Percutaneous nephrolithotomy in the supine position: technical aspects and functional outcome compared with the prone technique

Comparison of safety and efficacy of different positions in percutaneous nephrolithotomy: a network meta-analysis

OBJECTIVES

Various new positions for percutaneous nephrolithotomy (PCNL) were proposed to reduce the limitations of the traditional position. This study was aimed to evaluate the efficacy and safety of the different PCNL positions.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for relevant randomized controlled trials (RCTs) up to 18 April 2023. The authors collected five common surgical positions used for PCNL: oblique supine position (OSP), supine position (SP), flank position (FP), split-leg oblique supine/flank position (SLP), and prone position (PP). Paired and network meta-analysis were conducted to compare relevant outcomes, including complications, operative time, stone-free rates, hospital stay, and hemoglobin loss among these different positions.

RESULTS

The study included 17 RCTs with a total of 1841 patients. The result demonstrated that SLP significantly outperformed in terms of decreasing operation time (FP vs SLP MD- MD-41.65; OSP vs SLP MD 28.97; PP vs SLP MD 34.94), hospital stay, and hemoglobin loss. Ranking probabilities showed SLP had highest stone-free rate. Prone position was more likely to occur complications than others. Based on SMAA model, the benefit-risk analysis suggested the SLP was the optimal position in PCNL.

CONCLUSIONS

For PCNL, the split-leg, flank, supine, and OSPs are as secure as the prone position. Further RCTs are necessary to confirm the outstanding safety and efficacy of split-leg position. Besides, the position should be selected regard for the patient's demands, the surgeon's preference and learning curve.

Could pain change position choice? Comparison of pain level, analgesic requirement and hospitalization time in supine and prone percutaneous nephrolithotomy

PURPOSE

Investigation of how position affects postoperative pain levels and hospitalization in patients undergoing percutaneous nephrolithotomy (PNL) surgery.

METHODS

Between August 2019 and December 2022, a total of 156 patients who underwent prone (pPNL) and supine percutaneous nephrolithotomy (sPNL) due to kidney stones were included in the study. Demographic data, preoperative CT scans, laboratory results, transfusion rates, operation durations, complication rates, stone-free rates, analgesic use, nephrostomy removal time, hospitalization duration, fluoroscopy time, hemoglobin decrease and postoperative Visual Analog Scale (VAS) scores were evaluated for all patients. By comparing these data between the sPNL and pPNL groups, the effect of position selection in PNL on pain control, analgesic requirement, and hospitalization duration was examined.

RESULTS

In the comparison of the pPNL and sPNL groups, there was a significant difference between the two groups in body mass index, hounsfield unit, complication rate, analgesic rate, nephrostomy remove time, hospitalization time, operation time, fluoroscopy time and VAS score (p = 0.025, p < 0.001, p = 0.012, p = 0.012, p < 0.001, p < 0.001, p < 0.001, p < 0.001 and p < 0.001, respectively).

CONCLUSION

The shorter operation and hospitalization time in the sPNL group could be attributed to performing surgeries in a physiological position. Additionally, sPNL seems advantageous in terms of patients' pain levels, hospitalization time and VAS scores. One reason for this could be the different areas of access in sPNL and pPNL, which may correspond to different dermatome regions. Considering the low level of pain and reduced analgesic usage, sPNL appears to be advantageous.

Calcutta position: A new modified supine decubitus for supine PCNL

INTRODUCTION

PCNL (percutaneous nephrolithotripsy) is considered the gold standard treatment for renal stone more than 2 cm. In today's scenario, supine PCNL is considered equally effective as prone PCNL. The ideal position for supine PCNL is still debatable. We hereby describe our initial experiences of supine PCNL in a novel position.

METHODS AND MATERIALS

This prospective study includes 60 patients who underwent supine PCNL in the 'Calcutta position' in our institute from August 2021 to August 2022. Successful procedure was defined as a complete stone free rate or a clinically insignificant residual stone (<4 mm).

RESULTS

Average Operative room (OR) occupancy time was 130.9 ± 19.63 min. The immediate stone free rate was 84.2%, 71.4% and 37.5% for single, multiple and staghorn calculus respectively. Complications include fever, requirement of blood transfusions and renal colic. The average hospital stay was 83.6 ± 17.42 h. Eight patients (13.3%) required secondary procedures like extracorporeal shock wave lithotripsy (ESWL) or relook PCNL. At 3 months average stone free rates were 92%, 85%, 75% for single, multiple and staghorn calculus respectively. We performed supine PCNL in Calcutta position in obese, kyphoscoliosis, poliomyelitis, autosomal polycystic kidney disease (ADPKD), malrotated kidney and diverticular stone with comparable success.

