Micropercutaneous Nephrolithotomy Research Articles

Factors predicting outcomes of micropercutaneous nephrolithotomy: results from a large single‐centre experience

To present our single-centre experience of the micropercutaneous nephrolithotomy (microperc) technique and define its role in the management of renal calculi as well as to analyse the factors predicting outcome. We retrospectively analysed data from 139 patients who underwent microperc for renal calculi between June 2010 and November 2014 at our institution. The factors analysed were demographic variables, which included age, sex, stone volume, stone density (Hounsfield units [HU]) and stone location, and intra- and peri-operative variables, such as operating time, drop in haemoglobin level, stone clearance and complications. The mean ± sd (range) patient age was 38.99 ± 17 years (9 months to 73 years), stone volume was 1 095 ± 1 035 (105-6 650) mm(3) and stone density was 1 298 ± 263 HU. The mean ± sd (range) operation duration was 50.15 ± 9.8 (35-85) min, hospital stay was 2.36 ± 0.85 (2-5) days and drop in haemoglobin level was 0.63 ± 0.84 (0-3.7) mg/dl. Eight patients had renal colic that was managed by antispasmodic medication, four patients had renal colic severe enough to warrant JJ stenting and three patients had urinary tract infections which were managed with appropriate antibiotics. We were able to complete microperc in 130 patients, with 119 (91.53%) patients being rendered completely stone-free, while in 11 patients (8.46%) there were some residual fragments seen on imaging. On multivariate analysis, stone number, volume and density were found to be significant predictors of clearance. Conversion to mini- or standard percutaneous nephrolithotomy was required in nine patients (6.47%), with intra-operative complications and stone number being the significant factors warranting conversion on a multivariate basis. The outcomes in the present study suggest that microperc is a promising treatment method for solitary renal stones with volumes <1 000 mm(3) and stones with low density (HU), regardless of stone location. In the present series we achieved a high success rate with low morbidity; however larger, prospective and comparative studies from multiple centres are required to further establish the role of microperc in the management of renal calculi.

Micro-percutaneous nephrolithotomy in the treatment of pediatric nephrolithiasis: A single-center experience

ObjectiveWe aimed to clarify the applicability and safety of micro-PNL (microperc) in the treatment of pediatric kidney stones. Material and methodsA single center prospective trial was initiated, and microperc was performed in 40 children using the same two methods: the classical all-seeing needle and microsheath method. Stone fragmentation was performed using a 200-μm holmium:YAG laser fiber. ResultsThe mean age of the patients was 6.3±4.4years (range: 7months–16years). Fourteen were less than 3years old. The average calculous size was 16.5mm (range: 10–36mm). In 20 patients, access was achieved through the all-seeing needle method. In the other patients, access was achieved by the microsheath method. Conversion to mini-PNL was required in 2 patients due to intraoperative bleeding in one and a high stone burden in the other. The mean hospital stay was 3.8±1.2days (range: 1–10days), and the mean hemoglobin decrease was 0.7±0.3mg/dl (range: 0–1.7mg/dl).The duration of surgery and fluoroscopic screening was 75min and 3.7min, respectively. A DJ stent was placed in 11 patients due to a high stone burden. A ureteral stent was left for 1day in the rest of the cases. Complete clearance was achieved in the other 32 children. None of the patients required transfusion caused by renal hemorrhage. In 1 patient, extravasation of the irrigation fluid caused abdominal distention. As assessed by KUB and/or an ultrasound, the overall stone-free rate at 6weeks was 80%. There were residual fragments in 6 patients (15%). ConclusionsOur results show that microperc is a safe and effective procedure for the treatment of pediatric kidney stones. Children with small renal calculi and with nonobstructed collecting systems are suitable for microperc.

Ultrasound-guided micropercutaneous nephrolithotomy in pediatric patients with kidney stones.

