Few reports have investigated the association between benign prostatic hyperplasia (BPH) patterns and early continence after robot-assisted laparoscopic radical prostatectomy (RARP). Currently, several markers have been identified as being of prognostic significance in the clinical progression of BPH. Intravesical prostatic protrusion (IPP) has been shown to predict the extent of bladder outlet obstruction in pressure flow studies (PFS). Prostatectomy is used for the treatment of both BPH and prostate cancer, with many men opting for radical surgical removal of the prostate. The main aim of this study was to investigate the association between preoperative BPH patterns, preoperative lower urinary tract symptoms and early continence after RARP.

Patients who underwent RARP for clinically localized prostatic cancer (stages cT1c–cT3a N0 M0) between October 2010 and July 2014 at our department were included in the present study. Age, body mass index (BMI), prostate-specific antigen (PSA), Gleason score and clinical stage were recorded. All patients underwent PFS before RARP. PFS was performed by a single examiner using a Solar Gold urodynamic system (MMS USA Inc., Dover, NH, USA) according to the standard methods of the International Continence Society. Detrusor overactivity (DO) was defined as involuntary detrusor contractions during the filling phase of cytometry, or involuntary contractions of any magnitude associated with the urge to urinate. Prostate volume, length of retrourethral enlargement, length of intravesical prostatic protrusion (IPP), and length, width and thickness of the membranous urethra were measured using T2-weighted MRI images. IPP was subsequently categorized into two groups based on IPP length: Group 1, < 5 mm, and Group 2, > 5 mm. The International Prostate Symptom Score (IPSS), Overactive Bladder Symptom Score (OABSS), Quality of Life (QOL) index and number of pads used were evaluated 1, 3, 6 and 12 months after RARP. The study was approved by our university ethics committee.

A total of 119 patients were eligible for this study. Mean values of patient age, BMI, prostatic volume, and PSA were 65 years, 23.6 kg/m2, 28.7 mL, and 9.4 ng/mL, respectively. Nerve sparing was performed bilaterally or unilaterally in 51 patients. Total IPSS score was mild or moderate in 105, and severe in 14 patients before RARP. Mean compliance, mean first desire to void, mean strong desire to void, and mean PdetQmax were 59.6 ml/cmH2O, 152.4 ml, 282.9 ml and 46.6, respectively. DO was identified in 10 patients. The number of patients in Groups 1 and 2 were 71 and 48, respectively. Preoperatively, prostate volume in Group 2 was higher than in Group 1 (24.8 ml vs. 35.8 ml, p<0.05). Similarly, Group 2 patients had higher total IPSS scores (6.8 vs. 9.9, p<0.05) and IPSS-voiding symptom scores (3.7 vs. 6.1 p<0.05) than Group 1 patients. After RARP, there were no significant differences in total IPSS scores, IPSS-voiding symptom scores, IPSS-storage symptom scores, OABSS and QOL index (Figure 1) between the two groups. The rate of achieving zero-pad urinary continence was significantly different between Groups 1 and 2 at one month post-RARP, but after three months, there was no difference between them (Figure 1). Univariate and multivariate logistic regression analyses revealed only nerve sparing and FDV after one month, nerve sparing and membranous urethra width to be significantly associated with continence 12 months post-RARP. However, IPP tended to be involved in urinary incontinence for one month after RARP, although no significant difference was observed between the two groups (Table 1).

In this study, we found low rates of continence after RARP in patients with severe preoperative IPP, although there was improvement in the long term. In addition, although there was no significant difference, IPP tended to be related to early continence in multivariate analysis. Significantly higher IPSS scores were seen in the group with severe as compared to mild IPP. Postoperative IPSS scores improved significantly in relation to preoperative scores in the group with severe IPP, suggesting that RARP might improve voiding symptoms in the long term.

Our data suggests that IPP affects early postoperative urinary continence. Although IPP is strongly associated with preoperative voiding symptoms, it does not predict long-term postoperative incontinence.