A pictorial review of ultrasonography of the FIGO classification for uterine leiomyomas

Uterine leiomyomas are the most common gynecological and pelvic neoplasm, reported in up to 80 percent of women by age 50. While the majority are asymptomatic, uterine leiomyomas, depending on size, number, and location can result in bulk symptoms, abnormal uterine bleeding (AUB), infertility or recurrent pregnancy loss. Ultrasonography (USG) remains first-line for the diagnosis of leiomyomas and is the most appropriate imaging modality for the initial assessment of abnormal uterine bleeding. In an effort to standardize nomenclature and identify causes of AUB, the International Federation of Gynecology and Obstetrics (FIGO) developed a classification system based on the acronym PALM-COEIN (polyp; adenomyosis; leiomyoma; malignancy and hyperplasia; coagulopathy; ovulatory dysfunction; endometrial; iatrogenic; and not yet classified). For the L category of leiomyoma, when present, a secondary and tertiary subclassification system is described distinguishing submucosal masses from others and categorizing the relationship of the mass to the endometrium and serosa. With advancements in newer minimally to non-invasive techniques developed for the management of leiomyomas, uniform characterization, mapping, and classification of leiomyomas is necessary to decide the optimal therapeutic approach. While this classification system has recently been reviewed on MR, to our knowledge, it has not been reviewed on ultrasound in the radiology literature. We hereby present a pictorial review of USG images of all the FIGO categories of leiomyomas to provide a standard guide for radiology reporting.