P25.18: Interest of choroid plexus at first trimester in diagnosis of spina bifida

Abstract

Spina bifida's diagnosis was suggested by maternal serology at 17 weeks of gestation at the same time than for Trisomy 21. Now that trisomy 21 marquers are searched at 1rst trimester we lost this sign. Spina bifida is due to a caudal attached spinal cord attracting the cerebellum down so than choroid plexus lost their separation by cerebellum. Recently R. Chaoui demonstrated than the forth ventricule was also compressed and became invisible with sonography. In it's movement, the rounded posterior part of choroids plexus and of the ventricule become acute, the angle between their axis parallel, and the lambda sign behind them on an axial plan, disappeared. We examined choroids plexus of every fetus during their 1rst trimester examination (500 cases) and when it was possible retroactively on 1rst trimester registred scan of fetus with spina bifida (10 cases). Feasibility to get the right plan during routine examination was good, easier than to get the plan of the BPD. As supposed the four signs of normality were present in fetus with normal spine. At contrary we couldn't find one of these normal signs on the 1st trimester registred photos with spina bifida. We recognized one or several of these sign: loss of choroids plexus and ventricule's posterior boundary, lost of the angle: they became parallel and the lambda sign were not found. Choroid plexus aspect has been modified at first trimester in all spina bifida we saw. Easy to appreciate, the rounded posterior part of ventricules and choroids plexus, their angle and the lambda sign could be complementary to the 4th ventricule lost in the detection of spina bifida at 1rst trimester examination.