Applicator for injecting a bulking agent at one or more selected submucosal positions in a periurethral tissue of a female patients' urethra. The applicator comprises a lance, such as a cystoscope with a distal end provided with one or more optical sensors, and a needle guide with a bore receiving the lance. The needle guide comprises needle channels at different angular positions, each needle channel extending between a needle entrance surface and an opposite shoulder surface. The needle channels are oriented to direct a needle via external peripheral tissue of the urethral meatus to a submucosal position at a urethra section, e.g., within the optical scope of the optical sensor.