National survey of abnormal uterine bleeding according to the FIGO classification in Japan

To investigate the status of abnormal uterine bleeding (AUB) in Japan using the International Federation of Gynecology and Obstetrics (FIGO) classification (AUB system 1 and 2; PALM-COEIN) and to clarify the relationship between AUB symptoms and the diseases causing AUB.

In a nationwide study, we enrolled first-time patients who visited target facilities during two consecutive weeks from December 1, 2019 to January 31, 2020. The FIGO classification was used to investigate patients with symptoms and causative diseases of AUB. Based on the proportion of patients in the nationwide study, 373 cases were included in the detailed survey. Survey items included symptoms of AUB according to AUB system 1, examination details, and causative diseases according to the PALM-COEIN classification.

Within the study period, we encountered 61 740 first-time patients, of which 8081 (13.1%) were diagnosed with AUB. Among them, 39.9% had abnormal menstrual cycles and 56.9% had abnormal menstrual bleeding. In the survey, PALM had the highest percentage of AUB-L and COEIN had the highest percentage of AUB-O. Correspondence analysis showed that COEIN was strongly associated with abnormal menstrual cycles and PALM with abnormal menstrual bleeding.

We conducted the first nationwide survey of AUB in Japan. The FIGO classification was a useful tool for the diagnosis of AUB, with a strong correlation between symptoms of AUB by AUB system 1 and the causative disease of AUB by PALM-COEIN. Conversely, a high percentage of AUB-N and AUB-E suggests that AUB system 1 and PALM-COEIN are ambiguous as diagnostic tools.