Diagnostic ultrasound ( PDFDrive )

1352 PART IV Obstetric and Fetal Sonography
A
B
FIG. 39.20 Hyperechogenic Kidneys. Transverse (A) and longitudinal (B) scans of a 24-week fetus show increased cortical echogenicity of
both kidneys (calipers), more than expected when compared with liver (L) and increased corticomedullary differentiation. The kidneys were normal
in size, and AFV was normal. Ultrasound at 32 weeks (not shown) showed similar indings. Postnatal ultrasound (not shown) on day 8 conirmed
normal-sized kidneys with increased cortical echogenicity, and there were several tiny cortical cysts. Parents had normal kidneys. Genetic testing
for autosomal recessive polycystic kidney disease (ARPKD) and hepatocyte nuclear factor 1β (HNF1β) was negative. The child, at age 9 years, has
normal renal function. Ultrasound (not shown) showed multiple 1- to 3-mm cysts in the medulla and cortex bilaterally. No deinitive cause for the
bilateral cystic kidneys has been identiied.
HYPERECHOGENIC KIDNEYS*
ISOLATED
EXTRARENAL ANOMALIES
SMALL KIDNEYS NORMAL-SIZE KIDNEYS ENLARGED KIDNEYS
SINGLE GENE DISORDER
CHROMOSOMAL ABNORMALITY
• Obstructive
dysplasia
• Obstructive Dysplasia
• HNF1β-related
disease
• Normal variant
(normal CMD)
• ARPKD
• ADPKD
• HNF 1β-related
disease
• Bardet-Biedl syndrome
• Meckel-Gruber syndrome
• Perlman syndrome
• Simpson-Golabi-Behmel
• Trisomy 13
FIG. 39.21 Algorithm for Sonographic Evaluation of Hyperechogenic Kidneys. *No family history. Otherwise, a positive family history
suggests recurrence of the known disorder. ADPKD, Autosomal dominant polycystic kidney disease; ARPKD, autosomal recessive polycystic kidney
disease; CMD, corticomedullary differentiation; HNF1β, hepatocyte nuclear factor 1β–related disease.
by ADPKD. 87,105,106 A detailed family history and an ultrasound
examination of the parents’ kidneys are important. In ADPKD,
usually one parent has the disease, and sonography usually
establishes the diagnosis. However, new mutations associated
with ADPKD can occur. Normal AFV favors ADPKD. In ARPKD
there is usually oligohydramnios, and there may be a previously
afected sibling.
Only some of the underlying causes of hyperechogenic kidneys
can be diagnosed during the prenatal period on the basis of
family history, AFV, associated abnormalities, and genetic
analysis. 107 In many cases a deinitive diagnosis will require
postnatal investigations, including histology and DNA analysis.
he kidney size and AFV are the best predictors of perinatal
outcome. 105,106 Bilateral hyperechogenic kidneys that are normal
in size with preservation of medullary pyramids, and that are
associated with normal AFV, have a favorable outcome and may
represent a normal variant. 85,108 Although further studies are
necessary to determine speciic prognostic factors, in cases of
prenatal hyperechogenic kidneys, the parents should be counselled
that parenchymal renal disease cannot be ruled out and there
is a possibility of renal failure ater birth or in early
childhood. 109
Renal Neoplasm
Congenital mesoblastic nephroma is the most common renal
neoplasm in the fetus and newborn. 110 It is a benign hamartoma
composed of mesenchymal tissue (spindle cells), as opposed to
the epithelial tissue of Wilms tumor. Wilms tumor is a malignant
lesion that is extremely rare in the fetus. Sonographically,
mesoblastic nephroma is indistinguishable from Wilms tumor.