TECHNIQUE OF PERCUTANEOUS ENDOPYELOTOMY
MATTHEW T. GETTMAN, JOSEPH W. SEGURA
Department of Urology, Mayo Clinic, Rochester, Minnesota, USA
ABSTRACT
Percutaneous endopyelotomy is an effective treatment for patients with ureteropelvic junction obstruction. This report describes the clinical presentation and preoperative evaluation for a patient with a UPJ obstruction. We describe the technical aspects of antegrade endopyelotomy in detail. The controversies regarding surgical technique and contraindications to treatment are presented. With percutaneous endopyelotomy, patients can expect up to a 90% success rate with little morbidity and minor disability.
Key words:
ureteropelvic junction, stenosis, endopyelotomy, percutaneous surgery
Braz J Urol, 26: 64-70, 2000
INTRODUCTION
Since
the introduction of percutaneous techniques initially for the treatment
of stones, the management of ureteropelvic junction (UPJ) obstruction
has radically changed. Dismembered pyeloplasty remains the gold standard
for treatment of UPJ obstruction, however minimally invasive procedures
in the properly selected patient can provide excellent success rates with
little patient morbidity. In comparison to other endoscopic treatments
for UPJ obstruction, percutaneous endopyelotomy has consistently achieved
success rates closest to those observed with open procedures (1-4). Patient
selection, however, is paramount to the success of any treatment for UPJ
obstruction (5). In this report we address patient selection, surgical
technique, possible complications, success rates, and controversies associated
with percutaneous pyelotomy.
The clinical presentation for patients with
UPJ obstruction is varied. Classically, patients with UPJ obstruction
present with flank pain often exacerbated by increased fluid intake and
evidence of obstruction on excretory urogram. In this situation, we proceed
to definitive treatment without additional investigation. For less straightforward
cases, we recommend additional testing that can include diuretic renograms,
diuretic urograms, or Whitaker pressure-perfusion tests. Retrograde pyelography
is sometimes obtained as the initial imaging test for patients with contrast
allergies. In other instances, retrograde pyelography is completed as
a confirmatory test prior to definitive treatment. We do not routinely
assess patients with a primary UPJ obstruction for presence of crossing
vessels. We do carefully review the imaging studies and laboratory reports
for other abnormalities such as marked hydronephrosis and poor renal function
as these factors can influence treatment outcome (1).
Other considerations, besides high-grade
hydronephrosis and poor renal function, can also influence treatment of
UPJ obstruction with percutaneous endopyelotomy. Long avascular strictures,
total obliteration of the UPJ, and severe periureteral fibrosis are contraindications
not only for percutaneous endopyelotomy but also for other endourologic
techniques (6). Other contraindications include an uncorrected bleeding
diathesis or untreated urinary tract infection. Patient age is not a contraindication
to treatment, although the patient must be a suitable candidate for either
regional or general anesthesia. Patient size also does not preclude use
of the procedure, however percutaneous endopyelotomy is less frequently
used in the pediatric age group for treatment of a primary UPJ obstruction.
Body habitus should be evaluated; the patient’s anatomy should be
such that percutaneous access is practical and safe. Furthermore, while
presence of a horseshoe kidney may not preclude an attempt at antegrade
endopyelotomy, (7) presence of a UPJ obstruction in other types of anomalous
kidneys is sometimes best treated with open techniques. In fact, little
information currently exists regarding use of any endourologic techniques
for treatment of a patient with a UPJ obstruction in a duplicated or ectopic
kidney (8). Use of antegrade endopyelotomy for patients with a secondary
UPJ obstruction is also not a contraindication, but details of the previous
procedure should be carefully reviewed prior to repeat surgery. Indeed,
treatment of secondary UPJ obstruction has been associated with success
rates at least equal to those observed with primary UPJ obstruction in
prior reports (9).
Clinical history and results of imaging
ultimately guide selection of the ideal patient for percutaneous endopyelotomy.
In our experience, we believe percutaneous endopyelotomy is the best treatment
when the UPJ is relatively dependent and no gross anatomic abnormalities
are present (5).
SURGICAL TECHNIQUE
Percutaneous
Access
Percutaneous endopyelotomy is completed
with the patient in the prone position. To minimize risk of infection,
all patients are given intravenous antibiotics prior to the procedure.
