Adherent perinephric fat at minimally invasive partial nephrectomy is associated with adverse peri‐operative outcomes and malignant renal histology

Abstract

A total of 245 patients undergoing MIPN were included in the study. The presence of APF was determined through keywords in operating notes, and radiographic data were obtained from preoperative cross-sectional imaging. Posterior fat thickness was measured between the renal capsule and the posterior abdominal wall at the level of the renal vein. Perinephric stranding was graded on a 0-3 severity scale. ResultsThe study included 123 men and 122 women, with a median age of 55 years, body mass index of 31.7, tumour size of 2.7 cm and nephrometry score of 6. The median posterior fat thickness was 1.79 cm and MAP score 2.63. In all, 26 patients (10.6%) had evidence of APF at the time of renal surgery. Factors predictive of APF included increasing age (P = 0.001), male gender (P = 0.045), perinephric stranding (P = 0.002), posterior fat thickness (P < 0.001) and MAP score (P < 0.001). APF was associated with adverse pathological and peri-operative outcomes including malignant renal histology (P = 0.04), longer operating time (P = 0.005) and greater estimated blood loss (EBL; P = 0.025). ConclusionsSpecific clinical and radiographic factors predict APF at MIPN. The presence of APF is associated with adverse perioperative outcomes including longer operating time and greater EBL. APF was also associated with renal malignancy on final pathology, but further studies are necessary to elucidate the precise underlying mechanism.

Adherent Perinephric Fat in Asian Patients: Predictors and Impact on Perioperative Outcomes of Partial Nephrectomy

“…The incidence of APF in our study was 17%, which was lower than the incidence rates in previous studies of Western cohorts (30-55%) [3,4,6,13]. BMI was associated with APF in this Asian cohort as it was in the Western cohorts, although the mean BMI (24 kg/m 2 ) in our study was smaller than those in Western studies (29-33 kg/m 2 ) [5,6,12]. Since Asians tend to have higher percentages of body fat than Caucasians do at equivalent BMIs [7,8], it could be supposed that the incidence of APF in Asians is close to that in Caucasians, in spite of the difference in their mean BMIs.…”

“…The current results showed, however, that Asians had a lower incidence of APF at lower BMI levels compared to Caucasians. The predictors of APF other than MAP score reported in the Western cohorts were male gender, older age, obesity, waist circumference, and hypertension [3][4][5]. The current study indicated that male gender was a strong predictor of APF in multivariate analysis, although other metabolic factors, including older age, higher BMI, smoking habit, and history of hypertension were not associated with the presence of APF.…”

“…During PN DOI: 10.1159/000494068 procedures, surgeons sometimes encounter sticky fat around the renal parenchyma which has been designated as adherent perinephric fat (APF). The presence of APF can increase the difficulty of tumor identification and exposure, and is associated with longer surgery duration and greater blood loss [3][4][5]. Therefore, the ability to predict the presence of APF before PN would be helpful, and it could help determine the surgical approach offered to each patient.…”

“…In that study, body mass index (BMI), male gender, and radiological findings were associated with APF, and a risk score was created according to radiological findings that were the only independent predictors of APF in multivariate analysis. MAP score is an accurate method of predicting APF, and it has been validated in several Western cohorts [3][4][5].…”

Two‐dimensional shear wave elastography of the perirenal fat: Can sticky fat be predicted?

“…PSF is defined as thick and adherent perirenal fat (PF) that is difficult to dissect off the renal capsule and is well known to experienced urologists who are involved with partial nephrectomy (PN). It has been related to longer operating time, increased perioperative complications and conversion to open surgery . Currently there is no validated imaging marker to predict the presence of PSF and there is only a limited number of studies in the literature evaluating the prediction of PSF by preoperative imaging which all relied on CT or MRI for PF characteristics.…”