The RENAL nephrometry score provides a standardized, quantifiable method to classify renal masses based on their anatomic complexity using 5 factors: Radius (R), Exophytic/endophytic (E), Nearness of tumor to collecting system (N), Anterior/posterior (A), and Location relative to polar lines (L). Masses are stratified into low, medium, and high complexity scores which correlate with surgical difficulty, oncologic outcomes, and treatment approach. The score informs surgical decision making such as open vs minimally invasive surgery or active surveillance vs intervention.

1. RENAL NEPHROMETRY SCORING

2. • The RENAL Nephrometry Score was developed as
a standardized system to objectify reporting of
critical anatomical features of a renal mass.
• Provides a quantifiable and reproducible method
to classify renal masses according to anatomic
complexity.
• Stratifies masses into low, medium, and high
complexity, with increasing complexity
correlating with more aggressive tumor biology,
more challenging resectability via nephron
sparing surgery, and clinical outcomes.

3. • The RENAL nephrometry score is based on the
five most reproducible features that characterize
the anatomy of a solid renal mass on contrast-
enhanced cross-sectional imaging.

5. • The “R” descriptor represents the maximum
diameter of the mass.
• Lesions ≤ 4 cm are assigned 1 point,
• > 4 but < 7 cm are assigned 2 points,
• ≥ 7 cm are as-signed 3 points.
Assess coronal and sagittal views, not just axial.

6. • The “E” descriptor denotes the exophytic or endophytic
location of the tumor. Lesions that are predominantly
endophytic pose a greater surgical challenge than those
that are exophytic.
• Lesions that project more than 50% outside the renal
cortex are assigned 1 point,
• Less than 50% are assigned 2 points,
• Entirely endophytic are assigned 3 points
Not all masses are symmetrical. Use the most predominant
feature in any axis.
Measure from where normal parenchymal edge should be if
no tumor were present (masses often distort normal
renal parenchymal contour). Compare distance from
normal parenchymal edge location to most endophytic
and most exophytic portions of the tumor.

7. • The “N” descriptor denotes the proximity to the
collecting system measured in millimeters and is
best determined on excretory images. As with the
“R” descriptor, the point scale is divided between
values of 4 and 7 using millimeters rather than
centimeters.
• Tumors again are divided into three categories:
• 7 mm or greater from the collecting system or renal
sinus (1 point),
• tumors > 4 but < 7 mm (2 points)
• tumors 4 mm or less from the central collecting
system (3 points)
Measure from deepest portion of the tumor (in any
plane) to renal sinus or collecting system.

8. • The “A” descriptor indicates the anterior or posterior
location of the tumor
• Not assigned a point value.
• If the tumor lies primarily on the ventral surface of
the kidney the anterior (a) descriptor is assigned.
• Tumors located on the dorsal renal surface are
assigned a posterior (p) designation.
• Tumors that do not fall into one of these categories,
such as a purely lateral or a central apical lesion, are
assigned the designation “x”
Assess in axial view. Draw a line paralleling renal hilar
structures bisecting the kidney

9. • The “L” descriptor defines the location of the tumor with respect to the
polar lines.
• The superior and inferior polar lines are defined by the renal vascular
pedicle and can be determined on either axial or coronal images.
• Tumors that sit entirely above or below the polar boundaries are
assigned a score of 1;
• If the lesion crosses the polar line, a score of 2 is assigned;
• If > 50% of the mass crosses the polar line or the mass is located
entirely between the polar lines, as score of 3 is assigned.
• Lesions that abut the main renal vein or artery are given the suffix “h”
to define the hilar location. This “h” designation does not impact the
score.

10. • The Nephrometry Score Grading
• Using the scoring system, tumor complexity is
determined:
• low complexity (nephrometry score = 4–6),
• moderate complexity (nephrometry score = 7–9),
• high complexity (nephrometry score = 10–12)

11. Why Use ?
• Standardizes reporting of renal tumor size, depth,
and location.
• Informs surgical decision-making and effectively
compares masses in practice and in the literature.
• Allows for accurate communication regarding
complexity of masses (e.g. when consulting with
specialists before images are sent).
• Validated to predict likelihood of surgical
complications, perioperative clinical outcomes, high
grade pathology, and case selection (partial versus
radical nephrectomy).
• The most consistently used and extensively validated
score in the urologic literature.

12. • Impact of RENAL score on surgical decision-
making:
– Partial Nephrectomy vs Radical Nephrectomy: Higher
complexity score more likely to undergo RN.
– Minimally Invasive Surgery vs. Open: High complexity
scores more likely to undergo open surgical
approaches.
– Active surveillance vs. intervention: High complexity
score more likely to undergo surgical intervention.