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284 J.J. Trambert
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nosis. Renal cell carcinoma, Wilms’ tumor, and even angiomyolipoma and benign renal adenomas can present
similar angiographic appearances. In addition, renal cell
carcinoma, although usually hypervascular, occasionally
is avascular, making angiographic distinction from a simple cyst difficult (Fig. 23-15). Inflammatory infiltrative
disease such as xanthogranulomatous pyelonephritis
sometimes results in a neovascularity similar to a moderately vascular renal cell carcinoma. Frequently, the correct diagnosis is made by correlating clinical history, noninvasive imaging studies, and angiographic findings;
however, the definitive diagnosis is not available until
histologic evaluation of the resected surgical specimen is
complete.
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M.E. RacksonObstructiveUropathy and Renal Calculus Disease
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24
■■■
Obstructive Uropathy and
Renal Calculus Disease
MARLENE E. RACKSON
Ureteral obstruction leads to dilation of the proximal ureter and hydronephrosis. This chapter deals with percutaneous nephrostomy (PCN) and ureteral stenting procedures, which are used to relieve obstruction and help in
the management of renal calculus disease.
■ Clinical Presentation
Many patients presenting with obstructive uropathy have
malignancies; the etiology and the obstruction can be
bilateral or unilateral. When both kidneys are obstructed,
the patient will present in renal failure with elevated
blood urea nitrogen (BUN) and creatinine levels. This
clinical picture often is seen in patients who have prostate
cancer, bladder cancer, or gynecologic malignancies. Because malignancies grow slowly, they cause the kidney to
dilate slowly. Thus, malignant obstruction is usually painless. Unilateral obstruction caused by malignancy may be
difficult to diagnose clinically if the other kidney is functioning normally, because the obstruction is painless and
the BUN and creatinine levels may be normal. Unsuspected unilateral obstruction often is detected during the
course of an imaging study such as ultrasound or computed tomography (CT) of the abdomen. The decision
to treat an asymptomatic unilateral obstruction caused by
malignancy is a clinical one that may be influenced by
many factors, such as the need to optimize renal function
before administration of chemotherapy with known nephrotoxicity (Fig. 24-1).
Patients undergoing PCN for benign causes of obstruction usually have calculi or strictures. Only a small fraction of patients presenting with renal stones require per-
4,5
1–3
cutaneous decompression. In the acute setting, a patient
with pyonephrosis may have severe flank pain, fever, elevated white blood cell (WBC) count, and other signs of
infection along with a stone and hydronephrosis identified on an imaging study.
performed to provide preoperative access to the renal
collecting system in patients about to undergo percutaneous nephrolithotomy (PNL).
Ureteral strictures also may be treated by percutaneous
methods. Causes of strictures include radiation, retroperitoneal fibrosis, prior instrumentation, and fistulae. These
patients may present with one or many signs and symptoms: fever, flank pain, renal failure, hydronephrosis, or
urinoma formation on imaging studies.
Patients with renal allografts (transplants) may present
with urine leaks, ischemic ureter, and obstruction and
may be treated with PCN. Percutaneous procedures also
are used to perform Whitaker tests (see Chapter 9), which
measure the pressure gradient across a ureteral stenosis,
to infuse antibiotics for fungal infections, to infuse agents
for stone dissolution, and to provide access for removal
of encrusted stents.
■ Differential Diagnosis
The need fora PCN is generally straightforward. The presence or absence of hydronephrosis can be determined
quickly, safely, and with certainty by ultrasound or CT scanning. The proper clinical setting will confirm the need for
the procedure. Hydronephrosis can be due to reflux,however, and does not always mean obstruction or translate
into a need for a PCN. Furthermore, it is important to
8–10
6
In the elective setting, PCN is
7
287
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FIGURE 24-1. Percutaneous nephrostomy (PCN) placed to
relieve ureteral obstruction resulting from cervical carcinoma.
Note that the tube enters the collecting system below the costal
margin through a posterior mid–lower pole calyx, which provides safe avascular access and a good “pushing angle” for
future attempts at ureteral stent placement. Irregularity of upper ureter is due to ureteritis cystica.
inine levels are rising but there is minimal hydronephrosis, also can occur. Although the renal failure is most
likely due to medical renal disease, there is also the possibility of obstruction without dilation, which occurs when
the kidney shuts down before it dilates. This type of obstruction has been reported in patients with prostatic carcinoma.
