A stepbystep overview of a patent application and maintenance process. The five stages of a patent process.This tutorial will focus on patents and the process for securing a patent in the U.S. First, let's consider why we have a patent system? • Provides a lowercost first patent filing in the United States. A flow reversal (or a hepatofugal flow) is seen in the case of portal hypertension (Fig. 6). In the other eight dogs the patent shunt was non-functional, because a hepatopetal flow was detected in the shunt adjacent to the portal vein.