Sonographic detection of echogenic amniotic fluid and its clinical significance.

It has been suggested that meconium-stained amniotic fluid can be detected in the antepartum period by means of ultrasound, based on the following findings: (1) a diffuse echogenic pattern throughout the amniotic cavity, (2) a clear contrast between the amniotic fluid and the umbilical cord, and (3) layering in the more dependent areas. Reported is a case in which a similar picture was obtained in a third trimester, high-risk pregnancy, but representing vernix instead of meconium. We are aware of six cases, including ours, of sonographic detection of echogenic amniotic fluid. The review of these cases indicates that the findings refer more often to a considerable amount of vernix rather than meconium, and it is not necessarily associated with postmaturity. If echogenic amniotic fluid is identified in an obstetrical ultrasound, we recommend: (1) rule-out meconium by amniocentesis or amnioscopy, or (2) study fetal well-being by means of nonstress test and/or biophysical profile. Thus, a false positive diagnosis of fetal distress in these cases could be easily avoided.