for Pre-transfusion Testing: AutoVue Innova and Techno TwinStation / 대한진단검사의학회지

BACKGROUND: Despite the advances in total laboratory automation, a considerable amount of work in blood banks is still done using outdated manual methods. Some automated pre-transfusion testing instruments have recently been developed. Of these, we evaluated and compared the AutoVue Innova (Ortho, USA) and the Techno TwinStation (DiaMed AG, Switzerland). METHODS: Forward and reverse ABO/Rh typing and unexpected antibody screening and identification tests were performed on 4,628 samples using the manual method and the two automated instruments. Two different anticoagulants (EDTA and citrate) were compared in ABO/Rh typing and unexpected antibody screening tests. Titrating studies were conducted on the following 7 dilutions using 5 samples of irregular antibodies with anti-E, anti-E & -c, anti-D, and anti-Le(a) with anti-Fy(a): 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, and 1:128. The test throughput per hour, the time required to perform 1 and 100 tests, and a simulation test for total events occurring in 1 day were also measured. RESULTS: No erroneous results were reported between the two instruments and the manual method. Discrepancies observed in 10 cases (0.4%) of ABO/Rh typing were of higher intensity with AutoVue Innova than with the manual method. AutoVue Innova exhibited the highest sensitivity in the titrating study and throughput performance compared with the manual method and the Techno TwinStation. Especially in the throughput and time required to complete 100 antibody screening tests, AutoVue Innova had a 3.3- and 3.5-fold higher performance, respectively, than Techno TwinStation. CONCLUSIONS: Because both of the two fully automated instruments (AutoVue Innova and Techno TwinStation) had high levels of accuracy and performance, it is expected that use of fully automated instruments will reduce human labor, turnaround time, and operator error in the blood bank.

Use of the gel-based DiaMed-ID microtyping system for crossmatching enhances sensitivity.

A host of newer techniques have been introduced over the past decade in blood bank serological testing. One such technology which has been in vogue in the west since early 1990s is the gel test. The procedures used are standardized and they provide clear and stable reactions that improve result interpretation. The principle involves the differential passage of red cell agglutinates and free red blood cells through a dextran acrylamide gel. The results are stable and may be read even after many hours. The test is easy to perform, sensitive and reproducible. We report our experience in compatibility testing with use of the DiaMed micro typing system which is based on the gel technology. Over a one year period since this technology was introduced in our blood bank, we noticed a startling 65 fold rise (p<0.0001) in the reported number of incompatible units in one year which rose from a paltry 4 (0.02%) to 260 (1.6%). We found the DiaMed system easy to use and as our findings suggest it proved to be more sensitive than the conventional tube agglutination technique.