To present the outcomes of ultrasound-guided micropercutaneous nephrolithotomy for the treatment of renal stones in pediatric patients. Ultrasound-guided micropercutaneous nephrolithotomy was carried out on 25 pediatric patients from June 2012 to October 2014. Micropercutaneous nephrolithotomy surgery was completed without the use of fluoroscopy in 19 patients. Medical records were retrieved from our institutional database and retrospectively reviewed. Percutaneous puncture was carried out by an "all-seeing needle" in seven patients and by a 14-G intravenous cannula in 18 patients. After entering to the collecting system through an "all-seeing needle" or by Microsheath, the calculus was fragmented using a 273-micron holmium yttrium aluminium garnet laser. After the stone was fragmented to the smallest pieces possible, the operation was terminated. Single access was obtained in all patients using ultrasound guidance. The average age of the patients was 4.12 ± 5.33 years. The mean stone size was 13.45 ± 3.11 mm. The mean operative time was 51.45 ± 30.69 min. The mean duration of hospitalization was 3.18 ± 1.77 days. Treatment success was 92%. Two patients had residual fragments after the procedure; these patients were followed conservatively. A total of three minor complications were observed and all of them were managed conservatively. To our knowledge, this is the first study of ultrasound-guided micropercutaneous nephrolithotomy in the pediatric population. Our findings suggest that micropercutaneous nephrolithotomy can be safely carried out with ultrasound guidance in children by experienced hands, allowing to minimize risks associated with radiation exposure in this patient population.

A Comparison of 2 Percutaneous Nephrolithotomy Techniques for the Treatment of Pediatric Kidney Stones of Sizes 10-20 mm: Microperc vs Miniperc

To compare outcomes of micro-percutaneous nephrolithotomy (PNL; microperc) with mini-PNL (miniperc) in the treatment of pediatric renal stones of sizes 10-20 mm. Patients aged <18 years who underwent PNL for renal stones of sizes 10-20 mm between August 2011 and March 2014 in 3 referral centers were reviewed retrospectively. Patients were evaluated in the following 2 groups: microperc (group 1) and miniperc (group 2). Demographics and perioperative parameters (fluoroscopy and operation time, hemoglobin drop, and stone-free and complication rates) were retrospectively analyzed. A total of 119 patients were evaluated, including group 1 (n = 56) for microperc and group 2 (n = 63) for miniperc. We found mean stone sizes as 13.4 ± 3.4 and 14.8 ± 3.7 mm in the groups, respectively (P = .046). Mean operation and fluoroscopy times were 57.1 ± 31.2 minutes and 132.4 ± 92.5 seconds in the microperc group and 68.9 ± 36.7 minutes and 226.2 ± 166.2 seconds in the miniperc group, respectively (P = .110 and P <.001). Stone-free rates were similar in both groups (82.1% vs 87.3%; P = .433 and 92.8% vs 93.6%; P = 0673) on postoperative day 1 and at first-month follow-up. The mean hemoglobin drop in group 2 differed from that in group 1 significantly (P <.001). The difference of average hospitalization times was statistically significant (43.0 ± 15.4 vs 68.5 ± 31.7 hours; P <.001). Our outcomes show that microperc may be preferred as an alternative to mini-PNL for the treatment of pediatric kidney stones of sizes 10-20 mm with comparable success and complication rates, as well as shorter hospitalization and fluoroscopy times.

Contemporary Management of Medium-Sized (10-20 mm) Renal Stones: A Retrospective Multicenter Observational Study.

