Ko te catheter mimi he ngongo ka kuhu ki roto i te ngongo ma roto i te urethra hei whakaheke i te mimi. I muri i te whakaurunga o te ngongo ki roto i te ngongo, he poihau kei te taha o te upoko o te ngongo hei whakatika i te ngongo Ka noho tonu te ngongo ki roto i te ngongo, kare i te ngawari ki te puta ki waho, ka honoa te ngongo whakaheke ki te putea mimi hei kohi mimi. E ai ki nga matrial rerekee, nga ngongo mimi ki roto i te ngongo rapa maori, ka taea te wehea te ngongo rapa silicone, te catheter polyvinyl chloride ranei (PVC catheter).