Perineal prostatectomy and anal incontinence Guilger NR et al. rectal sensitivity, and the anatomical and functional integrity of the anal sphincter and pelvic floor muscles. This complex interaction of mechanisms is also affected by other individual characteristics and behaviors.9 Vector volume analysis allows the visualization of the pressure conformation in the anal canal, and a high sphincter asymmetry index has been associated with sphincter defects and anal incontinence.9,10 The sphincter asymmetry index is based on an evaluation of the radial distribution of pressure along the anal canal. This para- meter has primarily been used for research purposes, and it was first used to demonstrate anatomical sphincter disruption.11-13 This index has subsequently been used to evaluate continence status after different therapeutic procedures.8,14 The prevalence of anal incontinence in the elderly population is approximately 11%, and the most important risk factor for this disorder is age.15 Anal incontinence has a negative impact on a patient’s confidence, self-image and social life, which contributes to the development of depressive symptoms.16 The aim of this study was to evaluate the effects of perineal access on anal continence mechanisms after perineal prostatectomy. METHODS Overall study design and setting A prospective before-after study17 was conducted to evaluate anal incontinence in patients with prostate cancer. All patients were sequentially selected in July 2008 and all perineal prostatectomy performed in the period between August 2008 to October 2008 at Fundac¸a˜o Amaral Carvalho. The procedures were performed by the same surgeon. Before surgery and eight months after surgery, a clinical evacuation evaluation, including the Cleveland Clinic Incontinence Score (CCIS),9 the Fecal Incontinence Quality of Life Score (FIQLS),18 and anorectal manometry,19 was used for the assessment. This study was approved by the Ethics Committee in Research of the two participating institutions, the Hospital das Cl´ınicas da Faculdade de Medicina da Universidade de Sa˜o Paulo, Sa˜o Paulo, SP and Fundac¸a˜o Amaral Carvalho, Jau´ , SP. Informed written consent was obtained from all volunteers. Sampling and subjects Patients with previous perineal and anorectal diseases and anal surgery were excluded. All consecutive patients who were diagnosed with prostate cancer and indications20 for perineal prostatectomy were evaluated and underwent surgical procedures using the same standardized techni- que20,21 with the same team of urologists at Fundac¸a˜o Amaral Carvalho, Jau´ , SP. Measures All patients were evaluated using the clinical evacuation examination, CCIS,9 FIQLS,22 and anorectal manometry19 before surgery and eight months after surgery. The period of eight months after surgery was chosen based on previous studies to ensure that transitory symptoms would not be overestimated.22 All parameters were assessed by the same researcher. Anal incontinence was considered to be mild for a CCIS of 1-8 and moderate/severe for a CCIS greater than 9; an index of zero corresponds to complete continence. 2008 CLINICS 2011;66(12):2007-2012 Anorectal manometry Anorectal manometry was performed using an 8-channel water perfusion system (DynamedH model Dynapack II Slim; ProctoMaster version 7.0 software). A flexible plastic catheter with a diameter of 0.8 cm was used as a probe. The catheter contained eight channels that were radially distributed; each channel was perfused with distilled water at a constant flow rate of 0.56 ml/minute/channel using a pneumo-hydraulic system with hybrid nitrogen and electric propulsion. Channel one was positioned posterior to the anal canal (zero degree), and the other channels were sequentially positioned clockwise. The following parameters were evaluated: resting pres- sure (mmHg), maximum squeeze pressure (mmHg), high pressure zone (cm), fatigue rate (mmHg/min), fatigue rate index (min), sphincter asymmetry index (%), rectoanal inhibitory reflex, rectal sensory threshold (ml), and max- imum tolerated rectal volume or capacity (ml). Pressure parameters were collected during intermittent catheter withdrawal 6.0 to 1.0 cm from the anal verge. The functional anal canal length comprised the extent of pressures equal to or greater than 50% of the highest mean value that was achieved among the eight channels at the same level. The catheter was placed 2 cm from the anal verge to evaluate the sustained voluntary contraction and the Resting Anal Inhibitory Reflex (RAIR) test. Finally, the catheter was placed and moved 6.0 cm from the anal verge, and the rectal sensitivity and capacity were evaluated by inflating the balloon with water at room temperature. Rectal sensitivity was considered to be the minimum amount of liquid that was perceived by the patient, and the maximum tolerated capacity was considered to be the maximum amount of liquid tolerated before an urge to defecate occurred. Statistical analyses Fisher and McNemar tests were employed to analyze qualitative variables. Quantitative variables were analyzed using the Student’s t-test and the paired-sample Wilcoxon test. A sample size of 18 patients undergoing perineal prostatectomy provide an 85% power to detect 15-mmHg and 1-point differences in the resting pressure and the FIQLS and incontinence index scores, respectively, before and after surgery. A two-tailed significance level of 0.05 was considered to be statistically significant. RESULTS A total of 30 consecutive patients with prostate cancer and indications for perineal prostatectomy completed the pre- operative evaluation from May to July 2008. However, one patient underwent a retropubic prostatectomy, and two patients were submitted to radiotherapy. These three patients were excluded from the study. Postoperative evaluations were performed approximately eight months after surgery. Four patients did not attend the postoperative evaluation, and consequently, 23 patients completed all of the steps of the postoperative evaluation. Thus, this study was conducted in 23 patients with a mean age of 66 years (range, 54-72) years, a mean prostate- specific antigen value of 8.8 ng/ml (range, 3.6 to 22.1 ng/ ml), a mean Gleason Score of 6 (range 6-7) and a mean prostate weight at ultrasound of 34.4 g (range, 24-54 g). The patients reported no change in anal continence after early post-operative perineal prostatectomy.