To evaluate contemporary management approaches to medium-sized (10-20 mm) renal stones. A total of 935 patients treated for medium-sized renal stones (10-20 mm) between July 2012 and March 2014 were included in the study program. Contemporary minimally invasive approaches applied in the management of such stones were evaluated and compared. The cohort consisted of 561 male (60%) and 374 female (40%) patients. Of the 935 patients with medium-sized renal calculi, 535 (57.2%) were treated with shockwave lithotripsy (SWL), 201 (21.4%) with retrograde intrarenal surgery (RIRS), 110 (11.7%) with minimally invasive percutaneous nephrolithotomy (miniperc), and the remaining 89 (11.7%) patients with micropercutaneous nephrolithotomy (microperc). In the SWL group, stones were located mostly in the pelvis (51%), while in the miniperc and microperc groups, they were located mainly in the lower pole (46%, 53%, respectively). Stone-free rates after a single session were 77.2%, 86.1%, 88.8%, and 83.6% in the SWL, RIRS, microperc, and miniperc groups, respectively. Although no serious complications (above Clavien level III) were noted in any of the groups evaluated, Clavien I to II complications were common in the miniperc group. Although SWL is the preferred treatment option for patients with medium-sized (10-20 mm) renal stones, endourologic methods also have been found to have a significant role. Relatively lower complication rates along with higher stone-free status observed with the RIRS technique compared with percutaneous approaches have made this method a valuable option in the management of such stones in recent years.

A case of micro-percutaneous nephrolithotomy with macro complication.

Percutaneous nephrolithotomy is accepted as the standard management approach for kidney stones that are either refractory to extracorporeal shock wave lithotripsy or are >2 cm in diameter. The recently developed micro-percutaneous nephrolithotomy (microperc) technique provides intrarenal access under full vision using an optic instrument with a smaller calibration. A lesser amount of bleeding has been reported with the use of this method. Here we present a case of a bleeding complication on postoperative day 15 after a microperc procedure used to treat a left kidney stone. The complication led to retention of bloody urine in the bladder and required transfusion of 5 units of whole blood.

Is Micropercutaneous Nephrolithotomy Technique Really Efficacicous for the Treatment of Moderate Size Renal Calculi? Yes

Objective: To present our clinical experiences with micropercutaneous nephrolithotomy in the treatment of moderate-sized renal calculi from a single center. Methods: We retrospectively evaluated the patients with moderate-sized renal calculi who underwent micro-percutaneous nephrolithotomy between December 2012 and Septermber 2013. Results: A total of 68 patients and 70 renal units underwent microperc procedure. Mean age of patients was 41.4 ± 18.8. The mean stone size was 122 ± 83 mm². The operations were performed under spinal anesthesia in 89.7% of the patients. Stone-free rate was 95.7 % (67/70). Clinically significant residual fragments were observed in three patients. The average duration of operation and mean fluoroscopy time was 40 ± 23 min and 108 ± 72 s, respectively. The mean postoperative drop in hemoglobin was 0.95 ± 0.7 while no patient required blood transfusion. Patients were discharged after an average hospitalization time of 27.5 ± 12.4 h. A total of 4 complications (5.7%), including urinary tract infection (Clavien I) in one patient and renal colics requiring stent insertion (Clavien IIIa) in three patients, were observed postoperatively. Conclusion: Microperc technique is safe, feasible, and efficacious. We suggest that micro-percutaneous nephrolithotomy should be considered for the treatment of moderate-sized renal stones as an alternative to SWL and RIRS failures and also may be considered even primarily.

Is micro-percutaneous nephrolithotomy surgery technically feasible and efficient under spinal anesthesia?

The objective of the study was to present the clinical and operative effects of two types of anesthesia on micro-percutaneous nephrolithotomy ("microperc"). We retrospectively reviewed 116 patients who underwent microperc between August 2011 and September 2013. Patients were sorted into one of the two groups according to the type of anesthesia received: general (Group 1, n:53) or spinal (Group 2, n:63). Perioperative variables (age, stone size, location) and outcomes (operation time, success, complication rate) were evaluated and compared. Although there was a statistically significant difference in the mean age of patients (30.3 ± 22.1 vs. 45.8 ± 14.6, respectively, p < 0.001), mean body mass indexes were similar (p = 0.689). There was no substantial difference in terms of sizes and localizations of stones in the two groups (p = 0.970 and p = 0.795). While a significant difference was found in comparison of operative times (59.62 ± 32.56 vs. 40.98 ± 26.45 min, p < 0.001), there was no statistically significant difference in mean fluoroscopy times (124.92 ± 84.2 vs. 105.2 ± 61.0 s, p = 0.441). Stone-free rates were similar (90.5% vs. 93.6%, p = 0.297). We found no statistical differences between the two groups with respect to mean hemoglobin drop and hospitalization time (p = 0.015 and p = 0.917, respectively). The complication rates and analog pain scores were also similar (p = 0.543 and p = 0.365). Our results show that microperc is a feasible surgical modality in the treatment of kidney stone disease under both spinal and general anesthesia. Spinal anesthesia may be considered for patients at a high risk for general anesthesia, and also may be an alternative for patients who are concerned about and/or fearful of general anesthesia.

