Surgical anatomy of the bladder neck sphincter and its significance for vaginal surgery of stress incontinence

Abstract

The bladder closure mechanism works under the influence of a hydro-aerodynamic force that presses downward ("stress"). This "stress" is caused by the relative weakness of the pelvic floor. The structures running through the urogenital hiatus are compressed by the rectococcygeal and pubo-coccygeal muscles, which close the hiatus. The urogenital diaphragm bridges the slit in the levator ani muscles. It is made of the perineal membrane, the superior fascia, and the smooth and striated muscle lying between the two (M. sphincter urethrovaginalis, M. compressor urethrae). The superior fascia is an extension of the intraabdominal interior parietal fascia. The intraabdominal pressure stabilises the position of the urethrovesical region by pressing the intraabdominal contents and the subperitoneal connective tissue etc. closely together. The visceral fascia, the pubourethral ligaments, and above all, the connection to the superior fascia of the pelvis diaphragm anchor and regulate the paraurethro-vaginal region. The decompensation of this stress mechanism, usually caused by previous birth injury, leads to varied degrees of prolapse and incontinence. A rational therapy is the reconstruction of the damaged structures of the pelvis floor (diaphragma urogenitale, diaphragma pelvis, perineum etc.) in a complete individualised vaginal surgical reconstruction ("diaphragm repair"). This procedure makes a direct visualisation of the local situation and a control of the indication for surgery possible. If the suspensory apparatus is well anchored to the pelvis wall, reconstruction can be achieved. If this is not the case, a more sophisticated repair is necessary. If the indication is not correct and the limits of this method are ignored, or, if surgery is technically inadequate, this method will fall into disrepute.