Low back pain with left lower abdominal pain should be considered as a result of lesions in the left lumbar and abdominal organs, and a CT examination of the abdomen should be performed at the hospital promptly to clarify the specific lesions. Common etiologies are as follows: 1. Urinary system diseases: firstly, consider lesions of the left kidney and adrenal gland, such as tumors of the left adrenal gland, tumors and stones of the left kidney. Secondly, consider left ureteral stones and tumors; 2. Intestinal diseases: left-sided organs include left hemi-colon, such as tumors or inflammation in the splenic region of the colon, descending colon, sigmoid colon, etc., which can cause left-sided back pain and abdominal pain; 3. Left-sided organ-related diseases: tumors can occur in the retroperitoneal organs of the left abdominal cavity, such as liposarcoma and retroperitoneal tumors.