Does the presence of hydronephrosis have effects on micropercutaneous nephrolithotomy?

To evaluate the effects of presence of hydronephrosis on micropercutaneous nephrolithotomy (micro-PNL) surgery. A retrospective analysis of 112 patients who underwent microperc surgery between December 2012 and April 2014 was performed. Patients were evaluated in two groups according to whether the presence of hydronephrosis. Stone size and location, fluoroscopy and operation time, stone-free rates and patient-related parameters were prospectively recorded into a centralized computer-generated system. A total of 58 patients in Group 1 with hydronephrosis and 54 patients in Group 2 with no hydronephrosis were analyzed. There was no statistically significant difference in terms of stone sizes and body mass indexes (BMI) in comparison of groups (155.2 ± 93.06 vs. 143.70 ± 70.77 mm(2), p = 0.856 and 27.6 ± 4.2 vs. 26.7 ± 3.2 kg/m(2), p = 0.625). The success rates were similar (91.3 vs. 92.5%, p = 0.341). While the mean operation time and fluoroscopy time in Group 1 were 44.2 ± 23.62 min and 105.3 ± 47 s, it was 38.8 ± 26.4 min and 112.53 ± 68.3 s in Group 2, but there was no statistical difference in comparison of both groups. The mean attempts of percutan puncture were 1.35 ± 0.47 in Group 1 and 1.76 ± 0.31 in Group 2 (p = 0.185). We also found no statistical differences regarding mean hemoglobin change and hospitalization time, respectively (p = 0.685 and p = 0753). In comparison of grades of hydronephrosis, there was no statistically significant difference in subgroups analysis. The presence of hydronephrosis does not affect success rates and operative time in micro-PNL procedures significantly. Micropercutaneous nephrolithotomy is technically feasible and efficacious both in hydronephrotic and non-hydronephrotic kidneys.

A Major Complication in Micropercutaneous Nephrolithotomy: Upper Calyceal Perforation with Extrarenal Migration of Stone Fragments due to Increased Intrarenal Pelvic Pressure

Micropercutaneous nephrolithotomy is a safe and efficient technique for appropriate sized stones. It is performed through a 4.85 Fr all-seeing needle and stones are fragmented into dust, without the need for tract dilatation, unlike other percutaneous nephrolithotomy types. Even though micropercutaneous nephrolithotomy has many advantages, increase in intrapelvic pressure during surgery may cause rare but serious complications. Herein we report a case of micropercutaneous nephrolithotomy in a 20-year-old woman with a 20 mm right renal pelvis stone and present an undesired outcome of this complication, upper calyceal perforation. Right lower calyceal access was performed with 4.85 Fr all-seeing needle and 2 cm renal pelvis stone was fragmented by 272 μm Holmium-Yag laser system. Upper calyceal perforation and infrahepatic accumulation of stone fragments were detected by fluoroscopy during the surgery. Postoperative imagings revealed perirenal urinoma, perirenal and infrahepatic stone fragments, and lower calyceal stone fragments inside the system. On second postoperative day, minipercutaneous nephrolithotomy and double J catheter insertion procedures were applied for effective drainage and stone clearance. Risk of calyceal perforation and urinoma formation, due to increased intrapelvic pressure during micropercutaneous nephrolithotomy, should be kept in mind.

Treatment of symptomatic lower pole stones of a kidney with partial nephrectomy using micropercutaneous nephrolithotomy technique.

