Also known as “electronic crossmatch,” this is a type of major crossmatch done without the need for test tubes or contact between donor red cells and patient serum. The blood bank computer system compares ABO and Rh types of the donor and recipient for compatibility. Note that computer crossmatches can only be used when the recipient has been tested on more than one occasion and when a computer system is used that is approved by FDA for this purpose and validated on site. In addition, you cannot use computer crossmatches under the following circumstances: 1) If the recipient or donor has a clinically significant antibody; or 2) If the recipient has an ABO discrepancy. In those settings, a serologic crossmatch must be done instead. Computer crossmatches can be done rapidly, and they are considered as safe as the immediate spin crossmatch when done under the conditions outlined above (you should note that patients eligible for the immediate spin crossmatch are the same as those eligible for the computer crossmatch).