Does the patient's position influence the detection of detrusor overactivity?

The demonstration of preoperative detrusor overactivity (DO) with associated overactive bladder symptoms (OAB) is known to have an adverse effect on surgery performed for stress incontinence or for prostatic obstruction. The purpose of this review is to examine the best position, when filling the bladder during urodynamics, to demonstrate detrusor overactivity and reproduce the OAB symptoms, when the demonstration of DO might be important.

MEDLINE and PUBMED literature searches were performed, spanning the period from 1956 to August 2005 using the keywords "detrusor overactivity" or "detrusor instability" combined with "posture or position or standing or sitting" and "urodynamics." Other studies were identified by reviewing secondary references in the original citations.

Sixteen studies looked at the effect of position on the detection rate of DO. There is good consistency between the studies analyzed. All but two [Ramsden et al., Br J Urol 49:633-9, 1977; Choe et al., J Urol 161:1541-4, 1999] showed a clear effect, with an increase in DO when the patient is filled in the vertical position or is asked to sit or stand, with a full bladder, after being filled supine. Performing the urodynamics (UDS) in the supine position would have missed a large proportion of DO diagnoses ranging from 33% to 100%.

This review confirms that the patient's position is a significant variable during urodynamics and that supine cystometry will fail to detect a significant percentage of patients with DO. We suggest that all patients should be filled sitting or standing, unless physically disabled. It seems desirable for the International Continence Society (ICS) to extend its "Good urodynamic practice guideline" [Schafer et al., Neurourol Urodyn 21:261-74, 2002] to cover this important issue.