HEPAR: an expert system for the diagnosis of disorders of the liver and biliary tract.

The HEPAR system is a medical expert system intended as a supportive tool for the diagnosis of disorders of the liver and biliary tract. In the system, the role of information from the medical interview, physical examination, and simple non-invasive diagnostic methods, such as ultrasonography, is emphasized in order to reduce the number of diagnostic procedures to be applied. Medical diagnosis is modelled in the system using the formalism of if-then rules. Based on patient data available, the system determines whether the data indicate a hepatocellular or a biliary obstructive disorder, and whether or not benign or malignant features are present. Moreover, the system produces a subset of possible diagnoses out of a set of more than 70 diagnostic categories. The system is still under development. In a preliminary study, the HEPAR system has been evaluated using data from 94 jaundiced patients. Conclusions with respect to the hepatocellular or biliary obstructive nature of the disorder, the benign or malignant nature of the disorder, and the final diagnosis, were reached in 95%, 65%, and 80% of the cases, respectively. These conclusions were correct in 85%, 92%, and 80% of the classified cases, respectively. The system was shown not to be sensitive to incompleteness of information.