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Introduction: Adherent perinephric fat (APF) increases the complexity of minimally invasive partial nephrectomy (MIPN). The Mayo Adhesive Probability (MAP) score can predict APF. Few data exist evaluating the impact of MAP score and APF on MIPN outcomes. We review an MIPN patient cohort to better define these associations.
Materials & Methods: 245 patients undergoing MIPN via laparoscopic (n=108) or robotic (n=137) techniques were included. APF was determined by keywords in operative notes. Radiographic data was obtained from pre-operative cross-sectional imaging. MAP score was calculated from posterior fat thickness and perinephric stranding. Posterior fat thickness was measured at the renal vein from the renal capsule to the posterior abdominal wall. Perinephric stranding was graded as 0 (none), 1 (mild), or 2 (moderate-severe). Logistic regression determined the association between MAP score and APF with clinical outcomes.
Results: 123 men and 122 women with a median age 55 years, BMI 31, tumor size 2.7 cm, and Nephrometry score of 6 were included. Median MAP score was 3 (range, 0 to 5), operative duration 208 minutes, and EBL 150 mL. 26 patients (10.6%) had APF. APF was associated with longer OR duration (p=0.006), greater EBL (p=0.02), and malignant renal histology (p=0.025) at MIPN (Table).
Conclusions: Increased MAP score and APF at MIPN are associated with several adverse outcomes. Further work is necessary to delineate the relationship with renal malignancy.

Associations between adherent perinephric fat and clinical and pathologic variables

Categorical Variable	No. pts (%) with APF	No. pts (%) without APF	p value
Renal cell carcinoma tumor histology	24 (92%)	156 (72%)	0.025
Complication	9 (35%)	55 (25%)	0.297
Major complication	2 (8%)	9 (4%)	0.612
Transfusion	0 (0%)	4 (2%)	1.000
Stage > T1	2 (8%)	12 (8%)	1.000
Fuhrman grade > 2	3 (13%)	22 (14%)	1.000
Positive margin	2 (8%)	7 (4%)	0.604
Continuous Variable	Median with APF	Median without APF	p value
OR duration	246 min.	207 min.	0.006
Estimated blood loss	200 mL	150 mL	0.02
Ischemia time	22.5 min.	21 min.	0.433
Change in GFR	-6.99 mL/min/1.73 m2	-8.03 mL/min/1.73 m2	0.815