A medical device for detecting a leakage of fluid on a subject includes a support, configured for being secured on the subject, and an optical sensor on the support. The support defines, in a region between the optical sensor and a lower face thereof, a detection surface that can be reached by leakage fluid. The optical sensor is arranged for detecting a leakage of fluid. The optical sensor has a sensor body with an emitter and a receiver of electromagnetic radiation. The support and the sensor body have mutual-coupling means, for retaining the sensor body on the support in such a way that a presence of leakage fluid can be detected via the optical sensor.