Women with pain on the left side of the sacral spine may have the following: 1, ankylosing spondylitis, ankylosing spondylitis often with pain in the lumbosacral region as the first symptom, and then the pain can gradually spread upward, often with symptoms of morning stiffness on rising. This is diagnosed by blood tests and x-rays. 2, sacroiliac arthritis, sacroiliac arthritis can appear on one side of the sacroiliac joint pain, percussion pain during physical examination, when taking x-rays, the sacroiliac joint can be found to have a narrowing of the joint space, sacroiliac joint density increased. 3, dense osteoarthritis, dense osteoarthritis is common in the sacroiliac joint, common in women after giving birth during pregnancy, can present with pain in the sacral area. In this case, when CT examination is performed, it can be found that the bone of sacroiliac joint is obviously dense and hardened. 4, tumor of sacrum, when tumor of sacrum appears, it can also appear pain on the left side of sacral vertebra, and CT and nuclear magnetic examination should be performed to further confirm the diagnosis.