An endoscopic shaft assembly, comprising: an elongate outer shaft; an inner shaft; and an outer housing coupled to a proximal portion of the elongate outer shaft, the outer housing including: a tubular wall defining a cavity; a biasing member disposed within the cavity; and a shaft plunger disposed within the cavity and fixedly coupled to the proximal end of the inner shaft, wherein the shaft plunger is configured to move axially within at least a portion of the cavity along a travel path from a first position to a second position, the shaft plunger including a collar, characterised in that the collar is configured to be separated from the tubular wall along a first travel portion of the travel path and to contact the tubular wall along a second travel portion of the travel path, whereby the biasing member is arranged to move the shaft plunger upon detaching the endoscopic shaft assembly from the handle assembly into the first position in which the collar is separated from the tubular wall; and the plunger and tubular wall are configured so that the separation of the collar from the tubular wall opens up a passage into the outer housing and endoscopic shaft assembly which allows for the introduction of a sterilization agent into the endoscopic shaft assembly. an elongate outer shaft; an inner shaft; and an outer housing coupled to a proximal portion of the elongate outer shaft, the outer housing including: a tubular wall defining a cavity; a biasing member disposed within the cavity; and a shaft plunger disposed within the cavity and fixedly coupled to the proximal end of the inner shaft, wherein the shaft plunger is configured to move axially within at least a portion of the cavity along a travel path from a first position to a second position, the shaft plunger including a collar, characterised in that the collar is configured to be separated from the tubular wall along a first travel portion of the travel path and to contact the tubular wall along a second travel portion of the travel path, whereby the biasing member is arranged to move the shaft plunger upon detaching the endoscopic shaft assembly from the handle assembly into the first position in which the collar is separated from the tubular wall; and the plunger and tubular wall are configured so that the separation of the collar from the tubular wall opens up a passage into the outer housing and endoscopic shaft assembly which allows for the introduction of a sterilization agent into the endoscopic shaft assembly. a tubular wall defining a cavity; a biasing member disposed within the cavity; and a shaft plunger disposed within the cavity and fixedly coupled to the proximal end of the inner shaft, wherein the shaft plunger is configured to move axially within at least a portion of the cavity along a travel path from a first position to a second position, the shaft plunger including a collar, characterised in that the collar is configured to be separated from the tubular wall along a first travel portion of the travel path and to contact the tubular wall along a second travel portion of the travel path, whereby the biasing member is arranged to move the shaft plunger upon detaching the endoscopic shaft assembly from the handle assembly into the first position in which the collar is separated from the tubular wall; and the plunger and tubular wall are configured so that the separation of the collar from the tubular wall opens up a passage into the outer housing and endoscopic shaft assembly which allows for the introduction of a sterilization agent into the endoscopic shaft assembly.