11
Although this situation is unusual, it should be
kept in mind because percutaneous decompression will
improve renal function.
PCN should be performed as an emergency proce-
12
dure
in the following situations:
1. In the setting of high fever and elevated WBC count
or frank sepsis, when the patient is suspected of
having pus in the kidney: This is usually seen in a
patient with hydronephrosis and an identifiable obstructing calculus causing urosepsis.
2. Iatrogenic trauma to the ureter that is recognized
when it happens: If the urologist calls from the
operating room and says that the ureter has been
dissected, the patient should have a PCN to divert
the urine and to avoid urinoma formation. Stent
placement to preserve the integrity of the ureter
and avoid stricture formation should be attempted.
3. Severe unmanageable flank pain resulting from an
obstructing calculus or steinstrasse from a preceding extracorporeal shock-wave lithotripsy (ESWL)
treatment: Decompression via a PCN (antegrade
approach) or a ureteral stent placed by the urologist
(retrograde approach) will provide pain relief.
4. Acute renal failure resulting from bilateral obstruction or obstruction in a solitary kidney: This procedure should be done urgently to preserve renal
parenchyma and to induce a diuresis to correct
fluid and electrolyte imbalances.
determine whena PCNis elective and whenthe procedure
needs to be performed as an emergency.
Some patients have chronic hydronephrosis (determined from serial imaging studies) with a new elevation
of the BUN and creatinine levels. In the patient with a
solitary kidney, PCN is certainly indicated to preserve the
remaining renal parenchyma. The same is true when one
kidney demonstrates cortical atrophy and the other demonstrates relatively normal cortex: The more normal kidney should be decompressed. When bilateral cortical atrophy and hydronephrosis are present, progressive renal
failure may not be stabilized or improved by decompression. Sometimes the only way to prove or disprove the
value of decompression in preserving renal function is to
perform the PCN and then remove the tube if the kidney
does not produce urine or if the function on a nuclear
medicine scan does not improve.
The opposite situation, in which the BUN and creat-
■ Treatment Alternatives
Whenever possible, the retrograde approach (i.e., opposite the direction of flow of urine) to ureteral stent placement is preferable to the antegrade approach. The retrograde approach, usually performed by the urologist, has
the advantage of avoiding creation of an 8 or 10 Fr hole
extending from the flank to the kidney, which can be
complicated by bleeding and may produce pain. Retrograde ureteral stent placement is also a one-step procedure, whereas antegrade stent placement may require at
least two visits to the radiology department: first for the
initial nephrostomy and then for placement of the stent.
Until the antegrade stent has been placed and the urine
is free of blood, the patient must wear an external nephrostomy bag (so that the stent will not occlude from
blood clots). Patients who have small ureteral calculi and
require stents with normal bladders and visible ureteral
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289
A B
FIGURE 24-2. A: “Upside down” percutaneous nephrostomy (PCN) to relieve hydronephrosis in a patient with an ileal conduit.
After standard PCN access is achieved, a guidewire is maneuvered down the ureter into the conduit. The guidewire is retrieved
from the conduit, and an “upside down” PCN is inserted. The external portion of the PCN lies in the ostomy bag rather than
exiting the flank. Completely internalized stents occlude rapidly because of mucus production in the conduit. B: Tubes can be
changed easily over a guidewire from the ostomy site.
orifices and patients undergoing precautionary ureteral
stenting prior to bowel or pelvic surgery are examples of
two situations in which retrograde ureteral stenting is
preferable to the antegrade approach and is usually successful. In patients with malignant obstructions at the
level of the ureterovesicle junction, the ureteral orifice
often cannot be identified and attempts at retrograde
vention usually are treated by ESWL rather than by PNL;
however, when ESWL is not applicable or has failed, percutaneous approaches areused. Situations in which ESWL
is not applicable are stones larger than 3 cm, cysteine
stones, lucent or infected stones, large staghorn calculi,
and stones trapped in an infected calyx. Open surgery is
rarely necessary for the treatment of stone disease.
stent placement will usually fail. In fact, many patients
undergo percutaneous procedures after failure of the
retrograde approach.
