Journal of Ultrasound in Medicine, Vol 11, Issue 10 533-536, Copyright © 1992 by American Institute of Ultrasound in Medicine
The "lying down" adrenal sign: a sonographic indicator of renal agenesis or ectopia in fetuses and neonates
C. K. Hoffman, R. A. Filly and P. W. Callen
Department of Radiology, University of California, San Francisco 94143.
An inability to image the kidneys, severe oligohydramnios, and an empty
(nonvisualized) urinary bladder are the most common sonographic findings in
fetuses with renal agenesis. The same features, except for the
oligohydramnios, are seen in neonates with renal agenesis. Failure to
visualize a kidney in the usual flank location with or without
demonstration of the kidney in an ectopic location may also be a feature in
fetuses or neonates with renal ectopia. The adrenal gland has an unusual
but distinctive appearance on longitudinal sonograms in these patients.
Sonograms of 23 fetuses and six neonates referred for presumed bilateral or
unilateral renal agenesis or ectopia were reviewed retrospectively for the
presence of a flattened ("lying down") adrenal gland. At the time of the
examination, the adrenal gland was not actively sought as a part of the
fetal survey or postnatal examination but was found retrospectively in 48%
of these subjects. Although this finding has been described previously, the
emphasis was on this observation as a potentially confusing sonographic
feature. This manuscript emphasizes the characteristic appearance of the
adrenal gland which instead serves as a simple means of confirming that the
kidney did not develop in the flank. Detection of a flattened ("lying
down") adrenal gland is an observation that should be actively sought in
all fetuses and neonates with a presumed diagnosis of renal agenesis or
ectopia.
