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.