■ Imaging Workup
Although retrograde approaches usually areperformed
by the urologist, they also can be performed by the interventional radiologist. This approach is easier in female
patients because the urethra is shorter than in male patients. On occasion, the urologist will be able to advance a
small catheter fromthe urethra into the ureter butwill not
be able to place a true stent. If the patient is transferred to
the radiology suite with the catheter still in place, the
interventionalist often will succeed in retrograde placement of the stent, thereby avoiding nephrostomy. Retrograde approaches also can be useful in patients with ileal
conduits and other diversionary pouches (Fig. 24-2).
13
Actually, most cases of stone disease that require inter-
When a patient is referred for a PCN to relieve obstruction, an imaging study is needed to prove hydronephrosis.
This may be done quickly and easily by using ultrasound,
which also will demonstrate cortical thickness and the
level of obstruction, as well as the presence of stones and
potential technical difficulties such as large cysts, urinomas, and duplicated collecting systems. The ultrasound
machine also can be wheeled into the interventional suite
and can be very helpful in localizing the kidney. The more
costly CT scan gives the same information as the ultrasound, but it also shows the level of the kidney, which, if it
is located unexpectedly high or low, could make fluoro-
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scopic localization difficult. Sometimes an excretory urogram is performed just before the PCN (usually in stone
cases); if there is contrast in the collecting system of the
obstructed kidney, access to the collecting system is facilitated.
PCNs often are performed to provide access to the
renal collecting system prior to PNL.
14,15
Excretory urograms and retrograde pyelograms are best for locating
the number and size of stones in the intrarenal collecting
system before access for removal. When outpatients arrive for procedures, often only a clinical history has been
provided but no studies are available. In this situation,
good prone scout films with 30-degree obliques before
and after contrast is injected should be obtained, either
intravenously or through an antegrade pyelogram (direct
skinny-needle puncture into the renal pelvis).
■ Interventions: Percutaneous
Nephrostomy and Ureteral Stenting
The approach to the PCN could be titled, “Why are we
doing this case?” The goal of the procedure will determine how general or specific the puncture into the collecting system needs to be. The main goals of PCN are to
relieve obstruction (the simplest approach), to stent the
ureter (the more specific approach), and to provide access for stone removal (the approach that requires the
most planning and is the most specific).
PCN to relieve obstruction
When the goal of the PCN is to relieve obstruction by
providing external drainage without planning any further
interventions, a nonspecific approach will suffice. Essentially any access from the flank to the intrarenal collecting
system will be sufficient as long as the tube traverses the
renal cortex (to anchor the tube) and enters through a
calyx (an avascular area that does not have large crossing
vessels) and direct pelvic punctures are avoided (see Fig.
24-1). The initial puncture can be made into the renal
pelvis from a direct posterior translumbar approach in
order to opacify the collecting system; a skinny (21- or
22-gauge) needle should be used. The final entry site into
the kidney should be roughly along the posterior axillary
line, below the 12th rib. An entry site that is too medial
will be too posterior and will be uncomfortable for the
patient. An entry site that is too lateral runs the risk of
puncturing the colon. A subcostal approach will avoid the
risk of pneumothorax and the potential for periosteal
pain from a tube placed between the ribs as well as avoiding the liver and spleen.
as the Neff set (Cook, Inc., Bloomington, IN) or the Accustick set (Medi-tech, Boston, MA) have been more fully
described previously. Establishment of percutaneous ac-
16,17
Percutaneous access kits such
cess is followed by tract dilatation and placement of the
PCN tube.
When frank pus is aspirated from the intrarenal collecting system, only external drainage should be performed.
Contrast injections will pressurize the collecting system
and increase the risk of sepsis resulting from pyelovenous
backflow. These injections should be limited to a few
milliliters, just enough to confirm needle placement in
the collecting system. Catheter and guidewire manipulations in a grossly infected collecting system also increase
the risk of sepsis resulting from pyelovenous backflow
and must be minimized. The aspirated material should
be sent for Gram’s stain and culture and sensitivity.
