An apparatus for sterilizing a surgical scoping device, the apparatus comprising: a sterilization instrument insertable through a longitudinal channel that extends along an insertion tube of a surgical scoping device, the sterilization instrument comprising: an elongate probe comprising a coaxial cable for conveying radiofrequency electromagnetic energy and/or microwave EM energy, a probe tip connected at the distal end of the coaxial cable for receiving the RF and/or microwave energy, and a gas conduit for conveying gas to the probe tip; wherein the elongate probe comprises a protective sleeve that defines a lumen through which the coaxial cable extends, and wherein the gas conduit is an annular passageway formed between an outer surface of the coaxial cable and an inner surface of the protective sleeve, wherein the coaxial cable comprises an inner conductor, an outer conductor and a dielectric material separating the inner conductor from the outer conductor, wherein the probe tip comprises a first electrode connected to the inner conductor of the coaxial cable, and a second electrode connected to the outer conductor of the coaxial cable, wherein the second electrode encloses an internal volume of the probe tip, wherein the first electrode extends longitudinally within the internal volume, wherein the probe tip further comprises an insulating cap mounted at a distal end of the coaxial cable to isolate the coaxial cable from the internal volume, wherein the gas conduit is in fluid communication with the internal volume via a flow path formed between the insulating cap and the second electrode, wherein the first electrode and second electrode are configured to receive the RF and/or microwave energy from the coaxial cable to set up an electric field in the internal volume for striking a plasma therein, wherein the probe tip includes an outlet for releasing plasma from the internal volume, wherein the insulating cap is mounted within the second electrode, wherein the second electrode is a cylinder that sits within the annular passageway of the gas conduit at its distal end, and wherein a proximal end of the second electrode is castellated to provide a plurality of longitudinal notches in the cylinder that provide the flow path to permit gas flow around the insulating cap. a sterilization instrument insertable through a longitudinal channel that extends along an insertion tube of a surgical scoping device, the sterilization instrument comprising: an elongate probe comprising a coaxial cable for conveying radiofrequency electromagnetic energy and/or microwave EM energy, a probe tip connected at the distal end of the coaxial cable for receiving the RF and/or microwave energy, and a gas conduit for conveying gas to the probe tip; an elongate probe comprising a coaxial cable for conveying radiofrequency electromagnetic energy and/or microwave EM energy, a probe tip connected at the distal end of the coaxial cable for receiving the RF and/or microwave energy, and a gas conduit for conveying gas to the probe tip; wherein the elongate probe comprises a protective sleeve that defines a lumen through which the coaxial cable extends, and wherein the gas conduit is an annular passageway formed between an outer surface of the coaxial cable and an inner surface of the protective sleeve, wherein the coaxial cable comprises an inner conductor, an outer conductor and a dielectric material separating the inner conductor from the outer conductor, wherein the probe tip comprises a first electrode connected to the inner conductor of the coaxial cable, and a second electrode connected to the outer conductor of the coaxial cable, wherein the second electrode encloses an internal volume of the probe tip, wherein the first electrode extends longitudinally within the internal volume, wherein the probe tip further comprises an insulating cap mounted at a distal end of the coaxial cable to isolate the coaxial cable from the internal volume, wherein the gas conduit is in fluid communication with the internal volume via a flow path formed between the insulating cap and the second electrode, wherein the first electrode and second electrode are configured to receive the RF and/or microwave energy from the coaxial cable to set up an electric field in the internal volume for striking a plasma therein, wherein the probe tip includes an outlet for releasing plasma from the internal volume, wherein the insulating cap is mounted within the second electrode, wherein the second electrode is a cylinder that sits within the annular passageway of the gas conduit at its distal end, and wherein a proximal end of the second electrode is castellated to provide a plurality of longitudinal notches in the cylinder that provide the flow path to permit gas flow around the insulating cap.