LARGE POST-VOID RESIDUAL:
Dear Sumner:
During an evaluation of a 73 year old man for excessive flatulence, I found on an ultrasound study that he had a post-void residual of 400ccs. of urine. Indeed, until this was pointed out to him, he was not even aware that he had a “problem.” He says that he is voiding without difficulty, and although he gets up once during the night and his urinary stream is not as fast as that of his grandson (they sometimes see who can finish first: his grandson almost always wins the race), he is not distressed with the situation. Should further diagnostic studies be done? Does the presence of a large post-void residual of itself dictate the necessity for some form of intervention therapy? I’d appreciate having your opinion on this matter.
Dear Don:
Thanks for the opportunity of seeing your patient for evaluation of his post-voiding residual urine (which you picked up during an abdominal ultrasound study, the study having been done for his problem with excess flatulence). The question always arises as to “how aggressive must we get?” Basic urological tenets teach us that a large post-void residual can lead to “back pressure” and resultant impaired drainage of the kidneys, with the potential for renal failure. Many urologists would advise drainage of the bladder with a catheter. However, your patient has no associated distention of his renal collecting systems or ureters, his renal function studies are completely within normal range, and there have been no associated infections of the urinary tract. As you know, he is not at all distressed with his voiding pattern, and I feel quite comfortable in holding off on further urological workup at this time. If, however, there is evidence of developing problems, then consideration would be given to establishing more satisfactory drainage of the urine (e.g. via a catheter initially). I think it wise that you obtain another renal ultrasound study, to include a post-voiding film, in about 6 months, earlier if symptoms referable to the urinary tract occur before then. Please keep me informed re these follow-up studies and feel free to call me at any time.
