Defining the histopathological changes induced by nonablative radiofrequency treatment of faecal incontinence - a blinded assessment in an animal model

Aim Nonablative radiofrequency (RF) sphincter remodelling has been used to treat gastro‐oesophageal reflux disease (GERD) and faecal incontinence (FI). Its mechanism of action is unclear. We aimed to investigate the histomorphological and pathophysiological changes to the internal and external anal sphincter (IAS and EAS) following RF remodelling. Method An experimental FI model was created in 12 female pigs: eight underwent RF 6 weeks following induction of FI (FI+RF) and four were untreated (UFI). Four animals served as controls (CG). Two blinded pathologists examined all haematoxylin and eosin and trichrome stained slides. Results Compared with the UFI group, histological examination of the IAS in the FI+RF group demonstrated an increased smooth muscle (SM)/connective tissue ratio (77.2 vs 68.1%, P