Doctors Lounge - Urology Answers
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Forum Name: Urology Topics
|jgs - Wed Dec 02, 2009 8:33 am||
I visited my family doc a few weeks ago with back pain and problems with incontinence. Ultrasound showed hydronephrosis but no problems with my bladder emptying. I was referred to a urologist, and had urodynamics and a CT so far (cystoscopy/consultation to follow in a week). The tech who did the urodynamics said I had about 8 oz of urine that I didn't empty... How come the ultrasound showed I was able to and the urodynamics showed something else? I also have traces of protein in urine, slightly elevated white blood cell count, and occasional pain in my pelvic area as well. I also have recently been treated for a urinary infection. I have had kidney/bladder problems since birth, and a few years ago I had kidney or bladder stones, but was nauseous and very sick then, with no problems controlling urine. I'm wondering if it is the same thing this time, and is incontinence related to it, or is it a separate issue?
|Dr.M.Aroon kamath - Wed Jun 30, 2010 8:07 am||
There are 2 methods for estimating post-void residual (PVR) urine volume:
- urethral In-and-out catheterization after asking the patient to void and
- bladder ultrasound.
Urinary bladder scanning using portable ultrasound scanners is routinely used to assess urinary retention and incontinence because, it is noninvasive and there is no risk of injury or discomfort to the patient. Bladder emptying is assessed by measuring the presence of residual urine in the bladder immediately after voiding (post-void residual is the amount of urine left in the bladder within 10-15 minutes after voiding).
A PVR volume of less than 50 mL is considered adequate bladder emptying. In the elderly males, between 50 and 100 mL is considered normal. In general, a PVR volume >200 mL is considered abnormal and could be due to incomplete bladder emptying or bladder outlet obstruction.
One study came to the following concusion: "When using a portable ultrasound bladder scanner to assess the PVR urine volume, health care professionals should be aware of the possibility of a falsely elevated PVR. Any difference or discrepancy between the results of the bladder scanner and the in-and-out catheter should alert the health care professional to look for cystic and pelvic pathology, which can present as falsely high PVR volumes".
( http://www.cfp.ca/cgi/content/full/55/2/163 ).
Therefore one must be aware of the possibility of falsely elevated postvoid residual volumes during ultrasonographic evaluation.
Studies in pediatric cases have shown that the time lag between the ultrasound measurement and the actual urine volume measurement following catheterization is one of the major sources of error in evaluation of the bladder urine volumes, especially for small volumes. If the interval is long,falsely raised PVR volumes will inevitably result.
(http://www.nature.com/ki/journal/v55/n/ ... 0762a.html)
I hope this answers some of the points you have raised.
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