Urine leaks and urinomas: causes, diagnosis and imaging
features.
Poster No.:
C-1087
Congress:
ECR 2011
Type:
Educational Exhibit
Authors:
B. Ginanni, F. Bianchi, F. Cerri, G. Caproni, A. Bulleri, N.
Armillotta, D. Caramella, C. Bartolozzi; Pisa/IT
Keywords:
Abscess, Cystography / Uretrography, Ultrasound, Plain
radiographic studies, CT, Urinary Tract / Bladder, Kidney,
Abdomen
DOI:
10.1594/ecr2011/C-1087
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Page 1 of 45
Learning objectives
•
•
•
To illustrate urine leaks and urinomas of the kidney, ureter, urinary
bladder, and urethra
To describe imaging findings of urine extravasations
To discuss their complications with respect to causes, diagnosis and
imaging features
Background
Urine leaks result from disruption of the urinary collecting system at any level from
the calix to the urethra [1].
Extravasating urine is collected near the urinary tract and may manifest as:
1.
2.
3.
free fluid, also called urinary ascites, if the fascial planes are disrupted (less
frequently in renal tears);
acute spread to local tissues;
encapsulated fluid collection surrounding by a fibrous capsule resulting from
chronic tissue irritation by urine (urinoma) (fig. 1) [2, 3, 4].
The development of an urinoma requires, as well as the rupture of the collecting system,
a maintained renal function [3].
Urine leaks and urinoma have a variety of causes, mainly depending on their origin from
urinary collecting system (fig. 2).
More frequently they are caused by blunt or penetrating trauma, iatrogenic injury, or
transmitted back pressure caused by a downstream obstruction [2].
Urine leaks may be occult initially; only malaise, vague abdominal pain, weight loss and
palpable mass can be present (fig. 3) [2].
Early diagnosis is important:
•
to avoid complications such abscess, electrolyte imbalances,
hydronephrosis and paralytic ileus;
Page 2 of 45
•
for a successful treatment.
Moreover, urinomas can be misdiagnosed as cystic masses, or pelvic hematomas or
abscesses and a delayed diagnosis may lead to a loss of renal function [2].
According to this view, diagnostic imaging play a crucial role in promptly identifying
these leaks and in determining cause, extent and during follow-up.
Images for this section:
Fig. 1: Appearences of urinary leaks.
Page 3 of 45
Fig. 2: Main causes of urinary collecting system tears in relation to their origin.
Page 4 of 45
Fig. 3: Clinical and laboratory findings in urinary leaks.
Page 5 of 45
Imaging findings OR Procedure details
# RENAL LEAKS AND URINOMAS
- Causes:
•
blunt or penetrating renal trauma (renal laceration or renal vascular pedicle
injury)
•
urinary obstruction (ureteral stone, abdominal or pelvic masses,
retroperitoneal fibrosis)
•
iatrogenic injury during percutaneous or surgical procedures
Causes of renal leaks
- Imaging:
Ultrasound (US) examination is the first diagnostic approach in the suspicious of renal
tears.
It usually demonstrates fluid effusions or collections adjacent to the kidney, most often in
the perirenal space as a multiloculated, thick-walled, hypoechoic mass (fig. 1) [2].
Color and power Doppler Ultrasound may show a periodic jet flow at the leak
demonstrating its origin [2].
Contrast-enhanced Multidetector Computed-Tomography (MDCT) is the study of
choice in the diagnosis of urinary tears (fig. 5) [1].
•
•
•
Specially with delayed images, MDCT can demonstrate the leak because
iodinated urine increases the attenuation of the urinoma over time (fig. 3,
6-8) [1].
Moreover, coronal and sagittal three-dimensional (3D) reformatted images
defines the site of the tear and the extent of the collection (fig. 9).
MDCT is also helpful during follow-up and after treatment, showing possible
complications in the surrounding tissues (fig. 10) [5,6]. Complications
result from irritation by urine, as a fluid collection with air inside because of
superinfection favored by urinary stasis (fig. 11, 12).
