Objectives: The high-pressure zone of the urethra (HPZ), which is crucial for the continence mechanism, extends between the point of the maximum urethral closure pressure and the urethral knee, and has been calculated to lie between 53% and 72% of the functional urethral length. According to recent studies the best results of suburethral slings are achieved when tapes are positioned under this zone. The aim of the study was to determine the location of tapes relative to the urethral length in patients seeking help due to recurrent stress urinary incontinence (SUI) following sling procedures.
Material and methods: The study group comprised 61 patients suffering from recurrent SUI following suburethral slings performed from 6 months to 5 years earlier Forty-nine (80.3%) women were initially treated with a transobturator sling and 12 (19.7%) with a retropubic procedure. Twenty patients had the original sling performed at our department whereas, the other 41 in other institutions. The position of the tapes was determined at the sagittal plane by 3-D transvaginal ultrasound using a linear transducer The length of the urethra was measured from the bladder neck to the external urethral meatus following the urethral lumen, taking into account its curve. The position of the tapes relative to the percentage of the urethral length was calculated assuming the bladder neck as the proximal end of the urethra. The reference point was set at the midpoint on the tape.
Results: Only 13 (21.3%) patients had tapes positioned at 50%-75% of the urethral length. In 45 (73.8%) of women examined the tapes were found under proximal half of the urethra and in 3 (4.9%) distally to the 75% of the urethral length.
Conclusions: In most patients in whom slings procedures proved unsuccessful the tapes are located under the proximal half of the urethra, that is outside the HPZ The position of a.tape outside the HPZ may be considered as a cause of suburethral sling failure.