Left-sided abdominal pain to do colonoscopy normal, may be irritable bowel syndrome, urinary stones and other diseases, women may also be caused by adnexitis. 1. Irritable bowel syndrome: belongs to the dysfunctional syndrome, the general patient may appear long-term left-sided abdominal pain symptoms, and enteroscopy and other related projects, the examination is normal, but at the same time will be accompanied by constipation, diarrhea and other symptoms. 2. Urinary stones: for patients with left urinary stones, there may be symptoms of hidden pain in the left side of the abdomen, but in this case, it is necessary to carry out ultrasound of the urinary system, urography, CT and other related projects can be a clear diagnosis, enteroscopy can not be detected, so enteroscopy performed as normal. 3. Adnexitis: for women may also be due to adnexitis, left salpingitis can also cause hidden pain in the left side of the abdomen, but colonoscopy can not see the adnexa, so the adnexa examination appears normal. The causes of left-sided abdominal pain are more reasons, in addition to colonoscopy, but also need to carry out routine blood, stool culture, urinary system ultrasound, uterine ultrasound and other related projects, according to the results of the examination and the patient’s other symptoms, a comprehensive and clear cause of the cause of the disease, under the guidance of the doctor for the cause of the treatment.