Journal of Ultrasound in Medicine, Vol 13, Issue 7 541-546, Copyright © 1994 by American Institute of Ultrasound in Medicine
The normal location of the fetal conus medullaris
M. L. Robbin, R. A. Filly and R. B. Goldstein
Department of Radiology, University of Alabama at Birmingham 35233-1924.
In vivo studies of the location of the normal conus medullaris in infancy
and childhood have been extended to the fetus utilizing sonography. This
prospective study of 33 fetuses showed that the fetal conus medullaris can
be visualized in the prone fetus as early as 19 menstrual weeks. By the
time the conus medullaris was observed sonographically, its location was
within the normal adult range, thus refuting the commonly held notion that
the conus medullaris ascends to adult levels sometime in childhood. Our
results suggest that a fetal spinal cord termination level of L2-L3 or
higher should be considered within normal limits. A termination level of L3
is indeterminate and requires neonatal evaluation. A termination level of
L3-L4 or lower is abnormal and should instigate a careful sonographic
search for associated abnormalities.