Page 6 of 45
Intravenous Pyelograph has a low sensitivity in the diagnosis of urine leaks and can
demonstrate normal findings in over 30% of cases of renal injury (fig. 2, 4) [7].
- Treatment:
•
Small urinomas can reabsorb spontaneously [6]
•
If urinoma is larger or if the patient developed septic fever, drainage is
mandatory [1]:
- the drainage catheter can be positioned under US or CT guidance in the most
dependent portion of a urinoma;
- if urinoma do not reduce its volume, a percutaneous nephrostomy catheter may be
placed in addiction to the other to decompress the collecting system in order to facilitate
urinary drainage;
- in cases of persistent leakage from the collecting system, placement of a nephrostomy
catheter, usually with a ureteral stent or nephroureterostomy catheter, is warranted in
order to promote primary healing of the collecting system.
Treatment
# URETERAL LEAKS
- Causes:
•
iatrogenic injury during percutaneous or surgical procedures
•
urinary obstruction (ureteral stone, abdominal or pelvic masses,
retroperitoneal fibrosis)
•
ureteral anastomotic dehiscence (following renal transplantation or other
ureteral procedures)
•
blunt or penetrating abdominal trauma (ureteral laceration)
Causes of ureteral leaks
Page 7 of 45
- Imaging:
Ureteral injuries can be demonstrated mainly with:
- Retrograde Pyelography
- Antegrade Pyelography
- Contrast-enhanced MDCT
MDCT with unenhanced, venous and delayed phases, is the least invasive and most
readily available of these three exams [1].
•
•
•
The absence of opacification in the distal portion of the ureter is a sentinel
CT finding of ureteral tear [2].
The fluid might accumulate close to lacerated ureter and/or drain into
adjacent portions if confined into retroperitoneal compartment (fig. 13, 14),
(fig. 15, 16) (fig. 17, 18) [8,9]. Urinary ascites is more frequent in cases of
ureteral leaks, depending on anatomic position of ureter (fig. 19).
Urinary stasis can favored bacterial superinfection; in these cases, CT scans
shows a fluid collection with air inside (fig. 20).
In cases of ureteral leaks, US can reveal an hypoechoic fluid mass near the ureter, even
if fluid leaking from an ureter can accumulate in various location.
It can also demonstrate the dilatation of upper urinary collecting system because of a
downstream obstruction.
Color and power Doppler ultrasound, by demonstrating ureteral origin of the jet flow,
may contribute to the diagnosis [2].
- Treatment:
•
percutaneous urinoma drainage along with diversionary percutaneous
nephrostomy with or without ureteral stent placement
•
nephroureteral catheters positioning across the site of ureteral injury
Treatment
# URINARY BLADDER LEAKS
Page 8 of 45
- Causes
•
blunt or penetrating renal trauma (pelvic trauma)
•
iatrogenic injury during percutaneous or surgical procedures
Causes of urinary bladder leaks
- Imaging:
Historically, Retrograde Cistography is the diagnostic test of choice in evaluating urinary
bladder injury, but it can underestimate the extent of an intraperitoneal leak [10].
Therefore, CT-Uroghraphy is now preferred as studies of choice, specially to detect
causes and extent of bladder injury (fig. 21) (fig. 22-26, 27, 28).
At many institution is now performed CT-Cistography: after the retrograde instillation of
diluted contrast material into the urinary bladder, abdominopelvic imaging is obtained [1].
There are two types of bladder injury [10]:
EXTRAPERITONEAL
(65%)
Causes
•
INTRAPERITONEAL
(35%)
pelvic fractures
•
CT- findings
- flame-shaped
extravasation into
perivescical soft tissue
blunt trauma
leading a
rapid rise in
intraperitoneal
pressure
- leakage
material
of
contrast
and urine around bowel
loops and into paracolic
gutters
Types of bladder injury
Page 9 of 45
- Treatment [10]:
EXTRAPERITONEAL
INTRAPERITONEAL
- Bladder drainage catheter alone or
sovrapubic catheter if there is gross - Open surgical exploration
hematuria
# URETHRAL LEAKS AND URINOMAS
- Causes:
•
blunt or penetrating trauma
•
chronic infection
Causes of urethral leaks
Urethral injuries are classified as:
•
•
•
contusions
partial disruptions
complete disruptions
They may involve the posterior or the anterior urethral segment:
- posterior urethral injuries occur almost exclusively with pelvic fractures;
- anterior urethral injuries are often consequences of a perineal straddle injury from a fall,
perineal blow, or motor vehicle collision.
