Can bladder surgery on a 78year old male fix a weak 3 liter bladder. it prefers to retain the water! prostate seems to be not swollen?

If the urinary retention isn't caused by prostate or bladder outlet obstruction, I'm unsure what type of bladder surgery could relieve chronic urinary retention. I've had such patients who had to self catheterize three times daily to avoid constant indwelling foley catheter use. Of course, your urologist can answer your question best.

The cause of 'weak' bladder has to be found before deciding how and what of treatment