The initial drainage procedure in a renal transplant
patient should be kept simple. Because the allograft is
placed anterior to the iliac wing in the pelvis, the procedure is done with the patient in a supine position, not
prone (Fig. 24-3). The hydronephrotic renal pelvis is
anterior to the calyces and is sometimes palpable under
the anterior abdominal wall. Therefore, the initial drainage procedure is often through a puncture directly into
the renal pelvis.
8
Ultrasound guidance not only localizes
the transplant kidney, it also eliminates the possibility of
transgressing an interposed bowel loop.
Ureteral stenting and specific techniques
of stent insertion
Internal ureteral drainage through a stent is preferable to
external drainage with a leg bag for the urine. Whenever
possible, access for the PCN should be planned in anticipation of ureteral stent placement, which entails creating
a favorable angle for pushing a catheter across a ureteral
lesion. In a normally located kidney, middle-pole calyces
are preferable to lower-pole calyces, which require pushing a catheter upward to the renal pelvis and then downward into the ureter. If the kidney is high above the ribs
and the patient cannot inspire deeply enough to depress
the kidney, only lower-pole calyces will be accessible for
puncture. Conversely, if the kidney is ptotic, superior pole
calyces may be low enough to puncture and will provide a
straight downward line of pushing force into the ureter.
Ureteral stenting is indicated in the presence of benign and malignant strictures, fistulae, some stones,
trauma, and iatrogenic complications (Fig. 24-4). The
length of time a ureteral stent remains in place depends
on why the stent was placed. Stents for strictures and
fistulae can be in place anywhere from 3 weeks to 3
months. Stents for malignant strictures are usually permanent. All patients who require long-term stenting
should have the stents exchanged every 3 to 6 months to
prevent encrustation and occlusion of the stent by urinary sediment. The stent can be inserted at the time of
the original PCN or after the kidney has been decompressed at a separate session.
18–20
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A
C
There are two basic types of stent: the completely internalized ureteral stent and the nephroureteral stent (NU)
(Fig. 24-5).
The internalized stent
The internalized ureteral stent lies completely within the
body and extends the length of the ureter from the renal
pelvis to the bladder.This stentis commonlycalled adouble
pigtail or doubleJ stent, which refers to the shape of the tips
of the stent. The proximal pigtail or J-shaped tip anchors
the stent in the renal pelvis and prevents it from slipping
down into the bladder. The distal pigtail prevents the tip
B
FIGURE 24-3. Distal ureteral stricture in a transplant kidney.
A: Antegrade nephrostogram demonstrates marked hy-
dronephrosis with a stricture of the distal ureter. Note the
position of allograft over the iliac bone and the presence of a
J-tip “safety wire” in the renal pelvis. B: The stricture was
dilated with a 12-mm-high pressure balloon. C: An internal–external stent was placed across the stricture for 6 weeks following the procedure.
from wedging into the bladder wall and causing discomfort or exiting the urethra. For a patient who requires
long-term stenting, a completely internalized stent is preferable because the patient does not have to wear a leg bag
with its attendant discomfort and lifestyle inconveniences.
Interventional radiologists usually place 8 or 10 Fr stents
from the antegrade approach, whereas urologists usually
place 5 or 6 Fr stents from the retrograde approach.
The nephroureteral stent
The NU is a one-piece combination of a nephrostomy
tube and an internal ureteral stent that extends from the
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A B
FIGURE 24-4. Bilateral percutaneous nephrostomy (PCN) tubes placed for urinary diversion after attempt at suprapubic
cystostomy resulted in an intraperitoneal bladder perforation. A: Cystogram demonstrates contrast extravasation superior to the
bladder. B: Bilateral PCN tubes alongside ureteral occlusion balloons placed to prevent any urine from flowing into the bladder.
(
arrows
)
skin into the renal pelvis and descends through the ureter to terminate in the bladder. The NU can be left to
external drainage with a leg bag, or it can be capped off
to promote internal drainage.
Internalized ureteral stents usually are replaced by us-
ing cystoscopy.
21
If the exchange is anticipated to be
difficult, an NU tube that is capped off to external drainage is a good solution, because the tube can be simply
replaced over a guidewire.
The NU often is placed during the initial PCN procedure when an internal stent is eventually planned.
