Low back pain with abdominal and anal distension may be caused by proctitis, rectal malignant tumor, perianal abscess, chronic pelvic inflammatory disease in women and chronic prostatitis in men. 1. Rectal inflammation: proctitis can cause abdominal and anal distension with lumbosacral pain. General proctitis can be seen in the lower and middle rectal mucosa congestion, edema or ulceration, bleeding, secretion attachment. 2. Rectal malignant tumor: such as rectal cancer, etc., usually accompanied by symptoms such as acute and recurrent symptoms, purulent and bloody stools, etc. Rectal palpation can be touched with hard mass in the rectum. 3. Perianal abscess: some perianal abscesses are deeper in location, the pain will not be very obvious, and the clinical manifestation is the feeling of abdominal and anal swelling or rectal irritation. 4. Female chronic pelvic inflammatory disease: chronic inflammation of the formation of scar adhesions and pelvic congestion, often causing lower abdominal swelling, pain and lumbosacral pain. It is often aggravated by exertion, prolonged standing, after sexual intercourse, and before and after menstruation. 5. Chronic prostatitis: Chronic prostatitis can also be associated with lower abdominal swelling and pain or discomfort in the scrotum, testicles, perineum and lumbosacral area. It is recommended that if you have a lower back pain accompanied by abdominal and anal swelling, you should go to the hospital in a timely manner, improve the relevant examination, find the cause of the disease, and carry out the appropriate treatment.