genitourinary infection imaging

1. INFECTIONS AND INFLAMMATORY DISEASES OF
UROGENITAL SYSTEM
KR. PERAMASAMY

2. PYELONEPHRITIS
Contrast-enhanced CT demonstrates an enlarged left kidney with
delayed and striated nephrogram.
These imaging features are nonspecific but are compatible
with acute pyelonephritis given patient’s clinical symptoms and positive
urinalysis

3. PYELONEPHRITIS
 Pyelonephritis is the infection of the renal parenchyma
 It is the most common bacterial infection of the kidney
 Infection typically ascends from the bladder.
 On ultrasound, the classic appearance of focal pyelonephritis is a
hypoechoic mass with low-amplitude echoes that disrupts the
corticomedullary junction.
 A distinct wall is lacking.
 Mild hydronephrosis can be seen on the affected side, thought to be
due to a bacterial endotoxin causing reduced peristalsis, and should
not be confused with obstructive uropathy.

4.  CT imaging findings of pyelonephritis can be nonspecific,
and the kidneys can appear normal in up to 75% of cases.
 Additional imaging patterns include unilateral kidney
enlargement, wedge-shaped or striated regions of
decreased enhancement, and perinephric stranding.
 The urothelium may also be thickened and
hyperenhancing.
 Focal pyelonephritis (previously called focal lobar
nephronia) may mimic a renal mass.

5.  Bulky and hypoechoic Left kidney with decreased vascularity.
No evident calculus or hydronephrosis - acute pyelonephritis
 Right kidney shows normal imaging features.

6.  Bulky and edematous left kidney with mild perirenal fat stranding and
multifocal nonenhancing areas – from papilla to cortex.
 No evident urinary tract gas, calculi or hydronephrosis.
 No renal vasculature thrombosis.
 No renal abscess / extrarenal collection.
 No prostatomegaly or significant postvoid residual volume
(measured on ultrasound).
 Features are suggestive of acute pyelonephritis.

7. PYONEPHROSIS
 Pyonephrosis is the infection of an obstructed collecting
system and is colloquially referred to as “pus under
pressure.”
 Treatment is emergent relief of obstruction, either with
percutaneous nephrostomy or ureteral stent.
 • Ultrasound shows nonshadowing echogenic material
within a dilated collecting system.
 A fluid-fluid level may be present.

8.  Pelvi-calyceal system shows fluid - debris levels
with few tiny calculi. No air foci are noted

9. RENAL ABSCESS
 Renal abscess is a focal necrotic parenchymal infection with a defined
wall within the kidney that most commonly results from coalescence of
small microabscesses in the setting of acute bacterial pyelonephritis.
 An abscess may simulate a cystic renal mass.
 Urinalysis may be negative in up to 30% of the time if the infection does
not involve the collecting system.

10. USG shows fluid filled mass with distinct thick wall, which
may be multiloculaed.
Small abcess less than 3cm undergo conservative therapy
Large ones undergo percutaneous drainage.

11.  Few ill-defined wedge-shaped areas of cortical
hypoenhancement in the left kidney with minimal
perinephric stranding.
 No right hydronephrosis.
 Left renal enlargement with more extensive
areas of cortical hypoenhancement and several
coalescing cortical and subcapsular fluid
collections.
 Perinephric stranding and inflammation. Mild
thickening/enhancement of the left
ureter without hydronephrosis.

12. EMPHYSEMATOUS PYELONEPHRITIS
 Emphysematous pyelonephritis is a complication of acute
pyelonephritis characterized by replacement of renal parenchyma by
gas.
 It is caused by gas-forming organisms, most commonly E. coli.
 Emphysematous pyelonephritis is almost exclusively seen in diabetic
or immunocompromised individuals.
 Emphysematous pyelonephritis is a surgical emergency requiring
broad-spectrum antibiotics and emergent nephrectomy.
 Mortality can reach 40%.
 Ultrasound shows high-amplitude echoes in the renal parenchyma
representing gas locules with posterior dirty acoustic shadowing.

13.  Axial (left image) and coronal CT with oral contrast only
shows gas replacing the superior and lateral aspect of
the left kidney (yellow arrow).
 There is gas extending into the left ureter, best seen on
the coronal (red arrow).

14. RENAL TUBERCULOSIS
 Mycobacterium tuberculosis infection of the renal parenchyma results
from hematogenous dissemination. Active pulmonary TB is present in
approximately 10%.
 Although initial renal TB infection typically involves both kidneys,
chronic changes tend to be unilateral.
 Imaging findings are characterized by focal cavitary renal lesions with
calcification.
 In addition, scarring, papillary necrosis, and infundibular strictures can
be seen.
 End-stage renal TB produces auto nephrectomy and the characteristic
putty kidney appearance, which represents an atrophic, calcified
kidney.

15. Shrunken right kidney with extensive
amorphous calcification – putty kidney
(autonephrectomy)
The upper and lower poles of the right
kidney are largely replaced by a well-
defined hypodense lesions with small
specks of calcification, the overall contour
of the right kidney is preserved except for
some distortion seen at the upper pole.

