Original Article

How the midurethral sling works


Pelviperineology 2018;37(4):112-113

Though the midurethral sling (MUS), the gold standard operation for cure of urinary stress incontinence has been in use for almost 30 years, few surgeons understand the anatomical basis for how it works. The original explanation given in 1990 was that the pubourethral ligament (PUL) weakened due to birth related collagen damage. The MUS tape shortened and reinforced the PUL by creation of a collagenous neoligament. This neoligament restored the distal and proximal urethral closure mechanisms. The closure mechanisms were further validated by simultaneous measurement of intra and extra urethral and bladder pressures, video ultrasound imaging after placing a haemostat on one side of the vagina to support the damaged PUL and in 2014 by a mathematical model which showed that any explanation which relied on the pressure equalisation theory would need a pressure The midurethral sling (MUS) is the most studied operation in the history of Urogynecology, validated by more than 2000 studies. Few know its history, fewer how it works. Even today, what some consider as the peak body for incontinence science, the International Consultation for Incontinence, attributes urethral closure to pressure transmission theories, none of which can explain why a tape placed at midurethra can restore continence. Absent from ICI is any mention of the Integral Theory (1) on which the first commercial MUS, the TVT was based (2). The aim of this comment is to present the original scientific work which led to the MUS and further experiments which sought to validate the original mechanisms proposed.

Keywords: Midurethral sling,Integral theory,Pressure transmission,Pubourethral ligament