Background: :The rhabdosphincter is a thin horseshoe shaped layer of striated muscle which sits outside the smooth muscle layer of the mid urethral zone. Though evidence has been presented for the role of a musculoelastic mechanism involving forward contraction of the suburethral vaginal hammock, this tiny structure , the “rhabdosphincter” is still considered to be the main continence mechanism by many authors.
Aim: :To assess the contribution of the rhabdosphincter to urethral pressure and continence.
Patients and methods: :Four women, mean age 61 years (range 51-71 yrs), parity 0-4 (mean 2.6) with urodynamically demonstrated genuine stress incontinence and no detrusor overactivity (DO). The pressure exerte d by the “rhabdosphincter” was measured during coughing by single Gaeltec microtip transducers before and after surgical dislocation of the suburethral vaginal hammock during a “tension free” midurethral sling operation performed under local anesthesia. The transducer catheter was oriented ventrally at 12 o’clock to maximize the pressure recorded during rhabdosphincter contraction. Five pressure readings were taken from each patient during coughing, taking care to ensure a valid reading at the high pressure zone.
Results: :Intraoperatively, urine loss occurred for the first time, or greatly worsened when the suburethral vagina was disconnected from the urethra. Maximum intraurethral pressure increase recorded on four patients at midurethra was 78, 94,112, and 170% of the preoperative reading.
Conclusions: :The pressure “P” readings are potentially misleading in that they measure only the formula, P=force/area, in this case force from the rhabdosphincter, a weak muscle less important in the closures mechanism of the urethral tube. We hypothesize the rhabdosphincter acts as an adjunctive sealing mechanism.
Corresponding Author: WAGENLEHNER F.|