The sudden growth of a round bag on the vulva is considered to be related to Bartholin’s gland cysts, prolapsed cervix, and submucous fibroid tumor of the uterus. 1. Bartholin’s gland cysts: If a woman suffers from vulvovaginitis, which blocks the gland ducts and prevents the glands from discharging their fluids, Bartholin’s gland cysts will appear, and drainage of Bartholin’s gland cysts is recommended if they are large in size. 2. Prolapsed cervix: For older women, pregnancy and atrophy of pelvic floor muscles may cause the cervix, uterus, vaginal wall and other tissues to prolapse outward, which may remain in the vagina in mild cases, or prolapse outside the vaginal opening in severe cases. 3. Uterine submucous fibroid: For patients with uterine submucous fibroid, as the fibroid is connected to the uterus through its long tip, it may be detached from the cervix and stay in the vagina, and the patients may also experience discomfort such as heavy menstruation and irregular vaginal bleeding. For women who suddenly grow a round bag on the inner vagina, it is recommended that they go to the gynecology department of regular hospitals to improve ultrasound and other relevant examinations, to clarify the cause of the disease and then under the guidance of the doctor to actively treat it.