Uncinate 2... The flow from the anterior sinuses can be seen traveling along the inside surface of the uncinate process through the slots. This space can be very narrow and is often a site of obstruction. By removing the uncinate, the available drainage space is increased. It is also necessary to remove the uncinate to be able to access the ethmoid sinuses and the maxillary sinus opening with endoscopic instruments. 1999 Peter Casano, M.D.