Regenerative Endoscopy in Refractory Perianal Crohn's Disease

All participants receive a single session of autologous mechanical tSVF injection following the standardized standard operating procedure. 1. Removal of existing setons where applicable (documented in CRF 3) 2. Tumescent liposuction: harvest of 60-120 mL adipose tissue from lower abdomen or flank under tumescent anaesthesia (Klein formula) 3. Mechanical emulsification and filtration to obtain tSVF using the specified device and Standard operating procedure - minimum acceptable yield ≥5 mL 4. Intraoperative tSVF product quality check: Gram stain from final product; viability assessment by Trypan Blue exclusion where feasible; flow cytometry sample aliquot (sub-study, see Appendix D) 5. Fistula preparation: examination under anaesthesia (EUA), curettage of tract, and identification/closure of internal opening 6. tSVF injection (6-12 mL total): circumferentially around internal opening region in 0.1-0.3 mL blebs; along tract length avoiding sphincter penetration 7. Standard postoperative wound care and antibiotics per unit protocol