The mechanics of urethral closure, incontinence and midurethral sling repair. Part 1 original experimental studies. (1990).

AIMS: To summarize the mechanics of urethral closure, incontinence, and midurethral sling repair, a work in 3 parts Part 1. Original scientific studies (1990). Part 2. Experimental validation of reliance of the closure mechanisms on a competent PUL (1993-2003). Part 3. Surgery (1990-2016).

METHODS

Part1. Two unrelated observations in the mid 1980s led to the discovery of the MUS: a hemostat applied on one side of the midurethral area of the vagina, controlled urine loss on coughing without bladder neck elevation; an implanted Teflon tape cause a collagenous reaction. It was hypothesized that urinary stress incontinence (USI) was caused by collagen loss in the pubourethral ligament (PUL) and a tape implanted in the exact position of PUL would reinforce it and cure USI. A tape removable at 6 weeks was configured as an inverted "U" in the vagina and lowered sequentially.

RESULTS

At a certain point, the patient was continent on coughing but was able to pass urine freely. This proved the mechanism for continence was not obstructive. Post-op xrays showed no elevation of bladder neck. This invalidated Enhorning's Theory. Ultrasound showed closure of distal urethra from behind and descent of vaginal fornix on straining. This indicated there were two closure mechanisms, distal urethral, and bladder neck. Three months following sling removal, there was a 50% failure rate.

CONCLUSIONS

The 1990 results indicated a permanent sling was required for the MUS. Further proofs were required for the proposed musculoelastic mechanisms.