Diagnostic ultrasound ( PDFDrive )

1906 PART V Pediatric Sonography
in ipsilateral hydroureteronephrosis. he renal parenchyma may
be thin and the echogenicity may be abnormally increased as a
result of long-standing relux or obstructive nephropathy. Many
infants with posterior urethral valves have secondary renal
dysplasia, manifesting on sonography as brightly echogenic
kidneys usually devoid of corticomedullary diferentiation and
oten containing tiny cysts. 198 he appearance of the renal
Ureter
Bladder
Urethra
FIG. 54.57 Posterior Urethral Valves in Newborn Boy. Midline
sagittal scan shows irregularly thickened bladder wall (caused by obstruction),
massively dilated posterior urethra, and moderately dilated tortuous
distal ureter. Arrows show the serosal surface of the bladder wall. (With
permission from Rosenberg H. Sonography of pediatric urinary tract
abnormalities. Part I. Am Urol Assoc Weekly Update Series. 1986;35:
1-8. 231 )
parenchyma has predictive value in infants with posterior urethral
valves with regard to potential renal function. 199
he prune-belly syndrome (abdominal muscle deiciency or
Eagle-Barrett syndrome) is another common cause of urinary
tract obstruction in infant boys. he syndrome is composed of
a triad of absent abdominal musculature, bilateral hydroureteronephrosis,
and cryptorchidism. here are three forms of urinary
tract abnormality. In the most severe form, urethral atresia and
renal dysplasia are present; these children have a very poor
prognosis and typically die in infancy. Associated congenital
anomalies are frequent and include intestinal malrotation or
atresia, imperforate anus, Hirschsprung disease, congenital heart
defects, skeletal anomalies, and cystic adenomatoid malformation
of the lung. In the less severe form of urinary tract abnormality,
the bladder is large and atonic, and there is bilateral hydroureteronephrosis,
impaired renal function, and no urethral obstruction.
he changes are thought to be caused by a neurogenic
dysfunction rather than a mechanical obstruction. here are
usually no associated congenital anomalies, and these infants
have a better prognosis. 200 In the mildest type of prune-belly
syndrome, the urinary tract is only mildly afected.
Other uncommon forms of bladder outlet obstruction include
anterior urethral valves, urethral duplication, congenital urethral
stricture, anterior urethral diverticulum, posterior urethral polyp 201
(Fig. 54.58), and stones 202 (Fig. 54.59). Rarely, a giant bladder
diverticulum many descend below the bladder neck and lead to
bladder outlet obstruction. 203 Voiding cystourethrography
(VCUG), in addition to sonography, is usually necessary to identify
these urethral obstructions.
The Ureter
he ureters cannot be visualized on ultrasound unless they are
dilated. Real-time sonography can sometimes diferentiate between
B
A
B
FIG. 54.58 Congenital Urethral Polyp That Caused Prenatal Hydroureteronephrosis in Newborn Boy. (A) Voiding cystourethrography
demonstrates an oval, polypoid mass in the posterior urethra (solid arrow) and posterior bladder wall thickening (open arrows). (B) Sagittal sonogram
of the bladder (B) 4 months later shows a solid polypoid mass (arrow) protruding from the bladder neck into the bladder lumen. (With permission
from Caro PA, Rosenberg HK, Snyder 3rd HM. Congenital urethral polyp. AJR Am J Roentgenol. 1986;147[5]:1041-1042. 201 )