The present invention concerns a method, a system, the use of the system and a reinforcement member for the direct detection of the presence of a cavity in a drill-hole intended for the reception of a reinforcement member. The method comprises the injection of a drill-hole with hardening grout 6, the introduction of a reinforcement member 7, 40 to introduce a pressurized medium 37 and the measurement of the change in pressure or the detection of a flow of medium, whereby the fall in pressure or the presence of a flow of medium indicates the presence of a cavity. The system comprises a container 26 comprising a pressurised medium 37, a reinforcement member 7, 40 comprising a channel 15, 41 through which the pressurised medium in the container is added to the drill-hole at the presence of a cavity, and a pressure gauge 27 or a flow meter 50, where the pressure gauge measures a change in pressure or the flow meter detects a flow of medium, whereby a fall in pressure or a flow of medium indicates the presence of a cavity. The invention is used during the construction of tunnels and mines in order to ensure the quality of rock reinforcement that has been carried out.