Cytologic atypias in the uterine fluid of intrauterine contraceptive device users.

A peculiar cell pattern, characterized as an atypical glandular cell cluster (AGCC), was found in the uterine fluid from women using intrauterine contraceptive devices (IUDs). This atypia can mimic adenocarcinoma. Since the atypical cells were present in much higher frequency in the uterine fluid than in the cervical mucus, it is suggested that they originated in the endometrium.