A system for insertion of a sterile probe into a sterile vessel wherein said system comprises: (i) a body formed of plastic and having a sterile bore formed through at least a portion of its interior, the body having a first and second end, the second end comprising a body sterile face connection; (ii) a plunger formed of plastic and contained within the sterile bore of the body, the plunger having a shape substantially corresponding to that of said sterile bore and being of a diameter less than said sterile bore, the plunger also having an inner channel opening onto a first aperture on a first end of said plunger and a second aperture on a second end of said plunger, wherein said first and second ends of said plunger correspond respectively to said first and second ends of said body, and wherein said plunger is moveable between a first position and a second position; (iii) a sterile probe secured within the inner channel of said plunger wherein said sterile probe comprises an electrical connection end substantially aligned with said first end of said plunger, a sensor end substantially aligned with said second end of said plunger, and a sensor body therebetween; (iv) one or more seals (40, 41, 42) between the plunger and the sterile bore to form a liquid-tight seal between various portions of the plunger and the sterile bore; and, (v) a handle cooperating with said plunger to direct movement of said plunger within the sterile bore between said first position and said second position, the system being characterised in that said body further comprises a sterilization port allowing the penetration of sterilizing gas, into the sterile bore. (i) a body formed of plastic and having a sterile bore formed through at least a portion of its interior, the body having a first and second end, the second end comprising a body sterile face connection; (ii) a plunger formed of plastic and contained within the sterile bore of the body, the plunger having a shape substantially corresponding to that of said sterile bore and being of a diameter less than said sterile bore, the plunger also having an inner channel opening onto a first aperture on a first end of said plunger and a second aperture on a second end of said plunger, wherein said first and second ends of said plunger correspond respectively to said first and second ends of said body, and wherein said plunger is moveable between a first position and a second position; (iii) a sterile probe secured within the inner channel of said plunger wherein said sterile probe comprises an electrical connection end substantially aligned with said first end of said plunger, a sensor end substantially aligned with said second end of said plunger, and a sensor body therebetween; (iv) one or more seals (40, 41, 42) between the plunger and the sterile bore to form a liquid-tight seal between various portions of the plunger and the sterile bore; and, (v) a handle cooperating with said plunger to direct movement of said plunger within the sterile bore between said first position and said second position, the system being characterised in that said body further comprises a sterilization port allowing the penetration of sterilizing gas, into the sterile bore.