Original Article

Experimental Study No. 8: Stress urinary incontinence results from muscle weakness and ligamentous laxity in the pelvic floor

  • PETER PETROS
  • MICHAEL SWASH
  • BYRON KAKULAS

Pelviperineology 2008;27(3):107-109

AIM:

To assess the roles of muscle damage and of ligamentous laxity in urinary stress incontinence.

PATIENTS AND METHODS:

Muscle biopsies (n = 47) were taken from the anterior portion of pubococcygeus muscle during the “tension-free” midurethral slingplasty procedure, an operation which corrects laxity in the pubourethral ligament. There were 38 multiparas with stress incontinence, and 9 nulliparas with mainly urge and frequency. The biopsies were examined blindly for evidence of muscle damage. Surgical cure was blindly assessed by means of a cough stress pad test.

RESULTS:

The results were correlated only after post-operative assessment. In total, 33 of the 39 patients with stress urinary incontinence were cured. In 17 biopsies of multiparas and in one nullipara the sample consisted only of a fibrous connective tissue scar. Fifteen of these 17 multiparas with stress urinary incontinence were cured postoperatively. Of the 21 biopsies of multiparas containing muscle tissue, 20 showed muscle damage; 18 of these patients were surgically cured; the mean urine loss on cough stress test reduced from 11.3 gm to 0.7 gm. Of the 8 nulliparous patients in this group with muscle tissue in the biopsy, only the biopsies of the four oldest patients showed muscle damage; none lost urine on pre or postoperative pad testing.

CONCLUSIONS:

Muscle and connective tissue damage are linked abnormalities that together lead to pelvic floor dysfunction and incontinence. Correction of ligamentous laxity can cure incontinence, even when there is muscle weakness.

Keywords: Incontinence; Muscle damage; Midurethral sling; Tenotomy; Connective tissue; Nullipara.