I recently was performing a second ABO/RH confirmation on a donor that turned out to be a different blood type from solid phase results. I thought I should write about this because this is the first time no questions marks have came up in the results field. The donor typed O positive on the machine. During my manual tube testing I noticed a mixed field in the forward typing of the A. This mixed field may have been missed very easily since I thought the donor was O positive. O positive donors only receive O positive blood so no mixed field.
After checking the patient history, it turns out the patient has a Anti-A1. The patient has typed as A positive many times at this hospital blood bank. The patient received 2 units of O positive packed cells 2 weeks before. This explained why there was a mixed field and the reverse A typed as a 2 plus. The patient received plasma later on in the evening. Luckily it was A plasma instead of O plasma.