PARTIAL NEPHRECTOMY
Although radical nephrectomy is the standard surgical treatment for large renal tumors, nephron-sparing surgery has become the new standard of care for small (<4.0 cm) renal masses (SRMs).
In a partial
nephrectomy, the renal tumor and a small margin of normal tissue are removed.
The remainder of the parenchyma is spared, so as to preserve renal function.
Although partial nephrectomy offers benefits to all patients with SRMs, it is
especially beneficial for patients with multiple or bilateral masses, tumors in
a solitary kidney, or medical diseases that threaten future kidney function.
There is
substantial evidence that for tumors ≤4.0 cm in diameter, partial nephrectomy provides
oncologic outcomes that are comparable to those of radical nephrectomy. The
potential for tumor recurrence or progression to metastatic disease is low,
with 10-year cancer-specific survival rates between 87% and 90% in large patient
series.
Plate 10-22
OPEN PARTIAL NEPHRECTOMY: RETROPERITONEAL (FLANK) APPROACH
EVALUATION
The
preoperative evaluation should include basic laboratory tests (complete blood
count, serum chemistries, liver function tests), a chest radiograph, and
comprehensive axial imaging of the abdomen (either CT or MRI) with renal
protocols. Patients should receive counseling on all available management
options, which include active surveillance, partial nephrectomy, percutaneous
ablation (see Plate 10-24), and radical nephrectomy (see Plate 10-20). In
elderly patients or patients with significant medical comorbidities, ablation or
active surveillance are often more appropriate choices because of the high risk
of perioperative complications. Patients must be informed of the potential for
a planned partial nephrectomy to become a radical nephrectomy based on the
operative course.
TECHNIQUE
Partial
nephrectomy may be performed from either an open or laparoscopic approach. Both
techniques are equally effective for the treatment of a renal mass, but
laparoscopic partial nephrectomy is typically associated with less blood loss,
less pain, a lower risk of postoperative ileus, and a shorter hospitalization
and overall convalescence time. In addition, laparoscopic procedures require
smaller skin incisions, which yield better cosmetic results.
Both open
and laparoscopic partial nephrectomy procedures may be performed using
transperitoneal or retroperitoneal (flank) approaches. The different incision
sites, as well as the techniques for approaching the kidney, are the same as
described in the section on simple and radical nephrectomy (see Plate 10-21).
Once
visualized, the renal fascia should be mobilized free of its attachments and
then opened and dissected. The renal hilum should be carefully identified and
exposed. The tumor should be accurately localized using a combination of
high-quality preoperative imaging, intraoperative visualization, and
intraoperative ultrasonography (which establishes the location and depth of the
lesion in three dimensions). Using intraoperative color Doppler ultrasound, it should be confirmed that
occlusion of the renal vessels results in complete interruption of blood flow to
the tumor and surrounding parenchyma.
Once the
tumor has been characterized, intravenous mannitol should be infused to help
minimize renal ischemic injury during tumor excision. Mannitol increases renal
plasma flow, reduces intracellular edema, and promotes osmotic diuresis to flush
out debris and casts from
the renal tubules (see Plate 10-1).
Open Partial Nephrectomy
(OPN). Approximately 5 to 15 minutes after the administration of mannitol, the
renal artery and vein are clamped using atraumatic bulldog vascular clamps. An
ice-slush mixture is placed around the kidney for approximately 10 minutes so
that it is cooled to 20° to 25° C. This process reduces metabolic demands and
slows the consumption of oxygen, permitting up to 3 hours of renal artery
clamping without long-term ischemic damage.
Once cooling
is complete, the tumor is excised using a scalpel or Metzenbaum scissors,
allowing for a margin of normal parenchyma around the excised mass. The removal
of endophytic tumors often leads to collecting system injury, which requires
reconstruction using absorbable sutures. Bleeding is surgically controlled with
absorbable sutures. The bed of the cortical defect is cauterized using standard
electrocautery or an argon beam coagulator. Hemostatic agents are placed on the
parenchyma, and the renal capsule is closed using interrupted absorbable
sutures. The vascular clamps are then removed, hemostasis is confirmed, and the
surgical field is closed.
Laparoscopic
Partial Nephrectomy (LPN). Five to fifteen minutes after the administration of
mannitol, the renal artery is clamped using an atraumatic bulldog vascular
clamp. Renal parenchymal hypothermia remains a challenge during laparoscopic
partial nephrectomy because of the logistical challenges of introducing ice
into the field. Therefore, the renal vein is typically left patent, which may
help minimize ischemic damage by allowing retrograde perfusion of the kidney.
Excessive bleeding is usually not a concern because of the tamponade effect of
the pneumoperitoneum.
The tumor is
excised using laparoscopic scissors. Collecting system defects are repaired,
and the bed of the defect is cauterized. Any further bleeding is con- trolled
using absorbable sutures and hemostatic agents. The parenchymal defect is then
closed. The vascular clamps are removed, and hemostasis is again confirmed. The
pneumoperitoneum is reduced to ensure that bleeding does not occur without its
tamponade effect. The tumor is then removed intact in an entrapment bag, and
the trocar sites are closed.
Plate 10-23
LAPAROSCOPIC PARTIAL NEPHRECTOMY: TRANSPERITONEAL APPROACH
COMPLICATIONS
At present
there is no difference in complication rates between open and laparoscopic
partial nephrectomy. The most common postoperative complications are bleeding
and urine leak (urinoma).
In
situations where postoperative bleeding is suspected, the patient should be
managed with serial complete blood counts, bed rest, and blood transfusions as
needed. Conservative measures are often adequate when the bleeding is modest, but interventions such as selective arterial
embolization or surgical reexploration may sometimes be required.
Urine
leakage can result from inadequate intraoperative closure of a collecting
system defect or ureteral obstruction from a blood clot, which increases
backflow pressure. A surgical drain should therefore be used when the renal
collecting system has been violated to monitor for postoperative leak. In
addition, the patient should retain a Foley catheter to ensure bladder decompression and low
upper tract pressure. Urine leaks are usually transient and heal without
intervention; however, a persistent leak may require the placement of a
ureteral stent to facilitate drainage and healing.
In addition
to bleeding and urine leak, other potential complications include wound
infection, ileus, pneumonia, injury to adjacent organs, and transient renal insufficiency.
