| Submucosal | 0 | Pedunculated intracavitary fibroid (i.e., submucosal fibroid without intramural extension) |
| 1 | Submucosal fibroid with intramural extension < 50% |
| 2 | Submucosal fibroid with intramural extension > 50% |
| Intramural | 3 | Intramural fibroid in contact with the endometrium but not extending into the uterine cavity or serous surface |
| 4 | Intramural fibroid without contact with the endome-trium and without extension into the uterine cavity or serous surface |
| Subserosal | 5 | Subserosal fibroid with intramural extension > 50% and < 50% subserosal |
| 6 | Subserosal fibroid with intramural extension < 50% and > 50% subserosal |
| 7 | Subserosal pedunculated fibroid |
| Other | 8 | Other types of fibroids (e.g., cervical, broad ligament, and parasitic fibroids) |
| Hybrid type | 2-5 | Hybrid classification used when a fibroid extends from the endometrial cavity to the serosa, composed of two numbers, separated by a hyphen, the first characterizing the relationship between the fibroid and the endometrium and the second characterizing its relationship with the serosa |
