I searched the forum and read some discrepancy info from back in 2013 and 2014 but most of those patients had history of transfusion. Two days ago we had a prenatal T&S. No blood transfusions involved. We had no previous history of type or transfusions on file. The sample was tested on the ECHO and clearly typed as D negative with no discrepancies or concerns with both Anti-D reagents. Patient was reported as D negative. The same day we receive a call from the patient's midwife stating the patient has a history of being B Positive. We pulled the original sample and repeated testing on the ECHO. The repeat testing resulted in ? with at least one of the Anti-D reagents and resulted as NTD. (No type determined). We proceeded to perform tube as well as ECHO weak D testing. Patient was 2+ positive in tube with AHG phase using the exact same reagents used on the ECHO and 4+ positive with both Anti- D reagents ECHO weak D. My question is why did the initial test not react? If this was a particular variant etc., I could chalk it down to method or reagent but having one result on the same sample tested on the same day and then finding another result hours later when repeated does leave me wondering. Any ideas?? I will say the sample was EDTA and was refrigerated for several hours prior to the repeat testing.