Hypothesis / aims of study
Artificial Urinary Sphincter is still treatment of choice in male incontinence. One merit of AUS is in its circumferential supporting of urethra  providing more even pressure around the urethra compared with male sling system. Intraoperative cycling test is performed under direct visualization with endoscopy to check the device function, appropriate opening and complete coaptation of sub-cuff urethra [2,3]. Whereas, complete coaptation with blanching sign of sub-cuff urethra is a condition that must be checked for all cases of surgery, the degree of opening of sub-cuff urethra is various depending on the patients. There is concern that incomplete opening of sub-cuff urethra may cause the urethral erosion, atrophy and voiding symptoms. In addition, immediate postoperative urinary retention caused by tissue edema is one of the short-term complications of AUS. However little data is available on the surgical outcome in association with intraoperative endoscopic findings of sub-cuff urethra. We investigated whether the opening degree of sub-cuff urethra observed during intraoperative cycling test might predict the lower urinary tract symptoms or surgical complication after AUS implantation.
Study design, materials and methods
With approval of institutional review board, male AUS cases applied around bulbar urethra from January 2009 to January 2018 were retrospectively investigated out of a single surgeon cohort. Cases only with non-neurogenic stress urinary incontinence were included in assessment. The opening degree was calculated using Picture Achieving and Communication System (Centricity® PACS, GE Healthcare Co.). On the endoscopic image, actually opened sub-cuff area was delineated. Imaginary circle having the same diameter as the longest end-to-end length of actual opened area was delineated on a constant resolution image. A value obtained by dividing the number of pixels of the actual opened area by the number of pixels of imaginary circle was regarded as opening degree of sub-cuff urethra. Patient assessment was performed periodically after device activation at out-patient clinic. Postoperative lower urinary tract symptoms were assessed using international prostate symptom score (IPSS), overactive bladder symptom score (OABSS), international consultation on incontinence questionnaire (ICIQ), and incontinence severity index developed by Sandvik (SANDVIK-ISI). The correlation of opening degree of sub-cuff urethra and the scores of each questionnaire was analyzed at each follow up point, using Spearman's rank correlation test. Intergroup comparison was performed with Mann-Whitney U test (SPSS version 23, Chicago, IL, USA).
128 patients with available image data, observed without traumatic urethral erosion, were evaluated. Median age at AUS implantation was 73.9 (57.9~84.9) years, median follow up period was 37.7 (4.5~111.1) months after device implantation. 121 (94.5%) patients had post-radical prostatectomy urinary incontinence, 5 (3.9%) patients had incontinence after transurethral prostatic surgery, 1 (0.8%) patient had post-radiation incontinence, and 1(0.8%) patient had sphincter deficiency associated urethral injury. 78 (60.9%) received 4.0cm-cuff, 28 (21.9%) received 4.5cm-cuff, 10(7.8%) received 3.5cm-cuff, 6 (4.7%) received 5.0cm-cuff and 6 (4.7%) received 5.5cm-cuff. The median opening degree was 59.5% (30%~100%). There was significant correlation between the opening degree and the applied cuff circumference (Rho=0.235, P=0.008). 21 (16.4%) patients experienced urinary retention immediately after removal of urethral catheter on the first postoperative day having post-void residual more than 100ml. However, the voiding function of all the patients recovered within postoperative 2~7 days. There was no significant difference in the opening degree of sub-cuff urethra regarding immediate postoperative urinary retention; median 62.1% for urinary retention group, 58.5 % for the other patients (P=0.311). 4 (3.1%) patients experienced urethral atrophy or non-traumatic erosion requiring revision. There was not statistically significant difference in the opening degree of sub-cuff urethra regarding atrophy or erosion; median 48.2% for atrophy group, 59.5% for the other patients (P=0.109). In correlation analysis, there was no significant negative correlation between the opening degree of the sub-cuff urethra and postoperative lower urinary tract symptom scores (Table 1). On the other hand, significant positive correlation was observed in some storage and voiding symptoms.
Interpretation of results
We could not observe significant negative correlation between the opening degree of the sub-cuff urethra and the postoperative lower urinary tract symptom scores, suggesting that incomplete opening of the sub-cuff urethra is not necessarily associated with aggravation of postoperative lower urinary tract symptoms. Paradoxically, opening degree of sub-cuff urethra had positive correlation with some storage or even voiding symptoms. However, as the complete coaptation was verified in every case, these results may not be clinically significant. However, although not statistically significant, absolute median value of opening degree in patients with atrophy or erosion was smaller than that of the other patients.