Sonographically detected hyperechoic fetal bowel: significance and implications for pregnancy management

The clinical significance of sonographically detected hyperechoic fetal bowel has not been fully established. This report describes the natural history, pregnancy outcome, and associated features of 30 cases of prenatally diagnosed hyperechoic fetal bowel.

Fetal bowel of similar or greater echogenicity than surrounding bone was considered hyperechoic. Fetuses so diagnosed were compared with matched controls and with our general obstetric population to determine the relative frequencies of cystic fibrosis, perinatal death, fetal growth retardation, and fetal trisomies.

The incidence of hyperechoic fetal bowel during the study period was 0.2% (30 of 12,776 fetuses). Four of the 30 fetuses (13.3%) with hyperechoic bowel were found to have cystic fibrosis, as compared with one in 2200 (0.05%) in the general population. Hyperechoic fetal bowel was also associated with increased risks for perinatal death (16.7%, versus 3.8% in matched controls and 1.9% in the general obstetric population) and fetal growth retardation (23.3% versus 1.9% and 5%, respectively). One fetus with hyperechoic bowel had trisomy 18, an incidence of cytogenetic abnormalities of 3.3%. This was not significantly greater than observed in our general obstetric population (1.2%) (P > .25).

The sonographic finding of hyperechoic fetal bowel is associated with an increased risk for cystic fibrosis, perinatal death, and growth retardation. The risk of fetal trisomy in cases of isolated hyperechoic bowel appears small. When detected, hyperechoic bowel should prompt a complete and careful fetal anatomical survey, consideration of parental carrier testing for cystic fibrosis, and serial sonographic assessment of fetal growth, with cytogenetic testing reserved for cases demonstrating other structural malformations.