We report a case of congenital toxoplasmosis in a twin pregnancy at 21
weeks of gestation. The complete antenatal investigation included ult
rasound examination, cordocentesis and amniocentesis. The ultrasonogra
phic evaluation showed a distinct morphological aspect confirmed by th
e fetal biological profile. The time lag between placental and fetal i
nfection, or the immunological fetal responses could explain the varyi
ng stages of the fetal disease. This is another case which early demon
strates that there may exist a distinct clinical pattern in bichorial
pregnancy with varying biological fetal responses. It underlines the i
mportance of cordocentesis in the case of maternal toxoplasma seroconv
ersion, enabling us to gather a maximum number of biological data for
complete appreciation of the fetal status. The information obtained pe
rmits a precise adaptation of the medical decision.