Etiology distribution of abnormal uterine bleeding according to FIGO classification system: A combined study of ultrasound and histopathology.

Aim: To classify the FIGO's PALM-COEIN etiology for abnormal uterine bleeding (AUB) patients according to the ultrasound and histopathology and to evaluate the etiology prevalence distribution for AUB patients.

Methods: A total of 1065 women with AUB in the Second Hospital of Shandong University between January 2019 and March 2021. The intrauterine histopathological and ultrasound results were reviewed retrospectively.PALM-COEIN etiology classification was performed according to histopathology and ultrasound. The classification system was stratified into nine basic categories: Polyp (AUB-P), adenomyosis (AUB-A), leiomyoma (AUB-L), malignancy and hyperplasia (AUB-M), coagulopathy (AUB-C), ovulatory disorders (AUB-O), endometrium (AUB-E), Iatrogenic(AUB-I), and not classified (AUB-N). The number of cases and composition ratio were also calculated.

Results: According to the FIGO's classification system, the PALM group (656,61.60%), which were defined as structural entities that can be measured visually with ultrasound and/or histopathology. 176 (16.53%) patients were classified as AUB-P,102 (9.58%) patients were classified as AUB-A, 487(45.73%) patients were classified as AUB-L, 31 (2.91%) patients were classified as AUB-M. The COEIN group (409,38.40%), which were defined as nonstructural entities that cannot be measured by ultrasound and/or histopathology. Nobody were classified as AUB-C in our group, and 383 (35.96%) patients were classified as AUB-O, 4 (0.38%) patients were classified as AUB-E,14 (1.31%) patients were classified as AUB-I,8 (0.75%) patients were classified as AUB-N.

Conclusion: In our study, AUB-L was the most common cause, followed by AUB-O, AUB-P, AUB-A, AUB-M, AUB-I, AUB-N, and AUB-E.PALM-COEIN etiology classification system played an important role in the epidemic and management standardization of AUB patients, provided an effective communication between physicians and researchers also. Ultrasonography was the preferred examination for AUB patients, especially with structural abnormalities.