Barium enema (double barium gas-barium colonography) is a valuable radiologic examination commonly used in clinical practice. With the rapid advancement of colonoscopy technology in recent years, the frequency of barium enema has gradually decreased in clinical practice. However, if it is used inappropriately, it may delay the diagnosis of the disease or even lead to aggravation of the disease. Borrowing from a recent patient case I will give you a popularization of when not to do colon gas barium double contrast. Recently, a patient with intestinal obstruction came to see me from out of town. He had an abnormally high serum tumor marker CEA, could not pass stool for many days, and had abdominal distension and pain. The local hospital gave decompression of the lower gastric tube. He had a local CT examination of the abdomen, but it was only a plain scan without contrast enhancement (intravenous medication), and the CT report did not show any significant abnormality. Such a CT examination could not provide much reference value for the diagnosis of tumors in the abdomen. A few days later, when the bowel obstruction improved, the local hospital gave a barium enema, which showed no obvious abnormality in the colon. The reason for doing barium enema is to consider that the old man is too weak to withstand the colonoscopy. As a result, the problem came: his abdominal CT showed abnormal thickening of the ascending colon and sudden thinning of the transverse colon. The barium enema also showed abnormal thickening of the ascending colon and sudden thinning of the transverse colon. Such a case usually suggests that there is an abnormal lesion at the junction of the thick and thin areas. Because he had a barium enema, the colon was full of barium sulfate, which would seriously interfere with the image of abdominal CT examination, and even full of messy artifacts, that is to say, after having a double barium gas-barium contrast of the colon, for many days, as long as there is a little bit of barium residue, you can’t do a CT examination, and you can’t even do a PET-CT examination. This old man serum CEA increased, serum CA199 is greater than 1200, the patient intestinal obstruction can not drink laxatives to promote the exclusion of barium sulfate, the family of the New Year’s Eve is anxious. But no one can do anything. We can only give the patient repeated enemas with our own hands, and even then, the barium in the intestines could not be completely discharged. Reluctantly do a colonoscopy put, really as I presumed, in the junction of the ascending colon and transverse colon abnormal obstruction stenosis. Consider a malignant tumor of pancreatic origin or gastric origin invading the colon causing intestinal obstruction (no way to do a CT, so I can only speculate.). (The gastric wall is severely thickened and awaiting pathology). The original science emphasized many times that advanced age is not a contraindication to surgery. Nor is advanced age a contraindication to gastroscopic colonoscopy. Never go for barium enema contrast without a clear diagnosis.