An adapter for coupling with a medical coupling unit and a medical sensor that are configured for being coupled for electrical signal transmission between them, wherein the medical sensor comprises an ECG lead set, said adapter comprising: - an adapter coupling unit comprising - a coupling-side connector configured to fit with a coupling-side connector of the medical coupling unit and including a plurality of coupling-side electrical contacts (111, 113) for contacting a plurality of electrical contacts (11, 13) of the coupling-side connector of the medical coupling unit and - a sensor-side connector configured to fit with a sensor-side connector of the medical sensor and including a plurality of sensor-side electrical contacts (121, 123) for contacting a plurality of electrical contacts (21, 23) of the sensor-side connector of the medical sensor, allowing the adapter coupling unit to be mechanically coupled between the medical coupling unit and the medical sensor, wherein the coupling-side connector and the sensor-side connector are mechanically configured complementary to each other allowing a coupling of the medical coupling unit and the medical sensor either directly or via the adapter, - one or more wires fixedly connected to the adapter coupling unit for coupling one or more sensor elements with the adapter coupling unit for electrical signal transmission from the one or more sensor elements to the adapter coupling unit, and - connection circuitry within the adapter coupling unit for connecting each of said sensor-side electrical contacts (121, 123) and each of said one or more wires with a respective different contact of said coupling-side electrical contacts (111, 113) allowing signal transmission of electrical signals measured by the medical sensor and one or more sensor elements coupled to the adapter coupling unit to the medical coupling unit, wherein a first end of each of the one or more wires is connected, within the adapter coupling unit, to the connection circuitry and a second end of each of the one or more wires is arranged outside of the adapter coupling unit, and characterised in that the adapter coupling unit is constructed either i) to form the coupling-side connector as plug protruding from a surface of a housing of the adapter coupling unit and to form the sensor-side connector as socket recessed into another surface of the housing of the adapter coupling unit or ii) to form the coupling-side connector as socket recessed into a surface of the housing of the adapter coupling unit and to form the sensor-side connector as plug protruding from another surface of the housing of the adapter coupling unit. - an adapter coupling unit comprising - a coupling-side connector configured to fit with a coupling-side connector of the medical coupling unit and including a plurality of coupling-side electrical contacts (111, 113) for contacting a plurality of electrical contacts (11, 13) of the coupling-side connector of the medical coupling unit and - a sensor-side connector configured to fit with a sensor-side connector of the medical sensor and including a plurality of sensor-side electrical contacts (121, 123) for contacting a plurality of electrical contacts (21, 23) of the sensor-side connector of the medical sensor, allowing the adapter coupling unit to be mechanically coupled between the medical coupling unit and the medical sensor, wherein the coupling-side connector and the sensor-side connector are mechanically configured complementary to each other allowing a coupling of the medical coupling unit and the medical sensor either directly or via the adapter, - a coupling-side connector configured to fit with a coupling-side connector of the medical coupling unit and including a plurality of coupling-side electrical contacts (111, 113) for contacting a plurality of electrical contacts (11, 13) of the coupling-side connector of the medical coupling unit and - a sensor-side connector configured to fit with a sensor-side connector of the medical sensor and including a plurality of sensor-side electrical contacts (121, 123) for contacting a plurality of electrical contacts (21, 23) of the sensor-side connector of the medical sensor, - one or more wires fixedly connected to the adapter coupling unit for coupling one or more sensor elements with the adapter coupling unit for electrical signal transmission from the one or more sensor elements to the adapter coupling unit, and - connection circuitry within the adapter coupling unit for connecting each of said sensor-side electrical contacts (121, 123) and each of said one or more wires with a respective different contact of said coupling-side electrical contacts (111, 113) allowing signal transmission of electrical signals measured by the medical sensor and one or more sensor elements coupled to the adapter coupling unit to the medical coupling unit,