16. XANTHOGRANULOMATOUS PYELONEPHRITIS
Contrast-enhanced CT shows a massively enlarged, poorly enhancing
right kidney with dilated and distorted calyces. Several staghorn calculi are present.
There is thickening of Zuckerkandl’s and Gerota's fascia, perinephric stranding, and
retroperitoneal adenopathy.
The partially visualized small bowel in the left hemiabdomen is dilated secondary to
ileus from perirenal inflammation.
Adenopathy
Small bowel
ileus
Zuckerland fascia
Gerota fascia

17.  Xanthogranulomatous pyelonephritis (XGP) is a chronic renal infection
due to obstructing staghorn calculi, leading to replacement of renal
parenchyma with fibrofatty inflammatory tissue.
 Proteus mirabilis and Escherichia coli are the two most common
organisms.
 The clinical presentation of XGP includes flank pain and nonspecific
constitutional symptoms, such as fever and weight loss.
 Anemia and hematuria are also common.
 XGP can be diffuse (85%) or localized.
 The localized form, also known as “tumefactive XGP,” may mimic a
renal mass.

18.  CT is the primary modality for imaging, which demonstrates fatty replacement of the
renal parenchyma, marked perinephric inflammatory stranding, and staghorn calculi.
 The bear paw sign represents the configuration of the hypoattenuating fibrofatty
masses arranged in a radial pattern, reminiscent of a bear’s paw.
 Complications include perinephric abscess and fistula formation.
 Treatment is nephrectomy.
 Primary differential considerations include acute obstructing calculus with
pyonephrosis or renal/transitional neoplasm with calcification.

19. HIV-ASSOCIATED NEPHROPATHY
 HIV virus may directly infect the kidney to produce
HIV nephropathy, most commonly resulting in
focal segmental glomerulosclerosis (FSGS).
 HIV nephropathy clinically presents with nephritic
renal failure.
 The kidneys are characteristically
echogenic.
 Enlarged echogenic kidneys
are specific for HIV nephropathy.

20. INFLAMMATORY AND INFECTIOUS URETERAL
DISEASE
 Leukoplakia (squamous metaplasia)
 Leukoplakia, also known as squamous metaplasia, is a rare urothelial
inflammatory condition named for the characteristic white patch that it
produces.
 Leukoplakia is not thought to be premalignant when the renal collecting
system is involved, although there is an association between
squamous cell carcinoma and bladder leukoplakia.
 Imaging shows a flat mass or focal thickening of the renal pelvic or
ureteral wall that may produce a characteristic corduroy appearance.

21. URETERITIS CYSTICA
 Ureteritis cystica is a benign response to chronic urinary tract
inflammation, such as chronic infection or stone disease.
 Several small subepithelial cysts can be found unilaterally in the
proximal third of the ureter and renal pelvis. Ureteritis cystica does not
have any malignant potential.
 Imaging characteristically shows multiple tiny filling defects in the
ureter.
 The same disease entity can affect the renal pelvis (called pyelitis
cystica) and bladder (called cystitis cystica).

22. Intravenous pyelogram shows multiple small nodular filling
defects along the renal pelvis (left image) and Ureter (right
image).

23. MALACOPLAKIA
 Malacoplakia (soft plaque) is a rare chronic
inflammatory granulomatous condition associated
with chronic urinary tract infection (usually
Escherichia coli) that is typically seen in middle-age
women.
 It is not premalignant.
 The bladder is the most frequently involved organ,
followed by the renal parenchyma, upper urinary
tract, and urethra.
 Imaging shows multiple flat filling defects that
characteristically involve the distal ureter and/or
bladder.

24. URETERAL TUBERCULOSIS
 • Multifocal ureteral stenoses are
suggestive of ureteral tuberculosis,
 If there is also evidence of renal
tuberculosis (parenchymal
 calcification and scarring) and/or
 bladder tuberculosis (small capacity
bladder with a thickened wall) –
THIMBLE BLADDER

25. PROSTATITIS
 Bacterial prostatitis is fairly common (prevalence of 10%) and can manifest
as acute or chronic disease.
 Fluctuating PSA levels or decreasing PSA levels with antibiotic therapy
raises suspicion for prostatitis.
 Acute bacterial prostatitis is less common and typically presents with local
(painful urination, hematuria) and systemic (fever, malaise) symptoms.
 It usually occurs in young men from intra-prostatic reflux of infected urine,
but can occur following instrumentation (e.g., biopsy).
 Chronic bacterial prostatitis usually occurs in older men with undertreated /
recurrent acute prostatitis or lower urinary tract obstruction.
 Chronic prostatitis is more indolent and presents with local symptoms only.

26.  Prostatitis can be diffuse or focal and typically occurs within the
peripheral zone.
 On MRI, regions of T2 hypointense signal and mild-moderate
diffusion restriction are due to inflammatory cellular infiltrates.
 Both prostatitis and prostate cancer show increased and early
enhancement.
 Compared to prostate cancer, chronic prostatitis shows less
diffusion restriction.
 Another type of prostatitis, granulomatous prostatitis, is usually
idiopathic and self-limited.

