Sudden lower body bleeding in the elderly may be caused by endometrial cancer, cervical cancer, ovarian malignant tumor, urinary tract infection, trauma and so on. 1. Endometrial cancer: the most important manifestation is postmenopausal irregular vaginal bleeding, which may also be accompanied by bloody or plasma vaginal discharge, lower abdominal pain and other symptoms. Combining with medical history, clinical manifestations, ultrasonography and hysteroscopy can assist in diagnosis. 2. Cervical cancer: it can also manifest as irregular vaginal bleeding in elderly women, accompanied by watery or rice slop-like vaginal discharge, which can be clearly diagnosed by cervical cytology, colposcopy and cervical tissue biopsy. 3. Ovarian malignant tumor: it can also be manifested as sudden vaginal bleeding in the elderly, gynecological examination can touch bilateral implementation or cystic solid mass, poor mobility, mostly accompanied by peritoneal effusion, which can be combined with history, ultrasonography, magnetic resonance imaging and tumor marker to assist in the diagnosis. 4. Urinary tract infection: menopausal women with decreased estrogen level due to the decline of ovarian function may suffer from recurrent urinary tract infection, which manifests as urinary urgency, urinary pain, and even hematuria, which can be diagnosed by combining with medical history and urine sediment examination. 5. Trauma: If the perineum is damaged and bleeding is caused by straddle injuries, it is easy to diagnose with medical history. In the clinic, when the elderly suddenly bleeding from the lower body, we should go to the hospital in time, and carry out relevant examinations to clarify the cause of the disease, and active treatment.