[Possibility of ultrasonic detection of the fetal head at the end of the 1st trimester of pregnancy].
D000033:Abortion, Threatened / Q000175:diagnosis; D000328:Adult; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods*; D014463:Ultrasonography
O vozmozhnosti ul'trazvukovogo opredeleniia golovki ploda v kontse I trimestra beremennosti.