We present the treatment of lower pole stones of a 62-year-old male patient with a history of open partial nephrectomy due to renal angiomyolipoma and renal stones. He was successfully treated with micropercutaneous nephrolithotomy technique under spinal anesthesia in spite of fibrotic and scar tissue due to previous open surgery. The patient was stone-free and was discharged after a 24-hour hospitalization period. There is not any published report of micropercutaneous nephrolithotomy in a partial nephrectomized kidney before. In this report, we suggest that microperc technique may be considered for challenging conditions in case of failed retrograde intrarenal surgery.

S063: Is micro-percutaneous nephrolithotomy surgery technically feasible and efficient under spinal anesthesia?

S063: Is micro-percutaneous nephrolithotomy surgery technically feasible and efficient under spinal anesthesia?

S198: Laparoscopy assisted micro-percutaneous nephrolithotomy in a pelvic kidney

S198: Laparoscopy assisted micro-percutaneous nephrolithotomy in a pelvic kidney

Comparative study of retrograde intrarenal surgery and micropercutaneous nephrolithotomy in the treatment of intermediate-sized kidney stones

ObjectiveRetrograde intrarenal surgery (RIRS) has proven efficacy with minimal morbidity in the treatment of intermediate-sized kidney stones. The aim of this study was to examine the feasibility of micropercutaneous nephrolithotomy (microperc) for this indication and evaluate its results compared with those of RIRS. Material and methodsFrom September to December 2013, we performed a comparative prospective study between RIRS and microperc, with 20 consecutive patients with intermediate-sized (1–3cm) kidney stones. We employed a flexible dual-channel ureteroscope (Cobra, RichardWolf GmbH) and a Microperc 4.85/8 Fr (with the patient supine) with flexible fiberoptics (0.9mm, 120 and 10,000 pixels) (PolyDiagnost GmbH). The study variables were demographic data, stone characteristics, percentage of stone elimination, complications (Clavien–Dindo), surgical time, hospital stay and need for auxiliary procedures. ResultsThe patients underwent RIRS (n=12) or microperc (n=8). There were no differences in the demographics or stone characteristics between the two groups. The percentage of stone elimination with RIRS and microperc was 91.7% and 87.5% (P=1), respectively. One of the patients who underwent RIRS (8.3%) experienced postoperative fever; one of the patients who underwent microperc (12.5%) experienced postoperative colic pain (both cases were classified as Clavien I). The operative times were similar: 120min (111.2–148.7) and 120 (88.7–167.5) min for RIRS and microperc (P=.8), respectively. None of the patients required a blood transfusion. The hospital stays were also equivalent: 1 day (1–2) and 1.5 days (1–3.5) for RIRS and microperc (P=.33), respectively. Two patients treated with microperc (25%) required auxiliary procedures (simultaneous RIRS and flexible nephroscopy after percutaneous trajectory dilation to treat, in both cases, a significant fragment that had migrated to an inaccessible calyx), and 1 patient in the RIRS group (8.3%) required percutaneous nephrolithotomy due to unfavorable infundibular-calyceal anatomy (P=.54). ConclusionsMicroperc is a minimally invasive method that is emerging as an effective and safe treatment for intermediate-sized kidney stones. Studies are needed to better evaluate its cost-effectiveness, the need for complementary treatments and its possible complementarity with RIRS when working with patients in the supine position.

Estudio comparativo entre cirugía retrógrada intrarrenal y micro-nefrolitotomía percutánea en el tratamiento de la litiasis renal de tamaño intermedio

