ABSTRACT
The first trim ester is referred to as early pregnancy and comprehends the lapse of time between conception and the end of the 12th week of gestation with embryo nic implantation and organogenesis. A pathological early gestation takes place when the embryo does not correctly implant in the cavity of the uterus (extrauterine pregnancy), when th ere is no growth of the embryo (missed abortion) or the embryo is not developing at all (blighted ovum) and sooner or later there is a miscarriage. A special case of missed abortion is the so called vanishing twin, when during a twin gestation, one embryo stops to grow. Rarely gestational trophoblastic disorders as the complete mole (without fetal tissue) or incomplete mole (with fetal tissue) and the invasive mole as villous trophoblastic diseases as well as the non-villous trophoblastic diseases with the extremely rare chorioniccarcinoma are detected.
