Transvaginal sonography in early human pregnancy

textabstractEfforts to employ transvaginal sonography as a method to visualise the internal genitalia and their contents already date from the late 1960's, when it was used to detect the embryonic heart beat and to study the female genital tract. It was reported that embryonic cardiac activity could be detected as early as 46 days menstrual age or 32 days after ovulation, which is much earlier than by then available conventional abdominal ultrasound techniques. However, the equipment was bulky and consisted of a large device producing A-mode images. Creation of two-dimensional images was extremely difficult and soon the method was forgotten. It was only after the introduction of the grey scale technique and of realtime imaging in the mid-seventies that transvaginal sonography became feasible again. However, it took a considerable time before its value was rediscovered. This was probably due more to apprehension on behalf of the investigator than to lack of acceptance by the patient. Although the significance of the transvaginal approach was recognised in the early eighties, notably in the German speaking countries and the United States, the major breakthrough came from IVF centres where it was first employed for the puncture of follicles and later for routine monitoring of induction of follicular growth. It soon became clear that transvaginal sonography could give more detailed information in the field of early embryonic development and gynaecological disease. Recently, a host of data on the first topic has been reported. Its role in late pregnancy is mainly determined by its accuracy in diagnosing placenta praevia