The acronym PALM-COEIN facilitates classification, with PALM referring to structural etiologies (polyp, adenomyosis, leiomyoma, malignancy and hyperplasia), and COEIN referring to nonstructural etiologies (coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, not otherwise classified).
FIGO System 2, published in 2011, focused on classifications of AUB etiology into structural and nonstructural entities using the PALM-COEIN (polyp[s], adenomyosis, leiomyoma, malignancy, coagulopathy, ovulatory dysfunction, endometrial disorders, iatrogenic, and not yet classified) classification system.