An adapter (1) for cleaning a medical appliance comprises a fluid channel (2) with an inlet (3) and at least one outlet (4.1), at least one outlet being provided with a coupling unit (5.1) for an opening of a medical device. The coupling unit (5.1) is designed as a single-use coupling which, after the medical device has been coupled for the first time, generates a leak in the fluid channel at the time of uncoupling. This ensures totally hygienic cleaning of medical devices.