A surgical method utilizes an endoscope with an elongate flexible insertion member and (i) an endoscopic instrument guide having a plurality of lumens, (ii) a flexible irrigation member slidably insertable through one of the lumens and (iii) an auxiliary endoscopic surgical instrument slidably insertable through another of the lumens. The irrigation member has a distal end provided with a multiplicity of apertures spaced from one another both longitudinally and circumferentially. Upon introduction of the endoscope insertion member into a patient, the endoscopic instrument guide is moved through the biopsy channel so that a distal end of the endoscopic instrument guide emerges from the biopsy channel. The irrigating member is then slid through endoscopic instrument guide so that the distal end of the irrigation member emerges therefrom. Upon operatively connecting a proximal end of the irrigation member to a source of pressurized liquid, liquid from the source is sprayed in a substantially uniform cylindrical distribution through the apertures at the distal end of the irrigation member, thereby cleaning organic debris from a site inside the patient. A distal end portion of the auxiliary endoscopic surgical instrument is ejected from the endoscopic instrument guide and used to perform an operation on organic tissues at the cleaned site inside the patient.