The subject matter of our invention is adapter for ingestion advantageously injection, instillation of active and/or contrast agent advantageously drug solution and/or diagnostic solution painlessly or by reduced pain, without leakage into the urethra or into the urethra and the bladder through the external urethral orifice without using catheter. The (6) adapter is provided with a (5) central, longitudinal, inner through hole and has a rounded off (1) tip-part to be inserted into the external urethral orifice, a (2) sealing collar and a (3) cylindrical connecting part known connectable to the (4) appropriate part of a dosing device, advantageously to the ISO 594 standard Luer Slip or Luer-Lock tip of a syringe. By the process according to the invention the (6) adapter is connected by known method to the (4) appropriate part of a dosing device containing the active and/or contrast agent, advantageously to the ISO 594 standard Luer Slip or Luer-Lock tip of a syringe, then the active and/or contrast agent is ingested leakage-free into the urethra or into the urethra and the bladder through the adapter, then through the external urethral orifice by using overpressure in the dosing device and inserting the (1) tip-part into the external urethral orifice and squeezing the (2) sealing collar in a proper way to the external urethral orifice. Using the adapter and process, catheter-free, painless or pain-reduced and leakage-free bladder filling, bladder rinsing, bladder diagnose, advantageously intravesical (bladder) instillation can be implemented without using catheter. By using the adapter and catheter-free process according to the invention, direct local treatment and diagnose of the urethra can be implemented, which is impossible by using catheter.La materia de nuestra invención es un adaptador para inyección, la instilación de la solución del agente activo y/o de contraste, ventajosamente una solución del fármaco y/o una solución de diagnóstico sin dolor o con dolor r
