**3.1 Classification**

There are many fibroid classifications in the literature. Many issues have been considered among these, including the leiomyoma's relationship with the endometrium and the serosa, their location within the uterus (upper segment, lower segment, cervix, anterior, posterior, lateral), the size and the number of lesions [15]. The primary classification system reflects only the presence of one or more leiomyomas; In the secondary system, focus on differentiation of fibroids that involve the endometrial cavity (submucosal or SM) from others is the main point because it's known that submucosal myomas are those that most likely contribute to the genesis of abnormal uterine bleeding [16].

The international Federation of Gynecology and Obstetrics (FIGO) classification system for abnormal uterine bleeding [17] is intended to help better categorize the causes of bleeding and treatment planning [18]. They describe eight types of fibroids as well as a hybrid presentation (a myoma that fulfills criteria for 2 different types among the classification). This classification offers a more representative "map" of fibroid distribution [19] and also includes the categorization of intramural and subserosal leiomyomas [20].

A myoma FIGO type 0 is pedunculated and 100% intracavitary, type 1 is submucosal with less than 50% intramural extension; type 2 is submucosal with 50% or more intramural extension, type 3 is intramural but in contact with the endometrium without disrupting it, type 4 is 100% intramural not in contact with the endometrium, type 5 is subserosal with 50% or more intramural extension, type 6 is subserosal with less than 50% intramural extension, type 7 is subserosal and pedunculated, type 8 are other types of myomas including cervical and parasitic fibroids. Hybrid fibroids are given two numbers, the first number refers to the relationship with the endometrium and the other with the serosa, e.g. 2–5 has submucosal and subserosal component (**Figure 2**) [19].

**Figure 2.** *Leimyoma subclassification system (FIGO). Image taken and edited from ref. [20].*
