3. Pyelonephritis
Predisposition
Most cases similar to lower UTI causes (esp intercourse)
About 20-30:1 cystitis to PN
Female, reflux, obstruction, stones, diabetes, stasis
(congenital anomalies, diverticula), pregnancy
Clinical
Gram negatives (E coli, Proteus, Pseudomonas, etc.)
Flank pain and tenderness, fever, N/V, signs of cystitis
4. Pyelonephritis
Imaging
Usually not necessary (uncomplicated PN)
Reasons to image
Uncertain diagnosis
Severe symptoms
Atypical clinical situation
men, unresolving, children, diabetics
Role out obstruction
Evaluate source in recurrent pyelonephritis
May see incidentally
Note: imaging of PN/UTI in children whole separate
topic
21. Abscess
Etiology
PN which proceeds to tissue necrosis and
liquefaction
More likely with obstruction, diabetes (75% of all
abscesses), stone disease
Normal kidneys or superinfect pre-existing lesions
(cysts, diverticula, RCC)
Can spread to perinephric space
22. Abscess
Imaging
US
CT
Rounded, thick wall cystic
mass with debris
Rounded cystic lesion with
enhancing wall
Surrounding inflammatory
changes
Microabscesses
Small, often multiple areas
in the setting of PN
RadioGraphics 2004;24:S11-S28
24. Emphysematous Pyelonephritis
Aggressive form of PN with necrosis, vascular
compromise and air production
Rare life threatening form urologic emergency
90% diabetics (poorly controlled)
Obstruction common (must exclude)
Adults
Rare, if ever, seen in pediatrics
Clinical presentation
Fever, flank pain, lethargy, renal failure, septic shock
Usually gram negatives, esp. E. Coli
41. Xanthogranulomatous Pyelonephritis
(XGP)
Disorder immune response in
setting of chronic infection, often
with obstruction and stones (ie
pyonephrosis)
Pathophysiology
Stone leads to obstruction
Caliectasis (peripelvic fibrosis limits
pelviectasis).
Infection leads to parenchymal
destruction and replacement with
lipid laden macrophages
Treatment
nephrectomy
Radiographics. 2000;20:215-243
42. Xanthogranulomatous Pyelonephritis
(XGP)
Key points
Middle age women with longstanding
infection/stones
DM in only 10%
Triad
Nonfunction
Renal enlargement
Caliectasis with less pelviectasis, parenchymal loss
Stones (90%)
Staghorn, exploded
53. Fungal Disease
Usually immunocompromised
(DM, steroids, HIV, etc.)
Candida most common
Any portion of urinary tract
Imaging
Changes of PN, abscess
Fungus ball in collecting system
Non-stone (echogenic) filling
defect
DDX: sloughed papilla, tcc, clot
Kawashima A - Infect Dis Clin North Am - 01-JUN-2003
Figure 4a. Severe unilateral acute bacterial pyelonephritis. (a) US image demonstrates a slightly enlarged right kidney that is otherwise unremarkable, belying the advanced disease. (b) CT scan shows the enlarged kidney with global decreased uptake of contrast material and multiple small low-attenuation foci from abscess pockets, findings that prompted nephrectomy. (c) Photograph of the resected gross specimen reveals multiple intrarenal abscesses that have begun to partially coalesce. Scale is in centimeters.
Figure 3b. Acute bacterial pyelonephritis. (a) US scan shows a wedge-shaped hyperechoic focus (arrowhead) in the upper pole of the right kidney related to acute bacterial pyelonephritis. (b) Color flow US image demonstrates diminished flow through the involved area.
2 different cases of mass-like hyperechoic PN
Stone
Figure 7. Acute bacterial pyelonephritis. (7) Unenhanced CT scan from a clinically documented case of acute bacterial pyelonephritis shows asymmetric enlargement and absence of the pyramids of the right kidney (cf the preserved pyramids [arrow] in the normal left kidney). Loss of the renal pyramids is a nonspecific marker for edema, which is more typically seen in obstruction related to calculi.
Figure 8. Acute bacterial pyelonephritis. (8) Unenhanced CT scan demonstrates multiple, scattered, round and oval hyperattenuation foci within the left kidney, findings indicative of hemorrhagic acute bacterial pyelonephritis.
