Fetal hyperechogenic bowel and Down's syndrome.

Hyperechogenic bowel was identified among 55 of 6781 (0.81%) fetuses prior to second-trimester genetic amniocentesis. Trisomy 21 was found in eight of the 55 (14.5%) fetuses identified with hyperechogenic bowel compared to 60 of 6726 (0.89%) fetuses with normal bowel echogenicity (p < 0.001). Hyperechogenic bowel carried a 16-fold greater risk for Down's syndrome than normal bowel echogenicity (relative risk 16.8, 95% confidence intervals 8.2-32.5). Chromosome abnormalities other than trisomy 21 were found in four additional fetuses with hyperechogenic bowel (two triploid and one each with 47,XXX; 45,X/47,XXX mosaicisim). Combining these four cases with the eight fetuses having trisomy 21, 21.8% (12 of 55) of fetuses with hyperechogenic bowel proved to have a chromosome abnormality. We conclude that hyperechogenic bowel is associated with chromosome abnormalities, particularly Down's syndrome, when detected during the second trimester. Copyright 1993 International Society of Ultrasound in Obstetrics and Gynecology