Using aseptic precautions, introduce a Jackson cat catheter into the urethra until the obstruction is reached. Withdraw the stilette and introduce 1 ml of buffer solution. After 2 minutes introduce a further 1 ml. After a few minutes it should be possible to pass the catheter into the bladder, but if significant resistance is still present, repeat the instillation of 1 ml portions for up to a further 5 times at intervals of 2 minutes.

Empty the bladder by syringe via the catheter and instill 5 to 20 ml of buffer solution into the bladder dependent upon the condition of the mucosa, as determined by the degree and duration of the obstruction, the degree of haematuria and the number of crystals in the urine. In the case of multiple microcalculi the catheter should be held in situ during hospitalisation for 4–7 days.