PRENATAL SONOGRAPHIC FINDINGS OF TRISOMY-18 - REVIEW OF 47 CASES

Prenatal sonographic findings were reviewed in 47 consecutive fetuses with trisomy 18. One or more abnormalities, excluding choroid plexus c ysts, were found in 39 fetuses (83%), including 21 of 29 (72%) fetuses examined between 14 and 24 weeks and all 18 (100%) fetuses examined a fter 24 weeks. Abnormalities most frequently detected before 24 weeks included cystic hygromas, nuchal thickening, and meningomyelocele. Int rauterine growth retardation, cardiac defects, and an enlarged cistern a magna were detected more frequently after 24 weeks than before 24 we eks (P < 0.05). Intrauterine growth retardation was the single most co mmon abnormality, detected in 51% of all fetuses and 89% of fetuses ex amined after 24 weeks. Choroid plexus cysts were identified in 25% (12 of 47) of fetuses, including 11 of 29 (38%) fetuses seen before 24 we eks. Additional abnormalities were identified in 10 of 12 (83%) fetuse s with choroid plexus cysts; one of the two remaining fetuses showed c lenched hands and a cardiac anomaly at autopsy, and the other showed u nusually large, multiple choroid plexus cysts. Awareness of the type o f anomalies and the usual menstrual age of diagnosis in fetuses with t risomy 18 should improve patient counseling and prenatal detection of fetuses considered at risk for this disorder.