1. Cannulation of the appendiceal lumen: Colonoscopic examination under direct vision of the whole colon, ileocecal junction and terminal ileum will be performed to exclude other abnormalities first, and focus on the appendiceal orifice and the surrounding mucosa. Colonoscope attached by a transparent cap will be positioned close to the appendiceal oriﬁce. Gerlach's valve will be pushed aside using the transparent cap, a standard catheter loaded with a 0.035-inch guidewire (loop-tip or hydrophilic-tip) will be placed in the appendiceal oriﬁce. The guidewire will be probed gently to insert into the appendiceal lumen. The catheter will be then subsequently moved forward after the guidewire inserting deeply into the lumen under fluoroscopic guidance.