Inclusion Criteria:  Patient whose age ≥ 18 years Patient with inactive or minimally active Crohn's disease associated with one or more complex ano-perineal fistula(s) that has not responded to at least one conventional biologic therapy Patients managed for their fistula(s) by mesenchymal stem cell injection between July 1, 2020 and July 30, 2021 at one of the participating centers Patients who understand the French language  Exclusion Criteria:  Patients under guardianship or curatorship Minor patients Pregnant women Patient deprived of liberty Patient under court protection Patients who object to the use of their data for this research Patients with a simple anal fistula Patients with anorecto-vaginal fistula Patients with anal canal stenosis that cannot be crossed by the index finger Patients who have not previously received medical treatment (biotherapy +/- immunosuppressant)