ObjectiveRetrograde intrarenal surgery (RIRS) has proven efficacy with minimal morbidity in the treatment of intermediate-sized kidney stones. The aim of this study was to examine the feasibility of micropercutaneous nephrolithotomy (microperc) for this indication and evaluate its results compared with those of RIRS. Material and methodsFrom September to December 2013, we performed a comparative prospective study between RIRS and microperc, with 20 consecutive patients with intermediate-sized (1–3cm) kidney stones. We employed a flexible dual-channel ureteroscope (Cobra, Richard Wolf GmbH) and a Microperc 4.85/8 Fr (with the patient supine) with flexible fiberoptics (0.9mm, 120° and 10,000 pixels) (PolyDiagnost GmbH). The study variables were demographic data, stone characteristics, percentage of stone elimination, complications (Clavien-Dindo), surgical time, hospital stay and need for auxiliary procedures. ResultsThe patients underwent RIRS (n=12) or microperc (n=8). There were no differences in the demographics or stone characteristics between the 2 groups. The percentage of stone elimination with RIRS and microperc was 91.7% and 87.5% (P=1), respectively. One of the patients who underwent RIRS (8.3%) experienced postoperative fever; one of the patients who underwent microperc (12.5%) experienced postoperative colic pain (both cases were classified as Clavien I). The operative times were similar: 120min (111.2–148.7) and 120 (88.7–167.5) min for RIRS and microperc (P=.8), respectively. None of the patients required a blood transfusion. The hospital stays were also equivalent: 1 day (1–2) and 1.5 days (1–3.5) for RIRS and microperc (P=.33), respectively. Two patients treated with microperc (25%) required auxiliary procedures (simultaneous RIRS and flexible nephroscopy after percutaneous trajectory dilation to treat, in both cases, a significant fragment that had migrated to an inaccessible calyx), and 1 patient in the RIRS group (8.3%) required percutaneous nephrolithotomy due to unfavorable infundibular-calyceal anatomy (P=.54). ConclusionsMicroperc is a minimally invasive method that is emerging as an effective and safe treatment for intermediate-sized kidney stones. Studies are needed to better evaluate its cost-effectiveness, the need for complementary treatments and its possible complementarity with RIRS when working with patients in the supine position.

Micropercutaneous nephrolithotomy. A new therapeutic option for pediatric renal lithiasis

IntroductionMicropercutaneous nephrolithotomy is an evolution from the conventional percutaneous surgery in which pyelocaliceal access is obtained through minimum bore holes. Its objective is the complete removal of the calculi, lowering the morbidity associated with larger bore percutaneous tracts. Materials and methodsWe present the case of a micropercutaneous nephrolithotomy performed in a 14-year-old female patient with a 35mm diameter kidney stone located in the renal pelvis. Surgery was performed in the Galdakao-modified supine Valdivia position. Puncture was done under ultrasound and fluoroscopic guidance. The 4.85Ch needle of the Microperc® set was used, completing the procedure through the 8Ch working shaft. Lasertripsy was done with the Ho:YAG laser. An indwelling double J stent was placed at the end of the procedure. ResultsOperating time was 170min. Hospital stay was one day. She suffered renal colic after 72h, which was resolved with oral analgesic treatment at home (Clavien I). She returned to school on the fifth postoperative day. The double J was removed at two weeks. At one month of the surgery, the patient is asymptomatic, a 4mm lower calyx residual stone being observed in the abdominal ultrasound. ConclusionMicropercutaneous nephrolithotomy is a step forward toward the search for a less invasive kidney stone treatment. It is a safe and effective technique in the pediatric population, and it can be performed in the supine position, even in orthotropic kidneys. Future studies and collaborative works will help to better define its indications, to optimize its technique and to analyze its cost-effectiveness compared with other treatment options.

614 The treatment of moderate size renal calculi with micro-percutaneous nephrolithotomy technique: Our clinical experiences

614 The treatment of moderate size renal calculi with micro-percutaneous nephrolithotomy technique: Our clinical experiences

Nefrolitotomía micropercutánea: una nueva opción terapéutica para la litiasis renal pediátrica

