The posture in which bladder testing is performed can significantly influence the outcome, a study has found.
According to the authors of the study, “The effect of posture and repetition on urodynamic parameters: A prospective randomized study,” a bladder will be less sensitive and less active if repeated cystometry tests are performed while the patient is lying down. (Cystometry is testing that measures the pressure inside the bladder to see how well it is working.)
“Thus, we suggest that the supine posture is the ideal proper posture for the first filling cystometry,” they wrote.
The study was published in the journal Investigative and Clinical Urology.
Urodynamic tests are considered the gold standard for investigating lower urinary tract symptoms (LUTS) often seen in benign prostatic hyperplasia (BPH). The tests measure how the bladder and urethra store and release urine, and can help predict the outcome of prostatic surgery and influence treatment options. It is, therefore, important that they are done in the posture that best correlates with the patient’s symptoms.
This is the first study to analyze the effect of posture and test repetition on urodynamic parameters.
The team, led by Seung-June Oh, MD, of Seoul National University Hospital in Korea, conducted tests on 71 men with BPH between September 2015 and last August. The men were randomly divided into four groups. All underwent filling cystometry tests twice. During the test, the bladder is slowly filled with warm water using a catheter. Bladder pressure is measured from the rectum using another catheter.
The men in the first group were lying flat during both tests, and those in the second group were standing during the tests. Participants in the third group were on their backs during the first test and standing during the second, and the men in the fourth group were standing during the first test and lying down for the second.
When they were lying down, bladder sensation was decreased, as were fewer involuntary bladder wall smooth muscle contractions. Furthermore, bladder compliance and maximum capacity increased when they were lying down, compared to when they were standing.
During the first test, lying down resulted in a better correlation between overactive bladder and involuntary muscle contraction, and between maximum emptied volume and maximum bladder capacity, the researchers found.
They acknowledged there were limitations to their work.
“First, we recruited only patients with BPH; other diseases, including neurogenic bladder, were excluded. This selection made participants homogeneous, and our results cannot represent other urologic conditions such as urinary incontinence and neurogenic bladder. Moreover, patient symptoms might be more severe compared to that in typical patients with BPH,” they wrote. “Second, we did not perform filling cystometry in the sitting posture. Adding sitting posture would be better choice to have a more complete evaluation of the effect of posture, but it would take larger group and more time.”