Pain in the left upper abdomen by the ribs may be caused by trauma, costochondritis, pleurisy, gastrointestinal diseases, etc. 1. Trauma: If there is a bump or obvious trauma to the rib cage side of the left upper abdomen, it will lead to pain in the area. 2. Costochondritis: Costochondritis is mainly a sterile inflammation caused by acute and chronic injuries, leading to pain along the rib cage in the left upper abdomen. It usually manifests as increased pain when taking a deep breath or lying on the left side. 3. Pleurisy: Pleurisy refers to the inflammation of the pleura caused by the stimulation of the pleura by pathogenic factors, leading to pain in the left upper abdomen along the rib cage. The main symptoms are fever, cough, sputum, etc., and even severe pain when there is a limitation of deep breathing. 4. Gastrointestinal diseases: for example, gastric ulcer, acute gastritis, gastric cancer and so on. In addition to pain in the left upper abdomen along the rib cage, such diseases are usually accompanied by specific gastrointestinal symptoms, such as acid reflux and hiccups. It is recommended that patients with pain in the left upper abdomen by the ribs should go to the hospital in time to clarify the cause of the disease and follow the doctor’s instructions for treatment.