Partial Nephrectomy Workup

Updated: Apr 01, 2019
  • Author: Reza Ghavamian, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Workup

Laboratory Studies

Routine preoperative laboratory studies, including complete blood cell count, electrolyte assessment, blood urea nitrogen, and creatinine assessment, are obtained. Note the following:

  • Although no set level of serum creatinine precludes nephron-sparing surgery (NSS), the patient's baseline renal function is important. Not all patients with chronic renal insufficiency (CRI) require renal replacement therapy in the short term, and many can be treated medically for long periods.

  • Radical nephrectomy can place the patient in need of immediate renal replacement therapy. If anatomically feasible, NSS can delay the onset of dialysis without compromising cancer care in the properly selected patient with CRI.

The patient's blood should be typed and cross-matched.

Other blood tests may include liver function tests and serum ferritin assessment, although tests to detect metastases are not always necessary in the small, incidentally detected mass that is amenable to partial nephrectomy.

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Imaging Studies

With the advent of modern imaging modalities, most renal cell carcinoma (RCC) is detected incidentally during CT scan performed with and without intravenous contrast or abdominal ultrasonography. Intravenous urography may not clearly define a small renal mass; therefore, other forms of confirmatory imaging are frequently required.

The size, location, and characteristics of the renal mass (cystic vs solid) are assessed adequately with ultrasonography, CT scanning, and magnetic resonance imaging (MRI) of the abdomen. Note the following:

  • CT scanning and MRI of the abdomen can be beneficial to rule out metastatic or locally extensive disease.

  • MRI also has a role in evaluating the inferior vena cava for the presence of tumor thrombus and its proximal and distal extent. Magnetic resonance angiography (MRA) also allows for excellent definition of the vascular anatomy and the segmental vascular anatomy for optimal surgical planning.

Some surgeons have used intraoperative ultrasonography for evaluation of multifocality in select cases when preoperative imaging studies are equivocal or intraparenchymal nonpalpable tumors are suggested. Intraoperative ultrasonography can be a valuable adjunct in this setting. Its use is associated with a learning curve; however, this can be overcome with the aid of a radiologist or frequent use of the modality.

Inferior and superior venacavography are not generally needed in the era of modern imaging. Furthermore, preoperative imaging modalities must delineate the relationship of the tumor to the normal surrounding parenchyma to allow for safe and adequate tumor excision while preserving maximal normal renal parenchyma.

Although not essential in small peripherally located tumors, preoperative evaluation of the vasculature of the kidney and the tumor can aid in tumor excision. This is especially true of larger lesions and those that occupy a more central position close to the renal hilum, especially in a solitary kidney. In the past, renal angiography was used routinely to delineate vasculature. In the modern era, less invasive modalities, such as MRA, can be used to define anatomic relationships preoperatively.

In addition, the use of 3-dimensional helical CT scan has provided important anatomical information concerning the renal vasculature and excretory function of the affected kidney. This technique better defines the relationship of the tumor with the collecting system and renal vasculature for preoperative surgical planning. In addition, it helps to anticipate tumor extension further so that operative complications can be minimized while obtaining the maximum surgical outcome. Small cuts through the tumor can be generated and the 3-dimensional reconstruction can aid in the surgical planning.

In the unusual case in which the above studies fail to provide adequate imaging, conventional renal angiography can be of considerable value. Oblique views of the kidney may further delineate the segmental arteries. An important component of renal angiography is the venous phase of the study. Complete delineation of the renal arterial and venous vasculature is essential in the setting of a centrally located tumor in a solitary kidney.

Chest radiography is indicated as a routine preoperative test.

The role of PET scanning in RCC is not well established, although its role has been studied to a limited extent. The extent to which it can help in the identification of limited nodal disease is not well known. However, it has been used for monitoring the response to therapy (to interleukin-2) of the original tumor and metastatic sites. It may allow for the identification of appropriate marker lesions for further monitoring of therapy and can be yet another way to characterize tumors in patients with a complete response.

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Diagnostic Procedures

A dilemma exists with respect to the nature of the solid lesion prior to planned surgery. In a recent prospective study, 103 patients diagnosed with a solid renal mass on CT scan and scheduled for surgery were evaluated. [2]  Note the following:

  • At the time of surgery, a biopsy sample of the surgical specimen was obtained under direct vision. Frozen section biopsy samples were compared to whole tissue specimens and reviewed by 2 pathologists.

  • These experienced pathologists were able to diagnose only 3 out of 4 cases based on frozen section findings.

  • Although the positive predictive value was excellent (94%), a large degree of inaccuracy existed for benign lesions, and many biopsy samples (approximately 22%) were nondiagnostic.

  • The authors do not recommend routine use of intraoperative frozen section needle biopsy to guide surgical decision making. Percutaneous image-guided biopsies still have a role, especially to help rule out metastatic lesions. The information presented is clear evidence that, even under ideal biopsy circumstances, needle biopsy is insufficiently accurate (75%) in defining the nature of small renal lesions. For this reason, NSS with complete excision plays an important role for the small incidentally detected tumor because biopsy findings frequently do not change the surgical management.

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