Transvaginal Radiofrequency Ablation in Overactive Bladder; A Cadaver Study

Objectives: To demonstrate the anatomy related to the autonomic nerve condensations that are present between the anterior vaginal wall and the proximal urethra and bladder and the effect of therapeutic ablation through the anterior vaginal wall.

Methods: We positioned two fresh female cadavers (T1 & T2) in a dorsal lithotomy position to enable easy access to the vaginal canal and lower abdomen. Each of the specimen’s anterior vaginal wall was treated, with a microneedling radiofrequency probe to a depth of 7mm (Figure 1). Preparation of the specimen included the dissection of the bladder from the adjacent organs using an abdominal and perineal approach.
A vertical incision was made in the anterior bladder wall with the anterior vaginal wall attached to the bladder and urethra. The dome of the bladder was then removed, leaving the supra-trigonal area, distal ureters, and urethra all intact and en bloc with the anterior vaginal wall. We then placed the two specimens in a 10% formalin solution. Transverse sectioning was performed just above the trigone into slices of 5mm intervals (7 from T1 and 8 from T2). We then placed the specimens in cassettes and followed routine procedures for paraffin embedding and labeling. At the level of the bladder, three zones were processed: right, middle, and left. Each zone was also divided into an anterior and posterior section. To obtain the study sections, each paraffin block was serially sectioned at equal intervals and six equidistant 5-micron slices were selected for analysis. Two of the sections from each block were stained with hematoxylin and eosin (H&E) and the other four were used for immunohistochemistry (IHC) with the S-100 protein marker stained to highlight the nerve fibers and ganglion.

Results: The anatomic correlation between the invasiveness of the needles and the various structures they penetrate are demonstrated in addition to the thermal effect created by the device. The Majority of the autonomic nerve condensations and ganglia were found at a depth of 6mm from the vaginal lumen indicating that a radiofrequency device utilized could potentially impact these nerves in patients with overactive bladder.

Conclusions: This is the first anatomic study to correlate and anatomically identify the exact location of autonomic nerve condensations as they relate to the anterior vaginal wall, proximal urethra, and sub-trigonal areas. It also shows the potential mechanism of action of transvaginal radiofrequency ablation to treat overactive bladder.