Discomfort in the left back generally has the following common clinical causes: i. Acute pancreatitis, the pancreas is located in the left back of the body, if inflammation of the pancreas occurs, it will cause pain and discomfort in the left back. As pancreatic exudation and infection worsen, the symptoms of pain in the left back of the patient will become more and more obvious, and may even spread to the pain in the whole lower back. Second, the left kidney giant cyst, the left kidney cyst has compression symptoms on the kidney and ureter and other surrounding organs, which will cause poor urinary excretion, thus causing distension and discomfort in the left back of the patient. Third, left ureteral stone. Small stones embedded in the ureter will cause spasmodic pain in the ureter, and if the blockage is serious, the patient will have dilated ureter and fluid in the renal pelvis, which will cause pain and discomfort in the left back of the patient.