Int Urogynecol J (1997) 8:69-73 © 1997 Springer-Vertag London Ltd International Urogynecology Journal Original Article Role of the Pelvic Floor in Bladder Neck Opening and Closure II: Vagina P. E. Papa Petros 1 and U. Ulmsten 2 1Royal Perth Hospital, Perth, Western Australia; 2Academic Hospital, University of Uppsala, Uppsala, Sweden Abstract: The aim of the study was to examine the role of vaginal stretching during bladder neck opening and closure. The study group comprised 12 patients with GSI and 4 controls. The position of the bladder neck relative to the vagina was assessed in the resting, straining and 'squeezing' positions using video-radiolo- gical studies. Radio-opaque dye was instilled into the bladder, vagina, rectum and levator plate. Vascular clips applied to the midurethral, bladder neck and bladder base parts of the anterior vaginal wall assisted in determining differential movements of these parts of the vagina during bladder neck opening and closure. The suburethral vagina (hammock) was shown to stretch downwards and forwards during straining, and downwards and backwards during micturition. The bladder neck, upper part of the vagina and the rectum were stretched backwards and downwards in an identi- cal manner during straining and micturition, apparently in response to backward contraction of the levator plate and downward angulation of its anterior lip. All organs were stretched upwards and forwards during 'squeez- ing'. The findings support the hypothesis that, during stress and micturition, selective pelvic floor contractions stretch the vagina against intact pubourethral and utero- sacral ligaments to assist opening and closure of the urethra and bladder neck. Keywords: Continence mechanism; Integral Theory; Pelvic floor; Vagina; Pubourethral; Uterosacral Correspondence and offprint requests to: Dr P. E. Papa Petros, Suite 14 A Surgicentre, 38 Ranelagh Crescent, South Perth, WA 6151, Australia. Introduction Historically, the role of the vagina has been limited to that of reproduction [1], but recently another rote has been hypothesized: tensioning of the suburethral part of the vagina ('hammock') by the anterior portion of the pubococcygeus muscle may be an important element in urethral closure [2,3], and act as an anchoring mechan- ism for bladder neck closure [2-4]. Transmission of intra-abdominal pressure during effort is still generally considered to be the ultimate mechanism for urethral and bladder neck closure [4,5]. This hypothesis has recently been challenged. Ultrasound, radiological and pressure studies have demonstrated that urethral closure on effort was most probably affected by the posterior urethral wall moving forwards against the anterior urethral wall [2,6]. Observations of live patients during intravaginal slingplasty (IVS) oper- ations [6] have shown that an adequately tight subureth- ral vaginal hammock is a crucial factor in urethral closure. Even with opened-out suburethral vaginal flaps, a rise in the intraurethral pressure of up to 170% did not prevent urine leakage [6]. The importance of the arcus tendineus fasciae pelvis (ATFP) as a supporting structure of the vagina and bladder neck is well documented [4]. We believe that the ATFP also assists the btadder neck closure mechan- ism by rapid posterior stretching of the upper vagina against the intact PUL. This movement is probably activated by contraction of those elements of the levator plate situated just behind the ischial spine. The import- ance of the pubourethral ligament for urinary conti- nence has, however, been questioned [4], mainly because the PUL is some distance from the bladder neck. Our opinion that the PUL is also important for urethral closure is based on our experience during the