Introduction: Previous measurement of the male external urethral sphincter complex (EUSC) length by magnetic resonance imaging and urethral pressure profilometry did not consider the intraprostatic portion, although its role for urinary continence has been demonstrated. The aim of our study was to verify the feasibility of a morphological evaluation of the EUSC by transrectal ultrasound (TRUS). Materials and Methods: Data from 52 men that underwent TRUS were prospectively collected. The EUSC was identified in the midline sagittal plane. Total and intraprostatic EUSC length and prostate volume were measured. Results: EUSC appears as a hypoechoic area surrounding the urethra. The proximal end was identified between the verumontanum and the prostate apex by the net change in prostate echo patterns, while the distal end was identified by voluntary contraction of the external anal sphincter. Mean total and intraprostatic EUSC lengths were 20.17 and 3.78 mm, respectively. Total EUSC length presented a weak correlation with prostate volume (r = 0.41; p = 0.003), while the intraprostatic portion had a stronger correlation (r = 0.60; p = 0.001). Conclusions: The evaluation of the EUSC is feasible by TRUS, and length measurement should include the intraprostatic portion. Potential clinical application should be the preoperative assessment of the risk of urinary incontinence in men undergoing radical prostatectomy.

Keywords:
Urethral sphincter, Transrectal ultrasound, Prostate
1.
Myers RP, Cahill DR, Devine RM, King BF: Anatomy of radical prostatectomy as defined by magnetic resonance imaging. J Urol 1998;159:2148–2158.
2.
Hammerer P, Michl U, Meyer-Moldenhauer WH, Huland H: Urethral closure pressure changes with age in men. J Urol 1996;156:1741–1743.
3.
Paparel P, Akin O, Sandhu JS, Otero JR, Serio AM, Scardino PT, et al: Recovery of urinary continence after radical prostatectomy: association with urethral length and urethral fibrosis measured by preoperative and postoperative endorectal magnetic resonance imaging. Eur Urol 2009;55:629–637.
4.
Myers RP: Practical surgical anatomy for radical prostatectomy. Urol Clin North Am 2001;28:473–490.
5.
Hammerer P, Huland H: Urodynamic evaluation of changes in urinary control after radical retropubic prostatectomy. J Urol 1997;157:233–236.
6.
Oelrich TM: The urethral sphincter muscle in the male. Am J Anat 1980;158:229–246.
7.
Lee SE, Byun SS, Lee HJ, et al: Impact of variations in prostatic apex shape on early recovery of urinary continence after radical retropubic prostatectomy. Urology 2006;68:137–141.
8.
Wallner C, Dabhoiwala NF, DeRuiter MC, Lamers WH: The anatomical components of urinary continence. Eur Urol 2009;55:932–944.
9.
Coakley FV, Eberhardt S, Kattan MW, Wei DC, Scardino PT, Hricak H: Urinary continence after radical retropubic prostatectomy: relationship with membranous urethral length on preoperative endorectal magnetic resonance imaging. J Urol 2002;168:1032–1035.
10.
McLaughlin PW, Narayana V, Meirovitz A, Troyer S, Roberson PL, Gonda R Jr, et al: Vessel-sparing prostate radiotherapy: dose limitation to critical erectile vascular structures (internal pudendal artery and corpus cavernosum) defined by MRI. Int J Radiat Oncol Biol Phys 2005;61:20–31.
11.
Osman Y, El-Tabey N, El-Ghar MA, Abdel-Latif M, El-Bahnasawy M, Mosbah A, et al: Impact of pre-operative MRI-measured membranous urethral length on urinary continence after radical cystectomy and orthotopic substitution: clinical and urodynamic evaluation. Int Urol Nephrol 2007;39:149–154.
12.
Kamoi K, Gill IS, Haber GP, Lin YC, Frota R, et al: Transrectal ultrasound measurement of membranous urethral length as a predictor of urinary continence after laparoscopic radical prostatectomy (abstract 118). 22nd EUS Annu Meet, Anaheim, 2007.
13.
Shore ND, Dineen MK, Saslawsky MJ, Lumerman JH, Corica AP: A temporary intraurethral prostatic stent relieves prostatic obstruction following transurethral microwave thermotherapy. J Urol 2007;177:1040–1046.
14.
Stolzenburg JU, Schwalenberg T, Horn LC, Neuhaus J, Constantinides C, Liatsikos EN: Anatomical landmarks of radical prostatectomy. Eur Urol 2007;51:629–639.
15.
Walz J, Graefen M, Huland H: Basic principles of anatomy for optimal surgical treatment of prostate cancer. World J Urol 2007;25:31–38.
16.
Myers RP: Male urethral sphincteric anatomy and radical prostatectomy. Urol Clin North Am 1991;18:211–227.
17.
Linker DG, Tanagho EA: Complete external sphincterotomy: correlation between endoscopic observation and the anatomic sphincter. J Urol 1975;113:348–352.
18.
Al-Rifaei MA, Zaghloul S, Al-Rifaei AM: Bulboprostatic anastomotic urethroplasty with preservation of potency: anatomical study, operative approach and clinical results. Scan J Urol Nephrol 2005;39:163–168.
19.
Schlomm T, Heinzer H, Steuber T, Salomon G, Engel O, Michl U, Haese A, Graefen M, Huland H: Full functional-length urethral sphincter preservation during radical prostatectomy. Eur Urol 2011;60:320–329.
20.
Nguyen MM, Kamoi K, Stein RJ, Aron M, Hafron JM, Turna B, et al: Early continence outcomes of posterior musculofascial plate reconstruction during robotic and laparoscopic prostatectomy. BJU Int 2008;101:1135–1139.
© 2012 S. Karger AG, Basel
2012
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