Evaluation of the gel test for antibody screening in a tertiary hospital in Hong Kong; insensitivity for some cold antibodies that are reactive at 37 degrees C by conventional indirect antiglobulin tests.

The antiglobulin gel test (DiaMed) was compared with conventional IAT methods in pretransfusion antibody screening in a tertiary hospital in Hong Kong. Antibody titrations showed that the gel system was more sensitive than the tube IAT method in detecting anti-D, anti-S, anti-s, but slightly less sensitive with anti-E. The gel tests detected all clinically significant warm reacting allo-antibodies detected by conventional IAT methods except one case of weak anti-E. It detected a case of anti-C missed in conventional screening. The number of serological investigations due to false positive screens, non-specific antibodies and clinically insignificant cold antibodies (anti-P, and anti-Lewis) were reduced. The gel system was fast and easy to use. It would reduce delays and inconvenience caused to patients due to false positive screens and non-specific antibodies without compromising detection of clinically significant antibodies. However, of concern was the failure to detect several cases of anti-Le(a) and anti-P1 that were reactive at 37 degrees C by conventional IAT and one case of anti-H in a patient with Parabombay A.