- Imaging:
Retrograde Urethrography is the examination of choice in case of urethral injury
specially to evaluate the caliber of the uretra and to diagnose the leak site (fig. 29) [1].
Page 10 of 45
Extravasation of contrast, injected until uretra meatus, demonstrates the location of the
tear (fig. 30-32).
Computed tomography (CT) is useful as a frontline imaging modality for blunt
abdominopelvic trauma, specially in evaluating pelvic fractures and the severity of trauma
injuries.
CT often demonstrates indirect signs of urethral injuries:
•
•
•
•
•
•
elevation of the prostatic apex
extravasation of urinary tract contrast material above or below the urogenital
diaphragm (UGD)
distortion or obscuration of the UGD fat plane
hematoma of the ischiocavernosus muscle
distortion or obscuration of the prostatic contour and of the bulbocavernosus
muscle
hematoma of the obturator internus muscle
- Treatment:
•
conservative management with transurethral bladder catheter placement
•
suprapubic cystostomy positioning to divert urine flow, possible in
combination with abdominal, perineal, or scrotal catheter drainage of a
urine leak
•
surgical reconstruction of the urethra in case of severe urethral rupture
to prevent long-term urinary complications such as urethral stricture
formation, impotence, urethral fistulization, and incontinence
Treatment
Images for this section:
Page 11 of 45
Fig. 1: Renal leaks: ultrasound appearances and features. Arrows indicate fluid collection
in the perirenal space in a 34-years-old patient with right uretheral stone.
Page 12 of 45
Fig. 2: Renal leak: urographic appearances and features in the 34-years-old patient with
right uretheral stone. Pyelography shows a leak that originates from a diverticula in the
major inferior calyx.
Page 13 of 45
Fig. 3: Renal leak: CT appearances and features in the 34-years-old patient who had
received an abdominal trauma. Delayed phase confirms the leak and shows the fluid
collection near right kidney.
Page 14 of 45
Fig. 4: Renal leak: urographic appearances and features in the 34-years-old patient
with right uretheral stone. After surgery, pyelography shows the leakeage repair and the
disappearence of the fluid perirenal collection.
Page 15 of 45
Fig. 5: Renal leak: main CT findings.
Page 16 of 45
Fig. 6: Renal leak: a 47-years-old drug-addict patient who developed necrosis of superior
calices of the left kidney because of drugs ischemia. Baseline scans show a confined
collection near the left kidney associated with renal fascia thickening.
Page 17 of 45
Fig. 7: Renal leak: venous phase scans show the confined fluid collection near the left
kidney with renal fascia thickening progressive enhancement.
Page 18 of 45
Fig. 8: Renal leak: delayed phase scans show the progressive increase of the attenuation
values of urinoma because of iodinated urine leak.
Page 19 of 45
Fig. 9: Renal leak: MPR reconstructions show the site of the injury in a minor calyx of
the middle portion of the kidney.
Page 20 of 45
Fig. 10: Renal leak: follow-up and complications.
Page 21 of 45
Fig. 11: Renal leak follow-up and complications: CT scans in the same patient as before
obtained two months after percutaneous urinoma drainage, show the reduction of the
fluid collection but also the development of an abscess with air inside because of bacterial
superinfection.
Page 22 of 45
Fig. 12: Renal leak: follow-up and complications (venous phase).
Page 23 of 45
Fig. 13: Ureteral leak: a 35-years-old female who developed urinoma after a gynecologic
surgery. Delayed phase shows a fluid iodinated collection in the left sigmoid mesentery
not visible in the unhenenced scans on the left.
