Methods and devices are provided for performing translumenal (e.g., transoral and transanal) procedures. In general, the methods and devices utilize a trocar assembly or trocar end cap that can facilitate insertion of an endoscope through tissue. In one embodiment, a flexible trocar assembly is provided and includes an obturator having an inner lumen formed therethrough for receiving an endoscope therein, and a distal end that is adapted to facilitate insertion of the endoscope through tissue and that is adapted to facilitate viewing therethrough. The trocar assembly can also include a trocar sleeve that is disposable over the obturator. In use, once the trocar assembly is inserted through tissue, the trocar sleeve can function as a placeholder, allowing the endoscope and obturator to be removed. The endoscope can then be removed from within the obturator and reinserted through the trocar sleeve for use in performing various other procedures. In other embodiments, rather than using a trocar that houses the endoscope, an end cap can be removably disposed over a distal end of the endoscope. The present invention also provides methods and devices for shielding an endoscope during insertion through a body lumen, and in particular for preventing contact between the endoscope (or trocar sleeve) and the body lumen, thus preventing bacteria from being carried into a body cavity.