Journal of Ultrasound in Medicine, Vol 16, Issue 2 101-105, Copyright © 1997 by American Institute of Ultrasound in Medicine
First trimester isolated fetal nuchal lucency: significance and outcome
C. S. Reynders, S. P. Pauker and B. R. Benacerraf
Department of Obstetrics and Gynecology, Massachusetts General Hospital and Harvard Medical School, Boston, USA.
In this study, we determined the outcome in cases of isolated nuchal
lucency seen sonographically in the first trimester in fetuses without
karyotypic abnormalities. We reviewed all cases of isolated localized fetal
nuchal lucency (3 mm or greater) in 9 to 14 week fetuses over a 4 year
period. Fetuses with additional sonographic abnormalities were excluded.
The width of the nuchal lucency at initial sonogram as well as findings on
subsequent scans were tabulated. Karyotypic, pathologic, and clinical
follow-up data were obtained. Of 44 fetuses with an isolated, localized
first trimester nuchal lucency, one was lost to follow-up and two were
excluded owing to pregnancy termination without karyotype or pathologic
analysis, thus resulting in 41 fetuses in our study group. Five fetuses
(12%) had abnormal karyotypes. Twenty-seven of the remaining 36 fetuses had
normal karyotypes, eight others showed no evidence of aneuploidy at birth,
and one patient underwent spontaneous abortion prior to a karyotypic
analysis. Among the 36 fetuses without evidence of aneuploidy, six had a
poor outcome: two were spontaneous abortions, one was a therapeutic
abortion of a fetus with hydrops and a pericardial effusion seen on
fetopsy; one fetus died at birth of pulmonary hypoplasia associated with
autosomal recessive polycystic kidney disease, and one fetus each had
Noonan syndrome, and Joubert syndrome. In addition, three patients
delivered their infants prematurely. Overall, 32 of 41 fetuses survived,
and two (6%) were abnormal. Excluding premature infants, 27 were normally
grown, term survivors. We conclude that other than having an increased risk
for aneuploidy, fetuses with isolated nuchal lucency are also at risk for
spontaneous miscarriage, premature delivery, and congenital anomalies
unassociated with an abnormal karyotype.