Percutaneous access to the renal pelvis is completed optimally through
an upper pole or middle pole calyx to aid visualization of the UPJ. After
obtaining access, a wire is placed in antegrade fashion under fluoroscopic
guidance across the UPJ obstruction, down the ureter, and into the bladder.
Alternatively, in situations where antegrade guidewire placement is difficult,
a guidewire can initially be placed in retrograde fashion. The guidewire,
placed in retrograde fashion, is then ultimately exchanged for a percutaneous
wire after dilation of the percutaneous tract.
Placement of a guidewire across the UPJ
obstruction is of critical importance since direct endoscopic vision of
the renal pelvis is often unreliable to identify a pinpoint UPJ that not
uncommonly is in an aberrant position. The percutaneous tract is dilated
to 28-F in preparation for nephroscopic examination of the renal pelvis.
During nephroscopic examination, the UPJ obstruction is inspected and
all blood clots are removed. If any stones are present, they are removed
prior to incision of the UPJ obstruction. If the guidewire was placed
initially in retrograde fashion, this wire is grasped with the forceps
and pulled through the nephroscope sheath. The wire is pulled out only
a sufficient distance to allow placement of an open-ended catheter over
the wire, across the UPJ, and down the ureter so that the open-ended catheter
extends from above the nephroscope sheath to about the midureteral position.
The original wire is then removed, and a new relatively rigid wire is
passed down the catheter through the ureter and into the bladder. The
wire that we prefer is a Lunderquist-Ring 0.038 torque wire. Since the
endopyelotomy is completed over this wire, careful attention should be
undertaken to prevent the wire from bending or kinking. In addition, the
wire should be positioned well into the bladder so that a double-J stent
is easily placed after endopyelotomy.
Endopyelotomy
At our institution, the endopyelotomy is
completed with the cold cutting knife. This endopyelotomy knife is commercially
available from Richard Wolf, Inc. and is designed for use in conjunction
with standard nephroscopy equipment. While the endopyelotomy knifes are
sharp when they arrive from the supplier, we recommend that the knives
be sharpened in the hospital machine shop prior to each use. The endopyelotomy
knife is passed over the working wire and is seen under direct vision
through the percutaneous nephroscope (Figure-1).
Before proceeding with the incision it is
important to determine if the UPJ is wide enough to accommodate the knife.
If the UPJ is not wide enough to accept the knife, the UPJ is balloon-dilated
so the knife can easily be passed through the UPJ. Gentle dilation of
the UPJ in this situation is critical so that ultimately the knife cuts
the UPJ smoothly rather than pushing the UPJ away. To decrease the likelihood
of tearing the UPJ during dilation, a 12F ureteral dilation balloon is
used rather than the larger 15F to 18F dilation balloons.
Placement of the endopyelotomy knife is
then completed to allow incision of the UPJ in the due-lateral position.
The lateral position is determined by orienting the knife to the lateral
position of the patient’s flank while referencing the position of
the kidney on the excretory urogram or CT scan. The orientation of the
cut is relatively easy to complete; however, in situations where the kidney
is malrotated the orientation of the cut can be more challenging. The
cut should also be made cautiously in patients that have previously undergone
a failed UPJ repair. In this situation the vascular supply of the kidney
relative to the UPJ may have changed. For example, if a patient previously
underwent a dismembered pyeloplasty, the vessels are usually transposed
posterior to the UPJ and the new cut should be made anteriorly.
After proper orientation, the knife is engaged
under direct vision along the curve of the guidewire to allow a smooth,
clean cut (Figure-2). Not uncommonly the guidewire will straighten as
the cut is made. The incision should extend down the ureter at least one
centimeter beyond the area of UPJ obstruction and should be continued
laterally up into the renal pelvis an additional one or two centimeters.
By performing the incision under direct vision, the operator can identify
the exact location and depth of the cut. In addition, extrapelvic structures
such as aberrant vessels, often visualized by pulsation, can be identified
and avoided. If significant bleeding is encountered at the time of the
incision, allowing clot to form in the renal pelvis with subsequent vascular
tamponade, typically controls hemorrhage. If arterial bleeding were to
persist despite these measures, embolization may be required.
