Safety and mechanism of action of noninvasive radiofrequency treatment for vaginal laxity: Histological study in the swine vaginal model.

Background: Structural changes in collagen and elastin fiber density have been previously evaluated by qualitative histological studies; however, quantitative evaluations are lacking.

Aim: To evaluate quantitative changes in collagen and elastin fibers in the vaginal wall in a porcine model after volumetric radiofrequency heating with an intravaginal applicator.

Methods: An animal model was used (domestic pig, multipara: 5.67 ± 0.94 deliveries, 3 years of age). Three pigs under general anesthesia were treated (8-minute, vaginal canal area) once per week for the course of three weeks. There were 2 follow-up evaluations at one and four weeks. Histology specimens were obtained via punch biopsy under ultrasound control. Ultrasound video measurements of the vaginal wall thickness were also obtained. Tissue samples were stained by H&E as well as stains for collagen and elastin fibers.

Results: Elastin (P < .001) and collagen (P < .01) fiber density increased after every treatment. The measured increase in fibers was highest at the one-week follow-up. Elastin accounted on average for 51.46 ± 16.86% of the tissue examined (increase of 36.8% points), while collagen accounted on average for 44.83 ± 18.92% (increase of 17.1% points). The number of synthetically active cells was increased by 16%. While vaginal wall thickness did show an increase of 1.66 mm (32%), this tendency was not statistically significant (P > .05).

Conclusion: Results suggest that volumetric heating of vaginal tissue produced quantitative improvement in the connective tissue organization in a porcine study. Neocollagenesis and neoelastogenesis were observed with an increased number of synthetically active cells.