AJR 2002; 178:1191-1193
© American Roentgen Ray Society
Removal of Renal Fungus Balls Using a Mechanical Thrombectomy Device
Frank A. Morello, Jr.1,
Alberto V. Mansilla and
Michael J. Wallace
1 All authors: Section of Vascular and Interventional Radiology, The University
of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., P. O. Box 325,
Houston, TX 77030.
Received September 10, 2001;
accepted after revision November 9, 2001.
Address correspondence to F. A. Morello, Jr.
Introduction
Fungal bezoars in the upper urinary tract are a rare cause of obstructive
uropathy. Renal involvement is commonly caused by disseminated candidiasis,
but a primary infection can be caused by an ascending process or via urinary
drainage catheters. Mycetomas are common in premature neonates. However,
mycetomas can also occur in patients whose immune systems have been suppressed
by chemotherapy or corticosteroids or who have used broad-spectrum antibiotics
for prolonged periods, have a continual need for central venous catheters or
urinary tract drainage catheters, have diabetes, or have undergone surgical
procedures [1]. The therapeutic
goals are to relieve urinary obstruction and to clear the fungal mass. Usual
treatments involve percutaneous renal access for either surgical removal or
renal pelvis irrigation with antifungal agents. To our knowledge, only a
handful of reports describe alternative percutaneous mechanical techniques to
debulk renal mycetoma. We report a case of percutaneous treatment of bilateral
renal pelvis mycotic bezoars using a mechanical thrombectomy device (AngioJet
Rheolytic Thrombectomy System; Possis Medical, Minneapolis, MN) followed by
antifungal renal pelvis irrigation.
Subjects and Methods
A 43-year-old man undergoing chemotherapy for retroperitoneal follicular
small cell lymphoma had bilateral nephroureteral catheters that frequently
occluded, causing obstructive nephropathy and chronic progressive renal
insufficiency (baseline creatinine, 3.0-3.5 mg/dL). As a part of a renal
disease regimen, he received a low-dose ciprofloxacin (Cipro; Bayer
Pharmaceuticals, West Haven, CT) for continuing suppression of bacterial
infection to reduce risks of further deterioration.
After experiencing a progressive decrease in urine output, the patient
underwent antegrade nephrostography and nephroureteral catheter replacements
that revealed bilateral filling defects casting the upper urinary tracts
(Fig. 1A). Urinalysis confirmed
the presence of Candida albicans, and the patient was started on oral
antifungal medication. Five days later, he presented to the emergency
department with shortness of breath and metabolic acidosis (pH, 7.21). Chronic
bilateral pleural effusions were the only signs of volume overload. At
admission to the hospital, the patient's serum creatinine and potassium levels
were 9.7 mg/dL and 3.2 mmol/L, respectively. After the patient was given
hemodialysis, nephrostograms showed that there had been no improvement in the
bilateral renal pelvis filling defects.
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Fig. 1A. —43-year-old man with retroperitoneal lymphoma who underwent
imaging because of progressive decrease in urine output. Urinary analysis
showed Candida albicans infection. Fluoroscopic nephrostogram reveals
fungus casting right upper urinary collecting system (similar appearance on
left side, not shown).
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Once we made the decision to perform percutaneous fungal extraction, we
replaced the nephroureteral catheters with 10-French vascular sheaths. The
thrombectomy device was directed through the sheaths and over a 0.035-inch
angled guidewire (Glidewire; Boston Scientific, Watertown, MA) into all major
calices, each renal pelvis, and both proximal ureters
(Fig. 1B). This procedure
lasted approximately 15 min on each side; we used intermittent fluoroscopy to
minimize radiation exposure. Postinterventional nephrostograms showed a
complete clearance of fungus in the right urinary tract
(Fig. 1C) and a small residual
filling defect in the left upper urinary tract
(Fig. 1D). The patient
experienced no complications during or after the procedure and received 12
days of irrigation with 15 mg/hr of amphotericin B (for injection, Amphocin;
Pharmacia, Peapack, NJ) via the replaced nephroureteral catheters.
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Fig. 1B. —43-year-old man with retroperitoneal lymphoma who underwent
imaging because of progressive decrease in urine output. Urinary analysis
showed Candida albicans infection. Fluoroscopic nephrostogram shows
thrombectomy device in right renal collecting system during fragmentation and
removal of fungus ball.
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Fig. 1C. —43-year-old man with retroperitoneal lymphoma who underwent
imaging because of progressive decrease in urine output. Urinary analysis
showed Candida albicans infection. Fluoroscopic nephrostograms
obtained immediately after intervention show complete clearing of collecting
system on right side (C) and residual filling defect in collecting
system on left side (D).
