An endoscopic device comprises a tubular endoscopic sheath which has distal and proximal ends and is receivable in a patient, a telescope portion in the sheath, and an irrigation and drainage valve mounted on the device adjacent the proximal end of the sheath. The telescope portion is operable for viewing...http://www.google.es/patents/US4567880?utm_source=gb-gplus-sharePatente US4567880 - Endoscopic device with three-way valve