IntroductionMicropercutaneous nephrolithotomy is an evolution from the conventional percutaneous surgery in which pyelocaliceal access is obtained through minimum bore holes. Its objective is the complete removal of the calculi, lowering the morbidity associated with larger bore percutaneous tracts. Material and methodsWe present the case of a micropercutaneous nephrolithotomy performed in a 14-year-old female patient with a 35mm diameter kidney stone located in the renal pelvis. Surgery was performed in the Galdakao-modified supine Valdivia position. Puncture was done under ultrasound and fluoroscopic guidance. The 4.85Ch needle of the Microperc® set was used, completing the procedure through the 8Ch working shaft. Lasertripsy was done with the Ho:YAG laser. An indwelling double J stent was placed at the end of the procedure. ResultsOperating time was 170minutes. Hospital stay was one day. She suffered renal colic after 72hours, which was resolved with oral analgesic treatment at home (Clavien I). She returned to school on the fifth postoperative day. The double J was removed at 2 weeks. At one month of the surgery, the patient is asymptomatic, a 4mm lower calyx residual stone being observed in the abdominal ultrasound. ConclusionMicropercutaneous nephrolithotomy is a step forward towards the search for a less invasive kidney stone treatment. It is a safe and effective technique in the pediatric population, and it can be performed in the supine position, even in orthotropic kidneys. Future studies and collaborative works will help to better define its indications, to optimize its technique and to analyze its cost-effectiveness compared with other treatment options.

Comparison of intrarenal pelvic pressure during micro-percutaneous nephrolithotomy and conventional percutaneous nephrolithotomy

The micro-percutaneous nephrolithotomy (microperc) is a recently introduced percutaneous nephrolithotomy (PNL) technique that is performed through a 4.8 Fr all-seeing needle. We aimed to measure the intrarenal pelvic pressure (IPP) during microperc and compare it with the levels of conventional PNL. A total of 20 patients with 1- to 3-cm renal calculi resistant to shock wave lithotripsy were treated either with microperc (Group-1, n: 10) or conventional PNL (Group-2, n: 10) by the same surgical team. The IPP was measured during different stages (entrance into the collecting system, stone fragmentation, and before termination) of the procedures by an urodynamic machine using the 6 Fr ureteral catheter. All the variables were statistically compared between the two groups. The demographic values of the patients were similar. The operation time and duration of hospitalization were significantly prolonged in conventional PNL group (p = 0.034, p = 0.01, respectively). The mean drop in hematocrit levels was significantly lower in microperc group (3.5 ± 1.5 vs. 1.8 ± 0.8; p = 0.004). The IPP was significantly higher in microperc group during all steps of the procedure. The highest level of the IPP was measured as 30.3 ± 3.9 and 20.1 ± 3.1 mmHg in Group 1 and Group 2, respectively (p < 0.0001). However, the complication and success rates were found comparable. In conclusion, we demonstrate that the level of IPP is significantly increased during microperc compared to conventional PNL. Microperc should be used cautiously in cases with impaired drainage of the collecting system.

Initial experience of micro-percutaneous nephrolithotomy in the treatment of renal calculi in 140 renal units

The aim of this study was to investigate the effectiveness and reliability of the micro-percutaneous nephrolithotomy (PNL) method for the management of kidney stones. We performed a retrospective analysis of 136 patients (140 renal units) who underwent micro-PNL for renal stones between September 2011 and February 2013 in four referral hospitals in Turkey. The selection of treatment modality was primarily based on factors such as stone size and location. In this study, we analyzed patient- and procedure-related factors. The mean age of patients in this study was 28.7 ± 20.6 (1-69) years, and the mean stone size was 15.1 ± 5.15 (6-32) mm. Conversion to mini-PNL was required in 12 patients. All interventions were performed with the patient in the prone position, except for the 3-year-old patient with the pelvic kidney who was placed in the supine position. The mean hospital stay was 1.76 ± 0.65 (1-4) days, and the mean drop in the hemoglobin level was 0.87 ± 0.84 (0-4.1) mg/dL. One of our patients required transfusion. Ureteral J stent was implanted in nine (6.43 %) patients because of residual stones. Seven (6.43 %) patients complained of postoperative renal colic which was managed conservatively. Abdominal distension related to extravasation of the irrigation fluid was observed in three patients (2.19 %). There were no other postoperative complications. An overall success rate of 82.14 % was achieved. Micro-PNL can be effectively and safely used for small and moderate kidney stones resistant to shock wave lithotripsy or as an alternative to other minimally invasive treatment methods.