Results
Mean age of the patients was 51.3±12.7 years and the male to female ratio was 34:28. Mean BMI was 28.6± 5.2; among the 62 patients, 23 were overweight and 26 were obese. In total, 3/62 patients had diabetes mellitus, 15/62 had hypertension, and 2/62 were smokers. Among the patients, 90.3%(n=56/62) were light workers. Among the 22 partial nephrectomies, 17(77.3%) were performed via an open approach and 5(22.7%) were performed laparoscopically. All 40 donor nephrectomies were performed laparoscopically, of which 36/40(90%) were hand assisted. Most of the nephrectomies were performed on the left side(52/62). Mean tumor diameter was 35.8±16.7mm(n=22).
The distribution of cases according to dissection complexity was as follows: easy: n=27(43.5%); moderate: n=20(32.3%); difficult: n=15(24.2%). Mean perirenal fat dissection time was 15.0±13.5 min. Mean dissection time in the cases with easy, moderate, and difficult dissection complexity was 5.6±2.9, 12.7±2.1, and 35.1±13.0min respectively. Dissection complexity classification(as easy, moderate and hard) was in correlation with the time required for the dissection(p<0.05).
There wasn’t a significant difference in perirenal fat dissection complexity between the male and female patients(p=0.074). Similarly, correlations between weight, height, and BMI were not significant. Moreover, there wasn’t a correlation between perirenal fat dissection complexity, and surgical side, the presence of diabetes mellitus, the presence of hypertension, smoking status, or occupational status(p>0.05).
The was a significant difference in perirenal fat dissection complexity between open and laparoscopic nephrectomies(p<0.05); most of the difficult dissection complexity cases underwent open surgery. Subcutaneous fat thickness measured intra-operatively did not differ according to dissection complexity(p=0.87); however, intra-operative measurement of perirenal fat thickness and dissection complexity were significantly correlated, such that median perirenal fat thickness was lowest in the cases with easy dissection complexity(median: 10,4-20) group and highest in those with difficult dissection complexity(median: 17, 10–28, p<0.05).
Radiological findings showed that there was a significant relation between perirenal fat depth and perirenal fat dissection complexity; thewith a higher difference was greatest in the difficult dissection complexity patients(p<0.05); however, HU for the perirenal field and subcutaneous fat measured via CT showed that there wasn’t a significant difference according to dissection complexity(p=0.88 and p=0.52, respectively). The radiologically measured perirenal fat depth and intra-operative measurement of perirenal fat thickness were significantly correlated (r=0.363, p=0.005).
Perinephric fat exhibited evidence of histological fibrosis more commonly in the patients with severe APF(Table). All 4 parameters that we explored for fibrosis were higher in the patients with difficult dissection complexity. The median thickness of Gerota’s fascia at its thickest part was 251µm (range:80-716µm) in the patients with easy dissection complexity, versus 196µm(range:67.6-652µm) and 384.5µm(range:151-910.4µm) in those with moderate and difficult dissection complexity, respectively(p=0.006). In all, 8(34.8%) of the 23 patients with easy dissection complexity, 5(29.4%) of the 17 with moderate dissection complexity, and 12(80%) of the 15 with difficult dissection complexity had perivascular fibrosis(p=0.007). Intercellular collagen accumulation was observed in 8.7% (2/23) of the patients with easy dissection complexity, 11.8%(2/17) of those with moderate dissection complexity, and 80%(12/15) of those with difficult dissection complexity(p=0.000).
Spicules or bands of collagen radiating from the outer fascia, interlobular septae, and perivascular fibrous tissue were more common in the patients with APF(22%, 47%, 87% in the easy, moderate, and difficult dissection complexity patients, respectively, p=0.000). There weren’t any significant differences in inflammation, or mean and maximum adipocyte diameter according to perirenal fat dissection complexity. Fat tissue in the severe APF patients contained a higher number of blood vessels with wall thickness >100µm(p=0.039). There wasn’t a significant difference in small capillary density according to perirenal fat dissection complexity(p>0.05).