Trials de Groof, E J, Buskens, C J, Ponsioen, C Y, Dijkgraaf, M G W, D'Haens, G R A M, Srivastava, N, van Acker, G J D, Jansen, J M, Gerhards, M F, Dijkstra, G, Lange, J F M, Witteman, B J M, Kruyt, P M, Pronk, A, van Tuyl, S A C, Bodelier, A, Crolla, R M P H, West, R L, Vrijland, W W, Consten, E C J, Brink, M A, Tuynman, J B, de Boer, N K H, Breukink, S O, Pierik, M J, Oldenburg, B, van der Meulen, A E, Bonsing, B A, Spinelli, A, Danese, S, Sacchi, M, Warusavitarne, J, Hart, A, Yassin, N A, Kennelly, R P, Cullen, G J, Winter, D C, Hawthorne, A B, Torkington, J & Bemelman, W A 2015, ' Multimodal treatment of perianal fistulas in Crohn's disease: seton versus anti-TNF versus advancement plasty (PISA): study protocol for a randomized controlled trial ', Trials, vol. 16, 366 . https://doi.org/10.1186/s13063-015-0831-x Trials [E], 16(1). BioMed Central Trials, 16. BioMed Central Ltd. Trials, 16 Trials, 16(1). BioMed Central Trials, 16(1):366. BioMed Central Ltd Trials, 16:366. BioMed Central TRIALS, 16:366. BMC