The anatomy of midurethral slings and dynamics of neurovascular injury.

The aim of this study was to investigate the course of midurethral slings using tension-free vaginal tape. The TVT procedure was performed on six fresh pelves, measurements were obtained, and the structures were cross-referenced in 16 embalmed pelves. The midurethral sling enters the suburethral tissue 2.2-3 cm caudad to the internal urethral meatus, pierces the paraurethral musculature and vascular plexus, and exits 2+/-0.5 cm from the midline lateral to the point of insertion of the arcus tendineus fasciae pelvis. On the pubic tubercle the sling is 4+/-0.5 cm, 4+/-1 cm and 6+/-1 cm from the accessory obturator, the inferior epigastric and the external iliac vessels, respectively. The critical angle of error resulting in the external iliac vessel injury is 7-15 degrees. A current knowledge of pelvic anatomy may help the surgeon avoid the neural and vascular structures that are in the path of the sling.