PALM-COEIN* Uterine Leiomyoma (Fibroid) Subclassification System
Leiomyoma Location Categories | Type | Specific Location in the Uterus |
Submucosal (in contact with the endometrium and/or protruding into the uterine cavity) | 0 | Pedunculated intracavitary |
1 | < 50% intramural | |
2 | ≥ 50% intramural | |
3 | Contacts endometrium, 100% intramural | |
Other: Intramural (within the myometrium); subserosal (in contact with the serosa and/or protruding into the peritoneal cavity); or other locations (eg, cervical, parasitic) | 4 | Intramural |
5 | Subserosal ≥ 50% intramural | |
6 | Subserosal < 50% intramural | |
7 | Subserosal pedunculated | |
8 | Other (specify, eg, cervical, parasitic) | |
Hybrid (in contact with both the endometrium and the serosa) | 2–5† | Image shows one example: Submucosal and subserosal, each with less than half the diameter in the endometrial and peritoneal cavities |
* PALM-COEIN is a mnemonic for the structural causes (PALM) and nonstructural (COEIN) causes of abnormal bleeding (see figure PALM-COEIN Classification System). | ||
† Hybrid leiomyomas are documented as 2 numbers separated by a hyphen. By convention, the first number refers to the relationship with the endometrium and the second number refers to the relationship to the serosa. | ||
Definitions: Endometrium = glandular lining of the uterine cavity (also referred to as the endometrial cavity); myometrium = smooth muscle layer of the uterus, located between the endometrium and serosa; serosa = thin outer lining of the uterus that faces the peritoneal (abdominal) cavity, composed of mesothelium and loose connective tissue. | ||
Adapted from Munro MG, Critchley HOD, Fraser IS; FIGO Menstrual Disorders Committee. The two FIGO systems for normal and abnormal uterine bleeding symptoms and classification of causes of abnormal uterine bleeding in the reproductive years: 2018 revisions [published correction appears in Int J Gynaecol Obstet. 2019 Feb;144(2):237]. Int J Gynaecol Obstet. 2018;143(3):393-408. doi:10.1002/ijgo.12666. | ||
