789.51 is a legacy non-billable code used to specify a medical diagnosis of malignant ascites. This code was replaced on September 30, 2015 by its ICD-10 equivalent.
References found for the code 789.51 in the Index of Diseases and Injuries:
General Equivalence Map Definitions The ICD-9 and ICD-10 GEMs are used to facilitate linking between the diagnosis codes in ICD-9-CM and the new ICD-10-CM code set. The GEMs are the raw material from which providers, health information vendors and payers can derive specific applied mappings to meet their needs.