Uterine fibroids originate in the myometrium and are divided into 3 categories according to their relationship with the myometrial wall during development: intermyometrial fibroids, subplasmic fibroids, and submucosal fibroids. 1. Interstitial myomas: Myomas are located in the myometrial wall and surrounded by the myometrium, accounting for 60%-70% of the cases. 2.Subplasma leiomyosarcoma: the leiomyosarcoma grows toward the plasma surface of uterus and protrudes on the surface of uterus, accounting for about 20% of the cases, and the surface of leiomyosarcoma is only covered by the plasma layer of uterus. When the tumor continues to grow toward the plasma membrane surface, only a tip is connected with the uterine muscle wall, and it becomes a subplasma leiomyoma with a tip. It is easily degenerated and necrosed due to insufficient blood supply. If the tip is twisted and broken, the fibroid will fall off into the abdominal or pelvic cavity, forming a free fibroid. If the leiomyoma is located in the lateral wall of the uterus and grows to the side of the uterus, it is called broad ligament leiomyoma when it protrudes between the two lobes of the broad ligament. Submucosal leiomyoma: The leiomyoma grows toward the mucosa of uterus and protrudes into the uterine cavity, covered only by the mucosal layer, accounting for 10-15%. Most of the fibroids are single and make the uterine cavity deformation and enlargement, and there is no obvious change in the shape of the uterus. Submucosal fibroids tend to form a tip and grow like a foreign body in the uterine cavity, often causing uterine contraction, and the fibroids are squeezed into the vagina through the cervix. Uterine fibroids are often multi-sexual, and various types of fibroids can occur in the same uterus, which is called multiple fibroids.