Hidden pain on the left side of the stomach needs attention to be vigilant for ulcerative colitis, urinary tract infections, chronic gastric diseases, pancreatic diseases and so on. 1. Ulcerative colitis: if the patient suffers from ulcerative colitis, there may be hidden pain on the left side of the abdomen, diarrhea, stool viscosity with pus and blood and other symptoms. 2. Urinary tract infections: such as acute cystitis, left-sided ureteritis, etc., because of the stimulation of inflammation may lead to the left side of the abdomen hidden pain, and there may also be urinary urgency, urinary frequency, urination pain and other symptoms. 3. Chronic gastric diseases: such as gastric ulcer, erosive gastritis, duodenal ulcer, etc., may cause hidden pain on the left side of the stomach, but also may have nausea, belching, acid reflux and other symptoms. 4. Pancreatic diseases: For example, pancreatitis, pancreatic cancer and other diseases, the patient may appear in the left side of the abdomen pain, nausea, loss of weight, loss of appetite and other symptoms. If the left side of the stomach hidden pain, in addition to the appeal of the cause, there are cardiovascular disease, spleen disease, digestive tract tumors and other causes, it is recommended that timely medical care, improve the relevant examination, a clear diagnosis, the cause of the treatment, so as not to miss the condition.