PROGNOSTIC IMPLICATIONS OF FETAL ECHOGENIC BOWEL

Background An increased frequency of hyperechogenic bowel on ultrasoun d has been reported in fetuses with cystic fibrosis (CF) and trisomy-2 1. However, the diagnostic application of this observation has been ha mpered by the absence of a means of measuring echogenicity. Methods We devised an ultrasonic grading system in which echogenicity was quanti fied by linear gain reduction and comparison with fetal iliac crest. F rom 7400 second-trimester ultrasound referrals, 145 patients were iden tified as having a fetus with abnormally echogenic bowel. They were of fered genetic counselling, parental and (if appropriate) CF carrier te sting, and amniocentesis for karyotype and CF status if parents were i nformative. Follow-up was to 4 months of age. Findings Of 40 fetuses w ith mild increase in bowel sonodensity (grade 1), none had CF or aneup loidy. Of 81 patients identified with a moderate increase (grade 2), 2 had trisomy 21 and 2 had CF. And of 24 pregnancies with a pronounced increase (grade 3), 5 had CF and 6 had trisomy-21. Interpretation Pare ntal CF carrier testing and amniocentesis to identify aneuploidy or fe tal CF status has a high positive ascertainment rate in fetuses with e chogenic bowel grades 2 and 3.