Aug 4 2014
By Joanna Lyford, Senior medwireNews Reporter
Japanese researchers have identified certain pelvic anatomic features in men who have undergone radical prostatectomy (RP) that are associated with specific lower urinary tract symptoms (LUTS).
The team reports that urinary pooling inside the urethra may cause urgency, while the postoperative membranous urethral length (MUL) and depth of urethrovesical junction are linked to urinary incontinence.
“These findings suggest that the morphology of the bladder and urethra after RP is associated with LUTS”, write Nobuhiro Haga (Fukushima Medical University School of Medicine) and colleagues in Urology.
The researchers used magnetic resonance imaging to evaluate 53 consecutive men who had undergone RP at least 6 months earlier. All men were also assessed for LUTS and urinary function using the International Prostate Symptom Score (IPSS), a quality of life (QoL) index, uroflowmetry and ultrasound.
The men’s median age was 69 years and they had undergone RP an average of 20 months earlier. Postoperatively, the mean maximum flow rate was 18.3 mL/min, mean postvoid residual volume was 24 mL, mean total IPSS score was 8.8 and mean QoL score was 2.5.
On univariate analysis, postoperative MUL was significantly associated with QoL index and continence grade, while urinary pooling inside the urethra was significantly associated with both frequency and urgency on the IPSS.
Multivariate analysis confirmed the associations between MUL and QoL index and between urinary pooling and urgency; additionally, postoperative MUL, postoperative depth of urethrovesical junction and postoperative urinary pooling inside the urethra were all significantly associated with continence grade.
Multivariate analysis also revealed an independent association between age and maximum flow rate.
Haga et al say that their study is the first to report that pelvic anatomic changes after RP are associated with LUTS, assessed both subjectively and objectively.
They hypothesise that the link between urinary pooling and urgency is due to facilitation of the micturition reflex induced by a deficient urethral sphincter, whereby urine leakage into the urethra stimulates afferent nerve activity of the proximal urethra.
Meanwhile, the link between postoperative MUL and both continence and QoL, which was not seen preoperatively, suggests that leaving a long MUL after RP is “crucial for avoiding urinary incontinence, which seems to mostly affect QOL”, they say.
The researchers conclude: “Avoiding damage to the nerves involved in continence to prevent the inflow of urine into the urethra, preserving the MUL, and developing surgical procedures to prevent descent in the bladder neck during surgery are therefore recommended to minimize LUTS after RP.”
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