Frequently, the ureteral obstruction can be transversed
during the initial PCN, but the procedure is bloody.
the trial of internal drainage fails, the internal portion of
the NU may be occluded, or there may also be a bladder
outlet obstruction. If an internal stent is placed in the
presence of a bladder outlet obstruction, hydronephrosis
would persist because the urine in the bladder would
reflux up the stent and the patient would still require a
Foley catheter to drain the bladder.
22
An NU tube left to
external drainage will decompress the kidney and the
urinary bladder, which drains the other kidney, without
the need for the Foley. Even if the patient has only one
kidney and a bladder outlet obstruction, a long NU is less
likely than a short PCN tube to fall out inadvertently
because it is more firmly anchored.
Placement of a completely internalized ureteral stent in
a bloody system will not allow adequate flushing and the
stent may clot; therefore, the NU is placed until the urine
is clear. Once the urine has cleared, the NU is capped off
to external drainage overnight to determine whether the
patient can void normally without developing fever, flank
pain, or urine leaking around the tube at the skin. If
these events occur, the tube should be reopened to external drainage. An NU tube always should be left to external drainage whenever the urine is bloody, the patient is
febrile, or the urine is infected. If the patient tolerates
capping the tube, the NU can be replaced easily by an
internal stent using a stiff guidewire for the exchange. If
Specific techniques of stent insertion
The preexisting PCN tube or percutaneous access catheter is removed from the renal pelvis over a stiff guidewire,
such as an Amplatz Superstiff (Meditech, Boston, MA)
wire, and is replaced fora short directional catheter witha
distal curve such as a cobra or hockey stick shape, and the
system is opacified with dilute contrast injections. The
ureteropelvic junction is engaged with the catheter tip and
a floppy-tipped wire (Bentson) or hydrophilic guidewire
(Glidewire Meditech, Boston, MA), and the catheter–wire
combination is advanced down the ureter to the point of
obstruction. With contrast injections and gentle torquing
23
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FIGURE 24-5. Examples of percutaneous urinary drainage catheters: Top: Percutaneous (PCN)
tube. The pigtail lies in the renal pelvis and external portion of the tube connects to a drainage
bag. Middle: Internal ureteral stent. One pigtail lies in the renal pelvis, and the other pigtail lies in
the bladder. The entire tube is inside the patient’s body. Bottom: Nephroureteral (NU) tube. The
pigtail at the end of the tube lies in the bladder, the central pigtail lies in the renal pelvis, and the
external portion of the tube can be capped off or connected to a drainage bag.
of the catheter, the guidewire usually can be advanced
beyond the obstruction without perforating the ureter,
even though the ureter appears to be completely occluded. Once the catheter and guidewire are in the bladder, the initial guidewire is replaced for a stiff guidewire,
which will support advancement of the stent. The stiff
guidewire must be advanced far into the bladder to allow
good “purchase.” If the bladder is not full, this maneuver
will be painful to the patient. A Foley catheter, if present,
should be clamped. The nephrostomy tract is dilated, and
the NU or ureteral stent can be inserted over the wire with
the distal pigtail positioned in the bladder and the proximal pigtail positioned in the renal pelvis.
When it is difficult to advance the stent over the stiff
guidewire, a few techniques will help “inch” the process
along. First, the bladder needs to be full, and as much
guidewire as possible needs to be in the bladder. The stent
will tend to creep downward when there is countertension
on the wire, that is, pulling back the wire as the stent is
being pushed forward. Second, introducing the stent
through a “peel-away” sheath usually corrects the difficulties resulting from a steep pushing angle and tightly strictured distal ureters. The peel-away sheath requires a separate step, a slightly larger hole in the kidney, and an
additional pieceof equipment. Third,the guidewire tip in
the bladder sometimes can be steered out the urethra,
more easily in women, or when there is a Foley in the
bladder. When the wire extends from the flank, through
the kidney, down the ureter, and out the bladder, both
wire ends can be held taut, thus easing the stent’s advancement down the ureter.
A “safety” wire is also useful to have in position when
performing complex manipulations or in less experienced hands. This safety wire is simply a second
guidewire placed alongside the first wire, known as the
working wire. If the working wire is inadvertently removed
from the collecting system, access will be preserved by
having the safety wire in place.
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