The RENAL score calculator for nephrectomy evaluates the complexity of renal tumors using an objective scoring system based on four inputs: renal mass radius, exophytic/endophytic properties, nearness of the tumor to the collecting system or sinus, and location relative to polar lines. Each of these inputs is assigned a score from 1 to 3 based on predefined categories, and the total score ranges from 4 to 12. This score determines the complexity of the nephrectomy and the associated risk of major complications.

The scoring system is as follows:

1. Renal mass radius, cm:
   - `<= 4`: 1 point
   - `4-7`: 2 points
   - `>= 7`: 3 points

2. Exophytic/endophytic properties:
   - `>= 50% exophytic`: 1 point
   - `< 50% exophytic`: 2 points
   - `Entirely endophytic`: 3 points

3. Nearness of the tumor to the collecting system or sinus, mm:
   - `>= 7`: 1 point
   - `4-7`: 2 points
   - `<= 4`: 3 points

4. Location relative to polar lines:
   - `Entirely above or below`: 1 point
   - `Crosses a polar line`: 2 points
   - `> 50% across the polar line, crosses the renal axial midline, entirely between the polar lines`: 3 points

To compute the total RENAL score, each input is matched with its respective score based on its category, then all scores are summed up.

Interpretation of the RENAL score is categorized as follows based on the total score:

- A score of `6 or less` indicates low complexity, with a 6.4% risk of major complications.
- A score from `7 to 9` indicates intermediate complexity, with an 11.1% risk of major complications.
- A score of `10 or more` indicates high complexity, with a 21.9% risk of major complications.

The RENAL score, also known as the RENAL Nephrometry Score, is a clinical calculator used in the field of urology. It is specifically designed for patients who are undergoing nephrectomy, a surgical procedure to remove all or part of a kidney. The RENAL score is used to assess the complexity of renal tumors, which can help guide treatment decisions and predict surgical outcomes. 

The score is based on five anatomical features of the tumor: Radius (tumor size), Exophytic/endophytic properties, Nearness of tumor to the collecting system or sinus, Anterior/posterior descriptor, and Location relative to polar lines. Each feature is assigned a score, and the total RENAL score ranges from 4 to 12. 

The RENAL score is not applicable to patients without renal tumors or those who are not candidates for nephrectomy. It also may not be as accurate in predicting outcomes for patients with multiple renal tumors.

RENAL score for nephrectomy