Purpose: The treatment of high transsphincteric fistula is a complex procedure, which may be associated with the risk of recurrence and fecal incontinence. In this study, we used an animal model to compare different types of sphincter-preserving treatments for transsphincteric fistula.
Methods: Sixteen female New Zealand rabbits, weighing 2.8-4.8 kg underwent a surgical creation of high transsphincteric fistula. After 6 weeks, magnetic resonance imaging (MRI) was performed in order to confirm fistula formation and measure the fistula diameter. The rabbits were divided into three groups. Group 1 received no plug treatment (control). Autologous dermal graft and acellular dermal matrix were used as a plug in groups 2 and 3, respectively. Five weeks after treatment, fistula tract healing was determined by measuring the largest fistula diameter with MRI. All rabbits were euthanized and the anorectum excised en bloc for histopathological examination.
Results: According to the MRI findings, all groups showed significant healing after the treatment (p < 0.05). The healing rate of fistula diameters after treatment was 40, 66, and 29% in the control, dermal graft, and acellular dermal matrix groups, respectively. In terms of negative healing parameters such as neutrophil, eosinophil, lymphocyte, and plasmocyte accumulation, dermal graft and acellular dermal matrix groups showed significantly lower results than those in the control group (p < 0.05).
Conclusion: According to MRI and histopathological results, fistula tract curettage and fistula orifice closure improved transsphincteric anal fistula healing. Additionally, in this study, plug treatment favoring autologous dermal graft resulted in better healing.
Keywords: Acellular dermal matrix; Autologous dermal graft; Fistula curettage; Transphincteric anal fistula.