The antegrade technique also allows for
the endopyelotomy incision to be extended under direct vision with excellent
precision. This ability is in contrast to blind techniques where the location
of a repeat cut cannot be exactly determined. A full thickness incision
of the renal pelvis and ureteral wall must be completed prior to removal
of the endopyelotomy knife. Fat or wispy retroperitoneal tissue is visualized
after completion of a full thickness cut (Figure-3). In patients undergoing
a second procedure, however, previous scarring can make determination
of the proper incision depth more challenging. While balloon dilation
is sometimes required to gently dilate the UPJ prior to endopyelotomy,
balloon dilation is not indicated following endopyelotomy.
Stent
Placement
Following completion of endopyelotomy, the
knife is carefully removed to prevent inadvertent removal of the guidewire.
Over the guidewire a double-J stent is placed. At our institution, we
use an 8.0/8.5F standard stent. The stent is placed over the guidewire
with a combination of fluoroscopic and visual control until the distal
curl is clearly seen within the bladder. We use a 26-cm stent for increased
flexibility in positioning the stent so that the distal curl is clearly
seen in the bladder.
Postoperative
Management
After placement of the double-J stent, a
22F nephrostomy tube is positioned in the renal pelvis. The nephrostogram
should reveal excellent drainage of the renal pelvis and some extravasation.
While the nephrostomy tube is commonly left indwelling for 48 hours, a
trial of tube clamping is completed prior to removal. If significant bleeding
is encountered upon removal of the nephrostomy tube, the nephrostomy tube
is immediately replaced and arteriography is arranged. The routine hospitalization
for most patients is 2-3 days, however some patients have been dismissed
much earlier. Most patients are able to return to normal activity one
week after surgery. Patients return six weeks from the time of surgery
for cystoscopic stent removal and an excretory urogram is completed three
months after surgery to further access the repair. All patients are then
followed at periodic intervals for signs or symptoms of late failure.
Percutaneous endopyelotomy is considered successful when the patient is
asymptomatic and the excretory urogram shows improved drainage (Figure-4).
COMMENTS
Percutaneous
endopyelotomy is a minimally invasive treatment with proven effectiveness
for patients with UPJ obstruction. Advantages of antegrade endopyelotomy
in comparison to open repair include shorter hospitalization, shorter
operating time, decreased disability, and quicker return to work (1-4).
While percutaneous endopyelotomy was initially offered to only patients
with secondary UPJ obstructions, today the procedure is considered increasingly
safe and effective for practically any patient with a UPJ obstruction
(1-4,6-9). For patients with primary UPJ obstructions, success rates of
76-90% have typically been reported (1-4). Although intuitively one would
expect that the treatment of failed previous repairs would be less successful,
the results reported in the literature for secondary UPJ obstruction are
similar to those reported for primary UPJ obstruction (8). Factors that
undoubtedly influence the success of percutaneous endopyelotomy include
the anatomic characteristics of the patient population, the surgeon’s
comfort level with the procedure, and postoperative surveillance protocols.
Indeed, whereas some clinicians gauge success of treatment on the basis
of symptom improvement and appearance of postoperative excretory urography,
other clinicians rely on more objective criteria to gauge treatment success
(5).
Treatment failure generally becomes evident
in the early postoperative period. Gupta et al. have reported only 8%
of treatment failures occur after the first postoperative year (1). Kletscher
et al. similarly reported all observed treatment failures at our institution
occurred within the first 2 months after surgery (3). Long-term surveillance
is required, nonetheless, as late failures do occur (5,6). The range of
late failure rates and predisposing risk factors are poorly understood.
Whereas the importance of crossing vessels is controversial, there is
general agreement that marked hydronephrosis and poor renal function impact
on the failure rate (1,6). Indeed, for patients with marked hydronephrosis,
the physiology of the renal pelvis may still be abnormal and contribute
to failure for some of these patients following endopyelotomy.
While antegrade endopyelotomy is associated
with little patient morbidity, a variety of complications can be associated
with the procedure. As with any surgical procedure, all patients are at
risk for bleeding, infection, and anesthesia complications. The urologic
complications of antegrade endopyelotomy in general fall into two categories:
those related to percutaneous access and those directly related to the
endopyelotomy. As with percutaneous stone surgery, the complications related
to percutaneous access are frequently more varied and often more severe.
Vascular injuries resulting in significant bleeding are the most worrisome
complications associated with endopyelotomy (10). These injuries can occur
during dilation of the percutaneous tract or during incision of the UPJ.
The transfusion rates associated with percutaneous endopyelotomy vary
from 1-6% (1-4,6,7,9). As the time required to complete endopyelotomy
is shorter, complications related to fluid absorption are typically decreased.
