title: Instrument for measuring the available diameter of the internal cervical os.
mesh_terms: D000028:Abortion, Induced / Q000009:adverse effects; D002584:Cervix Uteri / Q000033:anatomy & histology* / Q000502:physiology; D004106:Dilatation; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006176:Gynecology / Q000295:instrumentation*; D006801:Humans; D009774:Obstetrics / Q000295:instrumentation*; D011247:Pregnancy; D002581:Uterine Cervical Incompetence / Q000175:diagnosis* / Q000209:etiology