Purpose: To compare outcomes of two different miniaturized percutaneous nephrolithotomy (PCNL) techniques: minimally invasive PCNL (MIP) with the vacuum cleaner effect and vacuum-assisted mini-PCNL (vmPCNL). Materials and Methods: Data from 104 (66.7%) patients who underwent vmPCNL and 52 (33.3%) patients who underwent MIP at a single tertiary referral academic center between January 2016 and December 2019 were analyzed. Patient demographics and peri-and postoperative data were recorded, and propensity score matching was performed. Descriptive statistics and linear regression models were used to identify variables associated with operative time (OT) and patient effective dose. Logistic regression analyses were used to identify factors associated with infectious complications and stone-free (SF) status. Results: Patient demographics and stone characteristics were comparable between groups. vmPCNL was associated with shorter OT ( p < 0.001), fluoroscopy time, and patient effective dose (4.2 mSv vs 7.9 mSv; p < 0.001). A higher rate of infectious complications was found in the MIP group (25.0% vs 7.7%, p < 0.01). Linear regression analysis showed that stone volume, multiple stones, and MIP procedure (all p values £0.02) were associated with longer OT. Similarly, OT and the MIP procedure ( p £ 0.02) were associated with higher patient effective dose. Logistic regression analysis revealed that the stone volume, positive preoperative bladder urine culture, and MIP procedure (all p values £0.02) were associated with postoperative infectious complications. vmPCNL was not associated with the SF rate. Conclusions: Mini-PCNL performed with continuous active suction is associated with lower rates of infectious complications, shorter OT, and lower patient effective dose than MIP.

Purpose To describe the vacuum-assisted mini-percutaneous nephrolithotomy (vmPCNL) technique performed via the 16Ch ClearPetra sheath, to evaluate its outcomes and to analyze intrarenal pressure (IRP) fluctuations during surgery. Methods Data from all consecutive vmPCNL procedures from September 2017 to October 2019 were prospectively collected. Data included patients' and stones characteristics, intra and peri-operative items, post-operative complications and stone clearance. Patients undergoing vmPCNL from March to October 2019 were submitted to IRP measurement during surgery. Results A total of 122 vmPCNL procedures were performed. Median stone volume was 1.92 cm 3. Median operative time was 90 min and median lithotripsy and lapaxy time was 28 min. Stone clearance rate was 71.3%. Thirty-one (25.2%) patients experienced post-operative complications, seven of which were Clavien 3. Postoperative fever occurred in nine (7.4%) patients and one (0.8%) needed a transfusion. No sepsis were observed. IRPs were measured in 22 procedures. Mean IRP was 15.3 cmH 2 O and median accumulative time with IRP > 40.78 cmH 2 O (pyelovenous backflow threshold) was 28.52 sec. Maximum IRP peaks were reached during the surgical steps when aspiration is closed (mainly pyelograms), whereas during lithotripsy and suction-mediated lapaxy, the threshold of 40.78 cmH 2 O was overcome in three procedures. Conclusions vmPCNL is a safe procedure with satisfactory stone clearance rates. Mean IRP was always lower than the threshold of pyelo-venous backflow and the accumulative time with IRP over this limit was short in most of the procedures. During lithotripsy and vacuum-mediated lapaxy, IRP rarely raised over the threshold.