The incidence of urosepsis associated with endopyelotomy is 2-4% (10).
Other previously reported rare complications unique to endopyelotomy include
ureteral necrosis, ureteral avulsion, urinoma, inadvertent incision of
the renal pelvis, and stent migration (10).
Despite excellent results and low overall
morbidity, controversy does exist regarding various technical aspects
of percutaneous endopyelotomy. With the introduction of spiral CT and
endoluminal ultrasound, some investigators have stressed a preoperative
evaluation for crossing vessels, whereas other investigators have not
routinely favored this approach (1-3). In a recently reported series of
401 patients undergoing antegrade endopyelotomy, crossing vessels were
attributed to only 4% of treatment failures, while extrinsic fibrosis
was the most common cause of failure (1). Additional imaging studies may
possibly improve the surgical approach to patients with ectopic or malrotated
kidneys and to patients with secondary UPJ obstructions.
The method and orientation of the UPJ incision
is also debatable. While we prefer use of the cold knife for endopyelotomy,
others have reported equivalent success rates with other techniques including
laser and electrocautery (5). We believe the surgeon has less control
of the depth of the incision when using the Bugbee electrode rather than
the cold knife. Previous reports have also suggested the risk of vascular
injury may be increased with use of electrocautery (10). Based on the
work of Sampaio et al. regarding the location of crossing vessels, we
now advocate use of a lateral incision rather than a posterolateral incision
(11). Obviously, the orientation of the incision is even more controversial
when faced with treating an ectopic kidney, malrotated kidney, or secondary
UPJ obstruction.
The issue of stenting has also been controversial.
Initially a 14/ 7-F endopyelotomy stent was favored following the procedure.
These stents were very difficult to place in the previously unstented
ureter and did not appear to improve the success rate (3,5). Currently,
the trend is to use smaller-caliber stents that are less expensive and
easier to place. While many have recommended leaving a stent indwelling
for 6 weeks after endopyelotomy, (1-3) other groups have removed stents
earlier without untoward results at least in short-term follow-up (4).
Percutaneous endopyelotomy has become a
procedure of choice for many patients with UPJ obstruction. Overall success
rates up to 90% can be expected in a wide range of carefully selected
patients (1-4,6-9). By avoiding patients with uncorrected bleeding diathesis,
untreated infection, and anatomic abnormalities precluding safe access,
percutaneous endopyelotomy is a safe, effective treatment for patients
with UPJ obstruction that is associated with limited disability and minimal
morbidity. As similar results have been noted for patients undergoing
endopyelotomy with a variety of subtle technical differences, likely no
specific technique of percutaneous endopyelotomy is superior and the primary
factors determining success of the procedure are appropriate patient selection
and effective release of the UPJ obstruction.
REFERENCES
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- Kletscher BA, Segura JW, Patterson DE: Percutaneous antegrade endopyelotomy: review of 50 consecutive cases. J Urol, 153: 701-703, 1995.
- Motola JA, Badlani GH, Smith AD: Results of 212 consecutive endopyelotomies: an 8-year followup. J Urol, 149: 453-456, 1993.
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- Bellman GC, Yamaguchi R: Special considerations in endopyelotomy in a horseshoe kidney. Urology, 47: 582-586, 1996.
- Jabbour ME, Goldfischer ER, Stravodimos KG, Klina WJ, Smith AD: Endopyelotomy for horseshoe and ectopic kidneys. J Urol, 160: 694-697, 1998.
- Jabbour ME, Goldfischer ER, Klima WJ, Stravodimos KG: Endopyelotomy after failed pyeloplasty: the long-term results. J Urol, 160: 690-693, 1998.
- Bellman GC: Complications of endopyelotomy. J Endourol, 10: 177-181, 1996.
- Sampaio FJB, Favorito LA: Ureteropelvic junction stenosis: vascular anatomical background for endopyelotomy. J Urol, 150: 1787-1791, 1993.
______________________
Received: August 25, 1999
Accepted: September 1, 1999
_______________________
Correspondence address:
Joseph W. Segura, M.D.
Mayo Clinic, Department of Urology
Mayo Building, East 17A
200 First Street, S.W.
Rochester, Minnesota, USA, 55905
Fax: (0021) 1 507 284-4987
E-mail: segura.joseph@mayo.edu