Hidden pain under the left quarter rib area may be caused by gastric ulcer, spleen injury, left hemicolonitis, etc. 1. Gastric ulcer: the stomach is located in the left upper abdomen under the raphe, when gastric ulcer occurs in the stomach, gastric acid erodes the gastric mucosa, causing damage to the gastric mucosa, resulting in gastric discomfort, which is projected to the surface of the body as a vague pain in the lower left costal region, and eating can stimulate the secretion of gastric acid to increase, resulting in aggravation of the pain. 2. Spleen injury: the spleen is located in the left quadrilateral rib area, which is a brittle organ. When the left upper abdomen is injured by contusion, impact and other injuries, the spleen is prone to rupture and hemorrhage, and the formation of hematoma in the local area can cause vague pain under the left quadrilateral rib area. 3. Left hemicolonitis: the upper part of the left hemicolon is also located under the left quarter rib area, due to bacterial, viral and other microbial infections, inflammation stimulation of the intestinal mucosa inflammatory injury, which can trigger the feeling of vague pain under the left quarter rib area. The cause of vague pain under the left quarter rib area is also associated with kidney stones, angina, tumors and other causes, the patient should go to the hospital in time, improve the examination, clarify the cause of the disease and then timely treatment.