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Parra et al. Mini-invasive Surg 2024;8:16 https://dx.doi.org/10.20517/2574-1225.2024.01 Page 3 of 13

Surgical technique
Despite small differences in technical details between surgeons, our surgical technique involves
transperitoneal laparoscopic access with four trocars (11, 12, 5, and 5 mms). The retroperitoneum access is
performed through the Told’s line, moving the bowel segment to the middle line. Then, the Psoas muscle is
identified as a landmark to find the ureter and the gonadal vein at the level of the lower renal pole, which
are dissected in an ascending way until we locate the renal hilum [Figure 1]. Dissection of the renal artery
and vein and referral with vessel loop of the artery (or arteries) is performed. Subsequently, the renal tumor
is located, dissecting the Gerota fascia and removing the fat surrounding the kidney as much as necessary
for tumor resection and subsequent suturing of the renal bed. We mark the circumference of the tumor
[Figure 2], and arterial clamping is performed if it is thought to be necessary, either from the main renal
artery or from a branch directed toward the tumor [Figure 3]. We usually perform the tumor enucleation to
preserve as much renal parenchyma as possible [Figure 4]. Immediately afterward, suturing is started, first
in the deep plane of the bed to ensure the water-tightness of the urinary tract (in case of opening) and
closure of deep vessels, and then another upper renorrhaphy, including the renal parenchyma [Figure 5].
The clamp (Bulldog) is then removed from the artery, and hemostasis is checked. The usage of cellulose-
type hemostatic material is optional [Figure 6]. Lastly, the perirenal fat is then sutured if feasible. We leave a
drain in the surgical bed, and we close the skin wounds.

Patients, clinical parameters, statistical analysis
A careful selection of patients was carried out. The inclusion criteria were as follows: all patients were
operated on in our center by PN or tumorectomy, either robotic or laparoscopic, of any age, due to a renal
mass. Patients whose surgery was turned into open surgery were excluded from the analysis.

We studied clinical, perioperative and histopathological variables together with oncological and functional
outcomes. The different preoperative variables studied were sex, age, Charlson index, body mass index
(BMI), smoking, GFR before surgery and laterality. As perioperative variables, we selected: intraoperative
complications, postoperative complications, need for ischemia and hospital stay. As follow-up variables, we
selected: GFR 1st day after surgery and GFR after 6 months.

After surgery and during the hospitalization period, a blood test was performed to assess creatinine (ng/dL)
2
and GFR estimation (mL/min/1.73 m ) on the first and third day. After discharge, a close follow-up of the
patient was established, with a review and renal function analysis at three and 6 months and then at one
year.

We will describe the data obtained with mean and median with their respective standard deviations and
interquartile ranges. We divided the patients into three groups depending on the ischemia time (1: zero
ischemia; 2: ischemia < 20 min; and 3: ischemia ≥ 20 min). Using Pearson’s chi-square test, we analyzed the
relationship between different comorbidities such as hypertension and diabetes mellitus as well as the
Charlson index with the eGFR after surgery. We performed a hypothesis test using the analysis of variance
(ANOVA) test to see if there was a relation between tumor complexity (R.E.N.A.L. score) and the necessity
of arterial clamping reflexed with the three named groups (1: zero ischemia; 2: ischemia < 20 min; and 3:
ischemia ≥ 20 min), with subsequent multivariate analysis. Finally, we rated the relationship between
ischemia time and short- and long-term renal function, respectively, the first day after surgery and after 6
months.

Evidence acquisition for discussion
We piloted complete English language literature research for original and review manuscripts using the
Medline database and literature through June 2023. We searched for the following terms: partial