Hidden pain on the left side under the navel may be caused by gynecological diseases, digestive system diseases, urinary system diseases and so on. 1. Gynecological diseases: If a woman has a hidden pain in the left side of the navel, it may be caused by gynecological diseases, such as pelvic inflammatory disease, adnexitis, cervicitis, endometritis, etc., due to the stimulation of inflammation can lead to a hidden pain in the left side of the navel. 2. Digestive system diseases: if the gastrointestinal dysfunction, appendicitis, gastroenteritis and other digestive system diseases, can also lead to the left side of the navel hidden pain, may also be accompanied by varying degrees of diarrhea, indigestion and other symptoms. 3. Urinary system diseases: the left side of the navel hidden pain may also be urinary system diseases, such as stones, fluid, urinary tract infection. If the symptoms of the left side of the navel, and a long time without relief, it is recommended to go to the hospital in a timely manner to identify the cause of targeted treatment.