Comparisons of Anterior Vaginal Wall Indentation Parameters in Age-Matched Control and Prolapse Patients Using an Operator Independent Artificial Finger

GOAL: To compare reaction forces of the human anterior vaginal wall in control (C) and prolapsed (P) women in response to pressure applied at different angles of indentation through an automated artificial finger equipped with a distal sensor. METHODS: Following IRB approval, a tripod-mounted, artificial finger equipped with a calibrated, piezoresistive sensor at its tip and automated by NI LabView 2015 software for motion control via an actuator was used to create anterior vaginal wall deformations at 10, 15 and 20 degree angles. Age-matched women in the C and P groups were compared. All measurements were performed in the supine position in the operating room, with patients under general anesthesia prior to the start of the operation and after the bladder was drained. Each deformation included a 1 second upwards indentation, a 1 second maintenance "hold", and a 1 second return of the fingertip to the baseline. Measurements were done in triplicate with a 3 second interval between each deformation sequence. Real-time voltages, equivalent to reaction forces sensed by the sensor during each indentation, were modeled as function of motion profiles and analyzed in Excel. The motion profile of each indentation was used to calculate baseline voltage, amplitude change over the 1 second interval of upwards indentation, and slope of the upwards indentation curve in its median 0.5 second range. RESULTS: Five women of similar age group (mean 64, 51-73) were studied in each group. A significant difference was observed between all degrees of indentation in baseline voltage in P and C groups (p<0.05). At 10 and 20 degrees of indentation, there was a significant difference in amplitude change between P and C groups, while there was a significant difference in slope of indentation at 15 degrees between P and C groups. CONCLUSION: The biomechanical properties of the human anterior vaginal wall can be objectively determined by a new device resembling the human finger. This mounted, free-standing artificial finger can apply a predictable and reproducible deformation to the anterior vaginal wall to compare the indentation properties of vaginal tissue in prolapsed and non-prolapsed conditions.