The risk of cystic fibrosis with prenatally detected echogenic bowel in an ethnically and racially diverse North American population

Abstract

Fetal echogenic bowel has been reported as a normal variant in the second trimester, and has also been associated with an adverse fetal outcome, including cystic fibrosis (CF), an autosomal recessive genetic disease. Previous studies have reported that 3.3 to 13.3 per cent of fetuses with echogenic bowel discovered during the second trimester were affected with CF. Between 1994 and 1998 our laboratory tested 159 cases with echogenic bowel detected during a routine ultrasound examination. The ethnic/racial background of cases included Caucasian, African-American, Middle Eastern, Hispanic, Ashkenazi Jewish and Asian. We identified two CF fetuses (1.3 per cent) and eight fetuses with a single identifiable CF mutation (5 per cent) within this diverse population. These data indicated that the risk of CF in a fetus with echogenic bowel in this population was less than the 3.3 to 13.3 per cent prior risk currently used in most Bayesian calculations. Furthermore, the results suggested that specific risks for couples should be calculated using data specific for their ethnic or racial background. Based on our results, we recommend either amniocentesis for fetal CF studies or CF carrier screening of both parents when fetal echogenic bowel is detected as a 1.3 per cent risk of CF is considered high enough to warrant further testing.