Question: What is the most accurate diagnosis code for Rh-negative status during pregnancy? Arkansas Subscriber Answer: Status is status, not isoimmunization where the patient has serum evidence of antibodies. For status, use Z31.82 (Encounter for Rh incompatibility status) if the visit is for this reason. If you are simply trying to report that she is Rh-negative, go to the Z67.- (Blood type) code category. Suzanne Burmeister, BA, MPhil, Medical Writer and Editor