Page 24 of 45
Fig. 14: Ureteral leak: MPR reconstruction shows the site of ureteral injury (arrow) and
a fluid iodinated collection.
Page 25 of 45
Fig. 15: Ureteral leak: a 65-years old woman who developed ureteral tears after
retroperitoneal lyposarcoma exportation. Delayed CT scans demonstrate a iodinated
collection extended from distal ureter tear to left iliac crest.
Page 26 of 45
Fig. 16: Ureteral leak: MPR reconstructions show the spread of iodinated fluid collection
from the lacerated distal ureter to left iliac crest.
Page 27 of 45
Fig. 17: Ureteral leak: urinoma developed in Ureteropelvic Junction Obstruction in a 71years-old female. Delayed phase shows a fluid iodinated collection near the ureteropelvic
junction and its drainage into the perirenal space.
Page 28 of 45
Fig. 18: Ureteral leak: sagittal MPR reconstructions demonstrate the drainage of fluid
iodinated collection from ureteropelvic junction into the lower portion of the perirenal
space.
Page 29 of 45
Fig. 19: Ureteral leak: free fluid collection (urinary ascites with HU > 10) in a 38-yearsold female patient who underwent to cistectomy because of bladder penetrating trauma.
Page 30 of 45
Fig. 20: Ureteral leak: encapsuled fluid collection in the right side with air inside
(superinfection) in a patient who underwent urologic surgery.
Page 31 of 45
Fig. 21: Urinary bladder leak: imaging.
Page 32 of 45
Fig. 22: Urinary bladder leak: a 61-years-old man who presented with abdominal pain four
days after undergoing ureteral resection (Politano-Leadbetter) for urothelioma. Baselines
scans show a fluid collection near urinary bladder.
Page 33 of 45
Fig. 23: Urinary bladder leak: in the same patient venous phase highlights the fluid
collection.
Page 34 of 45
Fig. 24: Urinary bladder leak: delayed phase demonstrates the presence of a leak in the
postero-lateral wall of urinary bladder, near the ureteral replacement site.
Page 35 of 45
Fig. 25: Urinary bladder leak: MPR reconstruction showing the leak.
Page 36 of 45
Fig. 26: Urinary bladder leak: MPR reconstruction showing the leak.
Page 37 of 45
Fig. 27: Urinary bladder leak: surgical repair of urinary bladder leaks.
Page 38 of 45
Fig. 28: Urinary bladder leak: retrograde cistography two days later surgical repair, shows
a leakage near the drainage (arrow).
Page 39 of 45
Fig. 29: Urethtral leak: imaging.
Page 40 of 45
Fig. 30: Urethtral leak: retrograde cistography in a 72-years-old woman two months later
urinary incontinence surgery. Urethrograms show bilateral urethral leaks (arrows) only
in the voiding phase.
Page 41 of 45
Fig. 31: Urethtral leak: retrograde cistography in a 59-years-old man who received a
trauma. Urethrograms show a periurethral collection of contrast material (arrow).
Page 42 of 45
Fig. 32: Urethtral leak: retrograde cistography in a 75-years-old man three months later
radical prostatectomy. Urethrograms show iodinated urine leak in the vesico-urethral
anastomosis site.
Page 43 of 45
Conclusion
In urine leaks and urinoma, imaging plays a key role:
1.
2.
3.
4.
to allow accurate assessment of cause and extent of the leakeges
to help preventing complications such abscess, electrolyte imbalances,
hydronephrosis and paralytic ileus
to preserve renal function
to determine the best therapeutic approach for a successful treatment
Therefore, diagnostic imaging plays a crucial role in promptly identifying urinary
leaks and their cause/extent, and during follow-up.
Personal Information
Barbara Ginanni, MD
(barbaraginanni@hotmail.com)
Department of Oncology, Transplants and New Technologies in Medicine
Division of Diagnostic and Interventional Radiology
University of Pisa
ITALY
References
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