In Vivo Aspect of the Maternal — Trophoblastic Border during the First Trimester of Gestation

Abstract

Technological advances in ultrasound diagnosis have allowed internal contact examinations. The uterus and its content can be observed with a small linear 7 MHz probe inserted in the fundus of the vagina. The gestational sac can be located in the uterus from 4.5 weeks of gestation on. The cardiac activity can be detected when the heart begins to pulse (23rd day post conception), and the uterotrophoblastic border can be observed with better definition. In a prospective study, 201 patients have undergone a vaginal ultrasonic investigation between 6 and 12 weeks of gestation. In the normal cases, the uterine blood vessels are visualized all around the uterine border of the gestational sac. Moving echos generated by the red blood cells are distinguished in the maternal vessels but never in the thickness of the trophoblastic ring. In cases of missed abortions or of blighted ova, such a movement can be detected in the trophoblastic area and communications between maternal blood vessels and the intervillous space can be observed. For performing chorionic villi sampling (C.V.S.), the catheter, the needle, or the biopsy grip must be introduced into the intervillous space. All those samplings are relatively bloodless. When using the chorionoscopic method for sampling, it is possible to demonstrate in vivo that the intervillous space, during the first trimester of gestation, is normally free of maternal blood. In contrast, in cases of missed abortions, before any clinical signs appear, a maternal blood circulation is noted in the intervillous space. We can conclude that the human placenta is not hemochorial during the first trimester.