Colorectal cancer can be prevented by removing premalignant lesions. A good portion of colorectal premalignant lesions are located in the rectum and rectosigmoid colon. There is growing interest in less invasive tissue resection techniques, such as transanal local excision (TAE), transanal minimally invasive surgery (TAMIS), endoscopic mucosal resection (EMR), and endoscopic submucosal dissection (ESD). However, these procedures can also result in complications (e.g., perforation, bleeding, abscess, stricture, fecal incontinence, and urinary retention). This chapter aims to present methods for preventing, detecting, and managing such complications during transanal local excisions and endoluminal approaches. Intraprocedural detection of complications is significantly valuable for proper management. Endoscopic evaluation should be the first step in complication management. Endoscopic clipping is preferred for treating and preventing perforations, bleeding, and abscess formation. Electrocoagulation is an effective and useful option to prevent and manage bleeding. When endoscopic methods are insufficient, alternative interventional options or abdominal surgical procedures can be considered.