Abstract： Objective To investigate the route of minimal invasive sling procedures and evaluate their safety. Methods Tension-free vaginal tape (TVT),TVT-obturator (TVT-O) and posterior intravaginal sling (P-IVS) procedure were performed on five fresh pelvis.4% formaldehyde was used to preserve the cadavers and colored latex was injected into the vessels.An anatomic study and measurements between the trocars and related vessels or organs were carried out.Results There was no complication during all injections.The distance between TVT trocar and pubic vessels,the bladder,external lilac vessels and obturator vessels were 0.6,0.6,4.2 and 4.3 cm,respectively.Out of control of TVT trocar,the axial rotation or lateral diversion of TVT handle could injure these structures.We found during TVT-O operation,the retropubic space was not violated.The right placement of introducer was very important. When the beginning point was too deep into the anterior vaginal wall,2.2 cm proximal to urethral meatus or on a horizontal plane with a 35° angle relative to the urethral sagittal plane,the introducer would enter the retropubic space or perforate the upper posterior zone of the obturator membrane,where the obturator vessels and nerves exit the obturator canal.Based on our study,the diversion of P-IVS trocar would damage the rectum,and the pudendal vessels and nerves were relatively safe.Conclusions The TVT trocar passes the retropubic space and may injure the important vessels or organs.The route of TVT-O inside-out operation is stable and the retropubic space is not violated.The blunt design in the P-IVS trocar tips is helpful to reduce injury.