The RENAL nephrometry scoring system was developed to categorize renal masses into low, intermediate and high complexity, based on cross-sectional imaging findings. Its purpose is to aid in decision making, patient counseling, surgical planning, and patient follow-up, as well as academic reporting.
Classification
Scoring is based on five basic radiological features of the mass (see "Scoring" below). This score was originally developed for renal masses based on MDCT features utilizing a CT IVU protocol but can also be calculated from MRI features.
Scoring
RENAL is actually an easy-to-remember acronym (i.e. mnemonic) of the five features scored, as follows:
-
Radius (maximum diameter) in centimeters (cm) in any axis:
- ⩽4: 1 point
- >4 but <7: 2 points
- ⩾7: 3 points
-
Exophytic/endophytic tumor location:
- ⩾50% exophytic: 1 point
- <50% exophytic: 2 points
- 100% endophytic: 3 points
-
Nearness to the renal collecting system or renal sinus measured in millimeters (mm) as the shortest distance from the deepest point of the tumor:
- ⩾7: 1 point
- >4 but <7: 2 points
- ⩽4: 3 points
-
Anterior or posterior location - assessed on the axial view:
- no points are allocated
- descriptors: “a” (anterior), “p” (posterior) or “x” (neither)
- Location relative to the renal poles
- entirely below the inferior pole or above the superior pole: 1 point
- mass crosses the polar line: 2 points
- >50% of mass lies across the polar line or is entirely between the polar lines or crosses the axial midline: 3 points
- h: assigned as a suffix if the mass touches the main renal artery or vein
Nephrometry score grading
- score of 4-6: low complexity
- score of 7-9: moderate complexity
- score of 10-12: high complexity
History and etymology
Alexander Kutikov and Robert G Uzzo, American urologists working at Temple University School of Medicine, in Philadelphia, USA, published their scoring system in 2009 3.
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