Is colonoscopy reliable for diagnosing rectal cancer?

Is colonoscopy reliable for diagnosing colorectal cancer? Experts say: The misdiagnosis rate of colonoscopy is generally low, but it is not absolutely correct, and colonoscopy cannot replace digital examination. Pathological examination is the main way to confirm the diagnosis. "Among the missed colorectal cancers, 80% are colorectal cancers." Experts point out that colorectal cancer is one of the diseases that endanger human health. Among the malignant tumors of the digestive tract, its incidence rate is second only to gastric cancer and esophageal cancer.

The early symptoms of rectal cancer are not obvious and can be easily confused with other anal diseases, so they are often ignored. The reason why many patients delay treatment is that they do not pay enough attention to blood in the stool, mistakenly thinking it is hemorrhoids, anal fissures, etc., and go to the pharmacy to buy medicine for self-treatment. When they go to the hospital for examination when it is ineffective or the condition is serious, most of them have reached the late stage of rectal cancer. In addition, some doctors only diagnose based on the results of instrument examinations, or do not conduct further examinations when hemorrhoids are found, and are even reluctant to perform digital rectal examinations. As a result, precancerous lesions in the rectum, such as polyps and ulcers, cannot be discovered in time.
In fact, it is not difficult to diagnose rectal cancer. "Most of the colorectal cancers are rectal cancers, and 80% of the rectal cancers are in the middle and lower rectum, which can be diagnosed through digital examination." Experts said that digital anal examination is a simple, easy and non-invasive examination performed with fingers, and the results of digital examination can directly reflect the lesions in the anorectal area. Early rectal cancer lesions are generally limited to the mucosa. Doctors can touch slightly raised nodules during digital examination, and the patient may not have any symptoms at this time. Symptoms will not appear until the cancer develops further, causing secondary infection and ulceration, affecting the patency of the intestinal cavity, manifested as constipation, blood in the stool, tenesmus, abdominal pain before defecation, thin stools with mucus, and unexplained pain in the sacroiliac area. Foreign bodies of different shapes in the rectum can be touched through digital examination, such as polyp-like tumors, pedunculated and movable, or nodular masses, hard, irregular in shape, and immovable. If the finger cot is sticky with mucus, it means there is purulent secretion.