Malone antegrade continent enema (ACE) is a procedure in which an appendicostomy is performed to effectively control intractable fecal incontinence. In this procedure, spontaneous knotting of the enema catheter inside the cecum may occur, albeit rarely. In such a situation, the knot of the ACE catheter in the cecum could not be removed easily. Here, we aimed to report two cases of spontaneous knotting of the ACE catheter during routine ACE. Moreover, we aimed to discuss the mechanism of spontaneous knotting of the catheter during ACE, preventive methods, and methods to remove the knotted catheters.