A new concept optionally embedded in the Extended IPU that becomes active if interferences in the measurement of red blood cells or related parameters (e.g. MCHC) are detected. This refers, for example, to cold agglutination, haemolysis or hypo-osmolarity. The algorithm delivers conclusive information about the cause of interference, suggests the replacement of the affected parameters with their counterparts from the RET analysis and automatically recalculates the RBC indices. In doing so, CBC-O relieves the laboratory by automating the workflow for certain problematic samples.