You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Investigation of choice of depth of penetration and nodal stage in rectal carcinoma is and explain in detail?
A colonoscopy is required if possible in all patients to exclude a synchronous tumour, be it an adenoma or a carcinoma. If a proximal adenoma is found, it can be conveniently snared and removed the colonoscope. If a synchronous carcinoma is present, the operative strategy will need changing. If a full colonoscopy is not possible, a CT colonography or barium enema can be performed Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1232