There is a possibility of simultaneous multiple gastrointestinal tumors, especially colorectal tumors, and we have had several cases of such problems recently. General gastroscopy can allow these tumors to be diagnosed. However, after colonoscopy reveals colonic obstruction, how do we know if there are still problems upstream? This question is more important because it involves the development of treatment plans, such as huge polyps, or tumors, which need to be removed together with surgery at the same time, or they may need to be operated again in a short period of time. In the case of obstruction on colonoscopy, imaging tests such as enhanced CT are usually used to rule out obvious problems, and small lesions that are difficult to detect on CT can be treated postoperatively under colonoscopy. However, unexpected instances exist. In cases of incomplete intestinal obstruction, the accumulated intestinal lumen contents may obscure the tumor. Such was the case in our surgery yesterday. Mr. Yang’s preoperative examination revealed a tumor in the upper rectum, which could not be passed by the colonoscope. No other tumor was found in the preoperative CT, and no significant metastasis was seen. We performed laparoscopic rectal cancer surgery as planned. Intraoperatively, we found another tumor in the transverse colon, the mass was not large, but it had invaded the plasma membrane. Later, radical resection of both tumors was completed in one operation. So, when there is intestinal obstruction, despite preoperative imaging, laparoscopy has to be done again.