[Intravaginal echography at the beginning of pregnancy]

Endocavity ultrasound during the first three months of pregnancy provides greater detail in a number of obstetrical fields. In most cases, endocavitary ultrasound is not simply a way of "gaining time" in comparison with conventional transabdominal ultrasound (time saved estimated to be one week). In some cases it is also offers a definite "extra". Two areas of interest are focussed on particularly by the authors: 1) the fetal appendages (vitelline sac, membranes, extra-embryonic coelom, trophoblast) which may be detected or revealed in greater detail by endovaginal ultrasound, make it possible to get a picture of the embryology of the fetus and of the prognosis of the pregnancy. The combination of color coded Doppler corroborates this new approach to the fetus; 2) the developments of this "sono-embryology" makes it possible to identify certain fetal malformations at a very early stage (neuro-medullary, parietal malformations...). However, interpreting the morphology of the fetus examined during the first three months must remain prudent and is no substitute for the morphological ultrasound scan carried out at about four and one half months of pregnancy.