A case report of an abnormal trend in hCG levels in a pregnancy complicated by ovarian hyperstimulation syndrome.

•Levels of human chorionic gonadotropin are affected by the fluid dynamics in ovarian hyperstimulation syndrome.•In ovarian hyperstimulation syndrome, human chorionic gonadotropin values do not follow normal trends.•Caution is warranted before diagnosing an abnormal early pregnancy in patients with ovarian hyperstimulation syndrome.