The invention relates to a device that includes: a gas insufflation device (1), a first duct (2) for supplying gas to a member (3) that can be inserted in a cavity of an individual, wherein the first duct (2) includes a by-pass (21) for discharging excess gas to the outside. The insertable member (3) has three channels and includes a first opening(31) on the rear end thereof for connecting the first duct (2) to a channel (32) having an outlet opening (33), a second opening (34) for connecting an effluent discharge duct (5) to a channel (35) having an inlet opening (36) and a third opening (37) for connecting an inflation means (6) for an expandable annular element (30) provided with a channel (38) having an outlet opening (39) to the expandable annular element (30)located in front of the openings (33, 36).
