National survey of primary amenorrhea and relevant conditions in Japan

Aim In Japan, most of the patients with primary amenorrhea or related conditions, such as delayed menarche, are diagnosed by pediatricians or gynecologists; accordingly, the number of the patients and the ratio of the causes were unclear. To clarify them, we conducted a nationwide survey in both the departments for the first time. Methods We sent a questionnaire about the patients with chief complaint of no menarche whose first visit was from January 2015 to December 2017, to 596 training institutions for specialist physicians of the Japan Society of Obstetrics and Gynecology and 152 facilities to which councilors of the Japanese Society for Pediatric Endocrinology belong. Results We received replies from 283 (37.8%) institutions. During the 3 years, 1043 patients first visited pediatrics or gynecology for no menarche. In 303 patients under 16 years old at the first visit, 177 (58.4%) patients had menarche by the age of 16. Of them, 41 (13.5%) patients had menarche spontaneously. Among 308 patients aged 16 to 17 at the first visit, 216 patients were 18 years or older at the survey. Of them, 124 (57.4%) patients had menarche by the age of 18, and 21 (9.7%) of them had menarche spontaneously. The causes of amenorrhea were detected in 462 patients. Abnormal karyotype including Turner syndrome was the most common at 122 (26.4%), followed by Mullerian agenesis at 73 (15.8%). Conclusions The first national survey revealed the number and causes of primary amenorrhea and related conditions. This report will provide better information for clinicians.