27. CT is the best imaging tool if abscess is
suspected and will demonstrate a diffusely
enlarged, edematous gland with
predilection for peripheral zone
involvement.
When an abscess is present it is seen as a
rim-enhancing, unilocular or multilocular,
hypodensity in the peripheral zone
Ultrasound
Focal hypoechoic region in the peripheral
zone of the gland.
Discrete fluid collection suggests abscess
formation.
Color Doppler ultrasound demonstrates
increased flow in the periphery of the
abscess.

28. MRI
The prostate will be diffusely enlarged, often with associated inflammatory
changes of periprostatic fat and of the seminal vesicles
Acute prostatitis
T1: peripheral zone iso- or hypointense to transition zone
T2: hyperintense
T1 C+ (Gd): diffusely enhancing

29. BLADDER INFECTIONS
ACUTE CYSTITIS
Most common in females due to short urethra
It is due to bacterial infection (transurethral infection)
Dysuria, frequency and suprapubic pain
USG shows thickened cobble stone bladder wall with internal echoes /
debris.
Contour irregularity seen in radiation, cyclophosphamide cystitis
Emphysemtous cystitis seen in diabetic / immunocompromised patients
due to E.COLI infection

30. THE URINARY BLADDER IS DISTENDED SHOWING ABNORMAL IRREGULAR
WALL THICKENING. THE MURAL THICKNESS IS APPROXIMATELY 7 MM
NOTE- THE NORMAL URINARY BLADDER WALL THICKNESS SHOULD
NOT EXCEED 3 MM IN THE DISTENDED STATE AND 5 MM IN THE NON-
DISTENDED STATE

31. CHRONIC CYSTITIS
 Bladder wall thickening,
 Calcifications,
 Irregularity of bladder wall associated with trabeculations
 diminished bladder wall capacity
 These are the hallmark finding in chronic cystitis

32. TB – THIMBLE BLADDER
 Thimble bladder​ is a descriptive term for extreme fibrosis and
contracture of the bladder walls, resulting in a tiny bladder.
 The term is usually used to describe changes from
advanced genitourinary tuberculosis.

33. SCHISTOSOMIASIS
 Caused by schistosoma hematobium.
 The symptoms of urinary schistosomiasis are progressive,
initially being urinary such as frequency, hematuria,
dysuria.
 Subsequently, the infection spreads and produces
granulomas, polyps, fibroids and calcifications in the
bladder wall.
 Chronic evolution can lead to the formation of malignant
tumors (cancer) of the bladder.

34.  Bladder wall is thickened with
Poypoidal bladder wall thickening
 Late stages, fibrosis occurs causing
low capacity bladder with focal/
curvilinear calcification.
 Bladder wall is thickened with thin
calcification within.

35. GONOCOCCAL URETHRITIS
The typical
urethrographic finding in
gonococcal urethral
stricture is an irregular
urethral narrowing
several centimetres
long typically involving
the anterior urethra

36. EPIDIDYMITIS
 Epididymitis is infection of the epididymis, almost always ascending
from the urinary tract.
 The classic clinical presentation of epididymitis is acute unilateral
scrotal pain.
 A key ultrasound finding of epididymitis is an enlarged epididymis with
increased color doppler flow relative to the testicle.
 An associated hydrocele may be present, which often contains low-
level echoes.
 The main differential based on clinical presentation is testicular
torsion, which would demonstrate decreased testicular blood flow.
 In contrast, epididymitis features normal testicular blood flow.

37. ultrasound of the testicle and
epididymis shows a markedly enlarged epididymis measuring 1.7 cm
Incidental note is made of an epididymal cyst (arrow).
The testicle has a normal sonographic appearance.
Transverse color Doppler of the epididymis (right image)
demonstrates markedly increased fl ow

38. EPIDIDYMO-ORCHITIS
 Epididymo-orchitis is infection which has spread from the
epididymis to the testicle.
 Epididymo-orchitis has a similar ultrasound appearance to
epididymitis, but blood flow to the testicle will also be
increased.
 Infection and secondary inflammation can cause venous
hypertension, which is a risk factor for focal testicular
ischemia.

39. Increased vascularity in the left testis and epididymis in keeping with
epididymo-orchitis.
The right testis has a normal appearance

40. FOURNIER GANGRENE
 Fournier gangrene is necrotizing fasciitis of the scrotum
and perineum, a highly morbid and surgically emergent
condition.
 Infection is usually polymicrobial.
 The key imaging finding is the presence of subcutaneous
gas, often evaluated with CT.
 The appearance on ultrasound is of multiple echogenic
foci in the subcutaneous tissues with dirty posterior
shadowing

41.  Axial unenhanced CT shows a right ischial decubitus ulcer (yellow arrows)
and soft tissue gas (better seen on bone window, right image; red arrows) in
the right perineum tracking along the lateral margin of the penile base.