Demand v need v physician prerogatives in the use of the WBC differential.

The clinical use of the WBC differential was investigated before and after it was made available on demand. The results indicate that no consistent policy existed in our hospital for the ordering of a differential. When differentials were made available on demand, the number of differentials did not increase compared with earlier periods. The demand for differentials may have been caused more by the denial of a physician's prerogative to order a differential rather than by its requirement for patient care.