Working of BCG in bladder

BCG is only present in the bladder for about a day. It works by "kicking up" the immune system so that it becomes more sensitive to "intruders" such as cancer cells that shouldn't be in the tissue and gets rid of them.
Almost as if the bladder tissue develops an "allergy" to foreign cells. As you have more BCG treatments, the immune system gets more reactive to it...sort of as if the first dose was sort of an irritant and then as more is administered it becomes more and more sensitive to it. That is a simplistic explanation, but gives you an idea.

Because of the bladder tissue's reaction to the BCG it can become quite irritated. There would be no point in having cystoscopy unless the bladder has healed from the irritation, because it would look as if there were something wrong. Several times my bladder was still irritated at six weeks and we had to do cystoscopy again a few weeks later.

Sara Anne