Diagnostic ultrasound ( PDFDrive )

326 PART II Abdominal and Pelvic Sonography
A
B
FIG. 9.21 Pyonephrosis. (A) Sagittal ultrasound of an older male with Proteus mirabilis sepsis shows a deformed, chronically hydronephrotic
kidney, with layering collecting system echoes. (B) Corresponding noncontrast-enhanced CT shows a large right hydronephrotic sac and perinephric
iniltration. Clinical history and imaging indings prompted successful, emergent drainage.
A
B
FIG. 9.22 Emphysematous Pyelonephritis Type 1 (EPN1). (A) Sagittal sonogram of right renal fossa shows extensive shadowing gas occupying
most of the right kidney. (B) Corresponding noncontrast-enhanced CT demonstrates diffuse parenchymal destruction of the right kidney with
extensive mottled gas. Nephrectomy was eventually performed in this septic, diabetic patient. Caution must be exercised to avoid missing EPN1
altogether on ultrasound. Failure to see a kidney in a septic patient should prompt alternative cross-sectional imaging.
characterized as renal or perirenal luid collections, with bubbly
or loculated gas or with gas in the collecting system. Mortality
rates for EPN1 and EPN2 were 69% and 18%, respectively. he
authors postulated that the diferent clinical outcomes of EPN1
and EPN2 result from the patient’s immune status and the vascular
supply of the afected kidney. Emergency nephrectomy is the
treatment of choice for EPN1, whereas percutaneous drainage
is recommended for EPN2. CT is the preferred method to image
patients with EPN, to determine the location and extent of renal
and perirenal gas. Sonographic evaluation of EPN1 or EPN2
may be diicult because dirty shadowing from parenchymal gas
will obscure deeper structures; shadowing might also prompt
an erroneous interpretation of renal calculi or bowel gas 38 (Fig.
9.22).
Emphysematous Pyelitis
Emphysematous pyelitis refers to gas localized within the urinary
collecting system. 34 his disease entity is seen most oten in
women with diabetes or obstructing stone disease; a mortality
rate of 20% has been reported. It is important to exclude iatrogenic
causes of gas within the collecting system. At ultrasound,
nondependent linear echogenic lines with dirty distal posterior