[Towards an improved antenatal screening for cystic fibrosis]

Cystic Fibrosis is an autosomal and recessive lethal disease which affects in France one newborn in 3.000. New technologies may afford quite a cheap and efficient screening for a large set of mutations within the same assay in order to test their presence or absence. These procedures are very valuable for prenatal diagnosis for further pregnancies when couples at risk have been identified through a first affected newborn. But, for carriers or couples at risk before the birth of a first child, these antenatal screening methods remain of limited efficacy. However carrier screening would be the only way, on a public health standpoint, to decrease the disease frequency as no therapy seems to emerge till now. Recently hyperechogenic fetal bowel at routine ultrasound in the second trimester has been recognized to be associated with various deleterious conditions, especially cystic fibrosis. These observations lead praticians to investigate for parent CFTRmutations screening and subsequent prenatal diagnosis if the two parents are carriers.

Through data issued from two prospective investigations, our study aimed at the estimation of both the sensibility and efficiency of the screening for cystic fibrosis using ultrasound foetal bowel examination.

Using the frequency of the disease in the population and the number of affected fetuses within the hyperechoic sample (20 in 641 in a recent study), our analysis may lead to the conclusion that fetal echogenic bowel may concern about 0.75% of fetuses.

Orders of magnitude of the sensibility and efficiency of cystic fibrosis screening through fetal echogenic bowel are calculated and lead to the conclusion that sonographic screening might decrease the number of affected newborn more than two time less.