Hidden pain in the left side of the abdomen can be seen in female adnexitis, left kidney stone, colon cancer, urinary tract infection and other diseases. 1. Adnexitis: If female patients have vague pain in the left side of the abdomen, it may be related to adnexitis. Inflammation can stimulate the nerves and lead to vague pain on the left side of the abdomen. In addition to pain, it can also be accompanied by increased vaginal discharge, lumbago, abdominal mass and other symptoms. 2. Left side kidney stone: patients with left side kidney stone may have vague pain in the left side of the abdomen due to the stimulation of the nerves on the surface of the renal pelvis caused by the displacement of the stone. Besides pain, it may be accompanied by hematuria, abdominal distension, nausea and other symptoms. 3. Colon cancer: patients with colon cancer may also have vague pain in the left side of abdomen, which is mostly caused by the tumor compressing and invading nerves. Besides pain, it may be accompanied by abdominal distension, blood in stool, peritonitis, peritoneal effusion and so on. 4. Urinary tract infection: it may cause left side abdominal pain, but not all patients will have this situation. Urinary tract infection itself may be pyelonephritis and ureteral inflammation, if it occurs on the left side, it will cause the symptoms of left-sided abdominal pain. Causing vague pain in the left side of the lower abdomen can also be seen in inflammation of the intestines and other diseases, it is recommended to consult a doctor in time to clarify the cause of the disease and early treatment.