Instructions included with monoclonal Rh(D) typing reagents do not require routine use of an Rh control as immunoglobulin-coated red blood cells (RBCs) rarely yield falsely positive results with low protein reagents. However, the American Association of Blood Banks (AABB) Technical Manual recommends a concurrent control be performed on patients’ RBCs that type as group AB, D+. Proficiency testing surveys presented sensitized AB, D– RBCs, which resulted in a positive direct antiglobulin test and, in some samples, spontaneous agglutination in saline. One intent of the surveys was to monitor the accuracy of the reported Rh(D) type. On an initial survey, 19 of 115 (16.5%) participants reported the RBCs as D+. Of these laboratories, 63.2 percent (12/19) had used a monoclonal/ polyclonal blend anti-D reagent. On a subsequent survey, after educational material had been distributed, only five of 113 (4.4%) participants reported the Rh type as D+. Two of these five laboratories had used a monoclonal/polyclonal blend anti-D reagent. As RBCs coated with immunoglobulin may give unreliable results with Rh typing reagents, laboratories should follow the guidelines of the AABB Technical Manual. An appropriate control should be performed whenever RBCs from patients type as AB, D+. Immunohematology 2001;17:10–13.
