Disclosed herein is a system which address the problem of multiple mappings of a source ICD code to a target ICD code by using an adaptive mechanism to automatically convert to a target ICD code with the help of accompanying data and associated rules. The mechanism is based on analysis of the ICD code description, and analysis of accompanying data to determine a set of parameters to assist in the conversion. The rules are assigned numerical values to indicate the confidence of conversion. An adaptive mechanism is also disclosed that automatically tracks user overrides to refine the rules and the indicator values over time.