PN; right is 5 hours later.
Figure 11. Acute bacterial pyelonephritis caused by hematologic seeding in a patient with Staphylococcus aureus endocarditis. CT scan demonstrates peripheral low-attenuation lesions (arrowheads) that are maturing into small abscess cavities. In such cases, blood and urine cultures grow the same organism.
left column: collecting duct carcinoma
Middle column: top is urothelial carcinoma, bottom is lymphoma
Right column: infarct following trauma
US – immature abscess
Emphysematous pyelonephritis represents a severe life-threatening infection of the renal parenchyma with gas-forming bacteria. Underlying poorly controlled diabetes mellitis is present in up to 90% of patients who develop emphysematous pyelonephritis. Urinary collecting system obstruction from pathologic conditions such as stone disease, urothelial neoplasm, or sloughed papilla (31) is also commonly present. Patients present clinically with varying degrees of renal failure, lethargy, acid-base irregularities, and hyperglycemia. Rapid progression to septic shock may be seen, and emphysematous pyelonephritis carries an overall mortality rate of approximately 50% (32). Flank pain and, rarely, crepitus over the lower back or thigh may be seen at physical examination (33). E coli is the causative bacterial source in approximately 70% of cases, with Klebsiella, Candida, and Pseudomonas species isolated less frequently
Bilateral emphysematous pyelonephritis in a 72-year-old man who presented with fever, chills, and near syncope. Abdominal radiograph reveals extensive, radially oriented air within and surrounding the kidneys (black arrows). Air is also seen within the left renal collecting system (white arrows).
Emphysematous pyelonephritis in a 45-year-old woman. (a) Abdominal radiograph obtained with the patient upright demonstrates a 2-cm calcification overlying the region of the left ureteropelvic junction (arrow) and several smaller calcifications overlying the lower pole. Note also the mottled collection of gas bubbles in the region of the left lower renal pole (arrowheads) and the large air-fluid level within the upper pole (*). (b) Contrast-enhanced excretory-phase CT scan obtained at the same level as a demonstrates enlargement of the left kidney with persistent parenchymal enhancement relative to the normal right kidney. Note the air-fluid and debris level (*) within the upper pole, a finding that corresponds to the radiographic finding. A large obstructing ureteral stone (arrow) and perinephric inflammatory changes are also present. (c) Photograph of the cut gross specimen reveals diffuse parenchymal necrosis.
Emphysematous pyelonephritis in a 60-year-old diabetic man with several days’ history of nausea and general malaise. (a) Longitudinal US image of the left kidney demonstrates normal findings. (b) Longitudinal US image of the right kidney shows foci of high-amplitude echoes (long arrow) with associated posterior dirty shadowing (short arrow). (c) Corresponding contrast-enhanced CT scan obtained during the late excretory phase shows multiple parenchymal gas collections (arrows
Left: 65-year-old woman with cirrhosis and portal hypertension in the right kidney Initial transverse postcontrast CT scan shows the gas-fluid level (arrow) inside the dilated calyx. (c) Transverse postcontrast CT scan obtained at a level similar to that in b 3 weeks after medical treatment shows the disappearance of both gas and dilatation of the calyces.
Right: CT scans in a 72-year-old man with staghorn calculi in the left kidney
H
Figure 23a. Xanthogranulomatous pyelonephritis. (a) Contrast-enhanced CT scan demonstrates bilateral staghorn calculi, with distention of the right collecting system secondary to inflammatory debris. (b) US scan also shows the dilated collecting system (arrowheads) and a shadowing calculus (arrow). (c) Photograph of a cut specimen clearly depicts a complex, milky infiltrate that fills and expands the collecting system.
During primary infection, TB reaches both kidneys and forms microscopic granulomas in cortex where remains innocuous, potentially forever. However if reactivation occurs, usually in one kidney. Reactivation begins in medulla, where microabscesses form in the papilla; where they can then rupture into the calyces, spreading down the collecting system. Destruction, fibrosis, calcifications and obstruction are components of the process.
49 yo female with flank pain and fever – bilateral malakoplakia