title: Impact of preoperative and postoperative membranous urethral length measured by 3 Tesla magnetic resonance imaging on urinary continence recovery after robotic-assisted radical prostatectomy.
abstract: BACKGROUND
  We sought to investigate the impact of preoperative and postoperative membranous urethral length (MUL) on urinary continence using 3 Tesla (3T) magnetic resonance imaging (MRI) after robotic-assisted radical prostatectomy (RARP).
  
  
  METHODS
  Between 2008 and 2013, 190 men with RARP underwent preoperative and postoperative MRI. Patients who received adjuvant radiotherapy or who were lost to followup were excluded, leaving 186 patients eligible for analysis. Preoperative MUL was estimated from the prostate apex to the penile bulb, while postoperative MUL was estimated from the bladder neck to penile bulb. Patients with no pads or protection were considered to have complete continence. Logistic regression analysis was used to identify predictors associated with urinary incontinence at six and 12 months.
  
  
  RESULTS
  Age was commonly associated with urinary incontinence at six and 12 months. In addition, diabetes mellitus (DM) was another factor associated with urinary incontinence at 12 months. When adjusting these variables, preoperative MUL ≤16 mm (95% confidence interval [CI] 1.01-1.14; p=0.022), postoperative MUL ≤14 mm (95% CI 1.16-9.80; p=0.025) and percent change of MUL >18% (95% CI 1.17-7.23; p=0.021) were significantly associated with urinary incontinence at six months. However, at 12 months, preoperative MUL ≤13.5 mm (95% CI 1.85-19.21; p=0.003) and postoperative MUL ≤13 mm (95% CI 1.24-13.84; p=0.021) had impacts on urinary incontinence, but not percent change of MUL.
  
  
  CONCLUSIONS
  Preoperative and postoperative MUL were significantly associated with urinary continence recovery after RARP. Therefore, efforts to preserve MUL are highly recommended during surgery for optimal continence outcomes after RARP.
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Wan
authors.initials: W
authors.lastname: Song
authors.affiliation: Department of Radiology and Centre for Imaging Science, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Chan Kyo
authors.initials: CK
authors.lastname: Kim
authors.affiliation: Department of Radiology and Centre for Imaging Science, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Byung Kwan
authors.initials: BK
authors.lastname: Park
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hwang Gyun
authors.initials: HG
authors.lastname: Jeon
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Byong Chang
authors.initials: BC
authors.lastname: Jeong
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Seong Il
authors.initials: SI
authors.lastname: Seo
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Seong Soo
authors.initials: SS
authors.lastname: Jeon
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Han Yong
authors.initials: HY
authors.lastname: Choi
authors.affiliation: Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hyun Moo
authors.initials: HM
authors.lastname: Lee