Diagnostic ultrasound ( PDFDrive )

CHAPTER 9 The Kidney and Urinary Tract 327
acoustic shadowing, indicative of gas are seen within the collecting
system (Fig. 9.23). As with EPN, CT is oten required to identify
emphysematous pyelitis because dirty acoustic shadowing from
gas at ultrasound may obscure the exact extent of renal and
perirenal disease.
Chronic Pyelonephritis
Chronic pyelonephritis is an interstitial nephritis oten associated
with vesicoureteric relux. Relux nephropathy is believed
to cause 10% to 30% of all cases of end-stage renal disease
(ESRD) 39 (Fig. 9.24). Chronic pyelonephritis usually begins in
childhood and is more common in women. he renal changes
may be unilateral or bilateral but usually are asymmetric.
Relux into the collecting tubules occurs when the papillary
duct oriices are incompetent. his relux occurs more oten
in compound papillae, which are typically found at the poles
of the kidneys. Cortical scarring therefore tends to occur
over polar calices. here is associated papillary retraction
with caliceal clubbing. At ultrasound, a dilated blunt calix
is seen, associated with overlying cortical scar or cortical
atrophy 40 (Fig. 9.25). hese changes may be multicentric and
bilateral. If the disease is unilateral, there may be compensatory
hypertrophy of the contralateral kidney. If the disease
is multicentric, compensatory hypertrophy of normal intervening
parenchyma may create an island of normal tissue
simulating a tumor.
C
G
A
B
FIG. 9.23 Emphysematous Pyelitis. (A) Transverse sonogram of left kidney shows “clean” shadowing posterior to a renal calculus (C) and
“dirty” shadowing posterior to nondependent collecting system gas (G). (B) Conirmatory unenhanced CT image shows both a calculus and gas
within the left collecting system.
A
B
FIG. 9.24 Relux Nephropathy: Renal Transplantation Evaluation. (A) Sagittal sonogram shows marked right hydronephrosis and absence
of overlying cortex. (B) Cystogram conirms massive bilateral ureteral relux.