The right lower abdominal distension and pain and back waist pain and anus falling, may be due to pelvic inflammatory disease, colitis and other causes. 1. Pelvic inflammatory disease: Pelvic inflammatory disease is an infectious disease of the upper reproductive tract of women, which may be caused by pathogen infection due to poor hygiene, the typical symptom of the right lower abdominal distension and pain, when the pelvic cavity is congested and compresses the nerves, there may be a back pain and a feeling of falling in the anus. 2. Colitis: Colitis may be due to environmental factors, improper diet and other causes of inflammatory diseases of the colon, the main symptom of the right lower abdominal distension and back pain anus falling, can be diagnosed through colonoscopy, CT and other related tests. Right lower abdominal distension and lower back pain anus falling, may also be appendicitis, cystitis, ectopic pregnancy and other diseases, it is recommended that the patient as soon as possible to diagnosis and treatment, comply with the medical advice according to the cause of the symptomatic treatment, so as not to delay the condition.