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Fig. 1D. —43-year-old man with retroperitoneal lymphoma who underwent
imaging because of progressive decrease in urine output. Urinary analysis
showed Candida albicans infection. Fluoroscopic nephrostograms
obtained immediately after intervention show complete clearing of collecting
system on right side (C) and residual filling defect in collecting
system on left side (D).
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Hemodialysis was discontinued 10 days after percutaneous intervention, and
the patient's creatinine returned to the baseline level (3.2 mg/dL). The
residual fungus in the left upper urinary tract was then completely cleared in
another session with the thrombectomy device. The right collecting system
remained free of mycetoma. Six hours after the second intervention, the
patient developed fever and chills. He was given IV vancomycin hydrochloride
(Abbott Laboratories, Abbott Park, IL) and ciprofloxacin. The results of blood
cultures remained negative. The patient's symptoms resolved, and use of the
antibiotics was discontinued 3 days later. Results of urine cultures obtained
15 days after the final intervention were negative. The patient was discharged
from the hospital with a serum creatinine level of 4.5mg/dL.
Results
One month later, the patient was still off hemodialysis with a stable serum
creatinine level. Antegrade nephrostograms obtained 3 months after the
procedures revealed no evidence of residual mycetoma in either renal
collecting system. Despite these results, the patient's renal insufficiency
progressed, and hemodialysis was reinstituted.
Discussion
Initially, we suspected mycetoma on the basis of nephrostograms that showed
extensive defects in both of the patient's upper collecting systems. The rapid
development and bilateral involvement made an infectious process more likely
than other common possibilities in the differential diagnosis, such as blood
clots, a neoplasm, or radiolucent calculi. Several compounding risk factors
likely contributed to mycetoma formation including chemotherapy-induced
immunosuppression, continual use of nephroureteral catheters, and antibiotic
suppression therapy for preservation of renal function.
The reported therapeutic options for renal fungus balls are limited and
range from conservative medical management with antifungal irrigation to
surgical evacuation. In a study of 14 neonates, Benjamin et al.
[2] used systemic antifungal
therapy for non-obstructive mycetoma. An average of 80 days of therapy (range,
10 days-4 months) was required for complete resolution. In patients with
obstructive uropathy, invasive techniques may be required. Percutaneous
nephrostomy catheter insertion and urinary tract irrigation with amphotericin
B have been reported as treatments for mycetoma in several case reports and
small series [3,
4]. More aggressive extraction
techniques have been described in a small number of case reports. Bell et al.
[4] successfully used antegrade
access for guidewire fragmentation and subsequent renal pelvis irrigation in
three patients. Doemeny et al.
[5] dilated a nephrostomy tract
and, under fluoroscopic guidance, extracted a mycetoma using a stone basket
through a 26-French sheath. Percutaneous endoscopic removal has also been
described as an effective technique in debulking renal fungus balls
[6,7,8].
In the approach described in this report, we use a low-profile (6-French)
device recently approved by the Food and Drug Administration for
catheter-based mechanical removal of coronary and peripheral arterial
thrombus. The thrombectomy catheter tip contains jets that produce an
intensified Venturi effect, capturing thrombus or other material into an
efferent catheter lumen. This technology has been effective for thrombectomy
in dialysis grafts as well as in native arteries and veins. The isovolumetric
saline injection and removal procedure is ideal to use in closed spaces, such
as thrombosed grafts or, as in our patient, an obstructed collecting system in
which increased pressure could cause pyelovenous backflow and subsequent
fungemia. Even though our patient experienced a febrile episode, we believe
that it was not triggered by overdistention of the collecting system but
rather by a guidewire tear in a calix, causing a transient fungemia that did
not progress. On contrast-enhanced images, we observed some faint evidence of
such an occurrence, but it did not persist. The completely closed drainage
system allowed us to perform a procedure in an infected space without
contamination of the machine or the operator. We then disposed of the closed
drainage bag with fungal content according to biohazard safety guidelines.
The consistency of renal fungus has been described as "sludge"
and has been effectively removed by irrigation and suction through a 26-French
nephroscope [6]. This
consistency, similar to that of recently clotted blood, gave us the incentive
to attempt fragmentation and aspiration in a manner similar to that performed
for vascular catheter-based thrombectomy. Most percutaneous techniques, such
as the one described by Doemeny et al.
[5], require nephrostomy tract
dilation. The advantage of our small-profile catheter approach is that it
eliminates the need to dilate the nephrostomy tract and decreases the
potential for transient pericatheter leaking during the time required to
reestablish a 10-French catheter tract. This procedure can also be performed
with the patient under conscious sedation rather than under the general
anesthesia occasionally required for endoscopic maneuvers.
To our knowledge, no large series have been performed to determine the best
therapeutic intervention for obstructive mycetoma. A combination approach
seems to be the usual starting point. The use of a thrombectomy device may
prove to be an effective and minimally invasive adjunct intervention to either
systemic or local antifungal therapy.
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Introduction
Subjects and Methods
