WONDER-01: immediate necrosectomy vs. drainage-oriented step-up approach after endoscopic ultrasound-guided drainage of walled-off necrosis—study protocol for a multicentre randomised controlled trial. - Sato, Tatsuya; Saito, Tomotaka; Takenaka, Mamoru; Iwashita, Takuji; Shiomi, Hideyuki; Fujisawa, Toshio; Hayashi, Nobuhiko; Iwata, Keisuke; Maruta, Akinori; Mukai, Tsuyoshi; Masuda, Atsuhiro; Matsubara, Saburo; et al. (Trials, 2023)