The vaginal opening is red, swollen, itchy and painful with yellowish discharge, which is considered to be caused by bacterial vaginitis, cervicitis, trichomonas vaginitis and other factors. 1. Bacterial vaginitis: Bacterial vaginitis is mainly caused by pathogens such as Haemophilus vaginalis and Mycoplasma. Patients will have an increase in vaginal discharge, the discharge is gray-yellow or gray-white, the patient will also be accompanied by vaginal itching, burning sensation and other manifestations, so the patient will have a red, swollen, itchy and painful vaginal opening with the performance of yellowish discharge. 2. Cervicitis: Cervicitis is considered to be caused by Neisseria gonorrhea, Chlamydia trachomatis, or hormonal imbalance in the body. Patients will yellowish leukorrhea, vulvar itching or burning and other symptoms, which patients will show as the vaginal opening red, swollen, itchy and painful yellowish discharge. 3. Trichomonas vaginitis: Trichomonas vaginitis is mainly caused by Trichomonas vaginalis infection, patients will appear yellowish-white, yellowish-green, grayish-yellow leukorrhea, as well as vulvar itching, burning pain and other manifestations. Therefore, patients with trichomonas vaginitis will show up as red, swollen, itchy and painful vaginal opening with yellowish discharge. It is recommended that patients with red, swollen, itchy and yellowish discharge from the vaginal opening should consult a doctor in time, who will take appropriate measures to treat the cause of the disease.