CONCLUSION

Supine PCNL in Calcutta position is a safe and effective option for nephrolithiasis management. Apart from the inherent advantages of supine PCNL it also has the advantages of better C-Arm and nephroscope manoeuvrability. Supine PCNL in Calcutta position was performed in a variety of scenarios with comparable results.

Comparative Study of Prone Position Variations for Percutaneous Nephrolithotomy

Objective

In this comparative study, we evaluated the results of flat prone and prone hip flexed percutaneous nephrolithotomy in terms of efficacy and safety to contribute to the optimal prone percutaneous nephrolithotomy position.

Materials and Methods

Data of the patients who underwent percutaneous nephrolithotomy operations in a flat-prone or prone hip flexed positions due to renal pelvis and/or ≥2 Calix filling stones between January 2016 and January 2022 were collected retrospectively. Demographic data of the patient groups in different prone positions as well as clinical findings, stone characteristics and operative data were analyzed. The groups were also compared in terms of post-operative findings and complications.

Results

The average age and CROES scores of patients included in the study were 47.15±15.6 years and 221.76±62.49, respectively. There was no statistically significant difference between the two groups in terms of patient demographic data, stone-free status and complication rates. Operation Room Time (ORT) (min) in flat prone PCNL group was shorter in average (100.57±32.74 min vs 92.32±28.75 min, p = 0.041) and duration with nephrostomy (days) and hospitalization (days) parameters were statistically significantly shorter in prone hip flexed PCNL (respectively, p < 0.001; p = 0.005).

Conclusion

Flat-prone PCNL provides significantly shorter ORT. However, the time with nephrostomy and hospitalization with the prone hip flexed PCNL were shorter than flat-prone position. The findings will guide the optimal prone PCNL position.

Supine PCNL-5 year experience in a tertiary care center

OBJECTIVE

The prone position for percutaneous nephrolithomy (PCNL) has been widely practiced. There has been a shift from prone position to supine position which showed numerous benefits. The aim of our study is to describe the 5 year experience from the perspective of a tertiary care center using a modified Galdakao supine Valdivia position for total tubeless ultra mini supine PCNL, total tubeless supine PCNL, tubeless supine PCNL, and standard supine PCNL.

MATERIAL AND METHODS

We retrospectively reviewed the data of 90 patients who underwent supine PCNL at the tertiary care center during the period of 5 years from January 2017 to January 2021. The data collection was done from patients' medical records. Pre operatively, complete examination of the patients with laboratory investigations were done. The modified Clavien classification system was used to classify the perioperative complications of PCNL.

RESULTS

Operative time was lowest for ultra mini supine PCNL (50 ± 10.4 min) compared to standard supine PCNL (58 ± 11.2 min). Stones were single in 54 patients and multiple in 40 patients with 4 patients with staghorn stones. The size of the stones in the largest dimension ranged from 1.2 to 5.5 cm.Complete clearance was achieved in 84 (89.7%) patients. Seven patients (7.2%) developed mild fever and four patients (4.5%) required blood transfusion.

CONCLUSION

We found supine PCNL to be an immensely convenient, time-saving practice, and with higher stone free rate compared to prone PCNL. The different techniques of supine PCNL were also useful in patients with horseshoe kidney and calyceal diverticulum which resulted in good outcomes in these patients.

Comparative study between a new screwed Amplatz sheath and the ordinary one in percutaneous nephrolithotomy

Objective

The objective of the article is to compare the results of using new screwed Amplatz sheath with results of the conventional Amplatz sheath regarding success and complications during percutaneous nephrolithotomy.

Methods

100 patients aged more than 18 years with renal calculi more than 2 cm with guy's score 1 from December 2018 till July 2020 were randomly stratified by closed envelope in group A (50 patients) with using conventional sheath and group B (50 patients) with new screwed sheath. We exclude morbid obese patients and patients with contraindication for PNL.

Results

There were no significant differences between both groups regarding patients demographic and stone demographic. Operative time and fluoroscopy time were significantly lower in group B rather than group A. Tract stability was in favor of group B as no tract loss recorded while in group A, 5 cases were recorded. In overall complications there were no significant differences between both groups. Bleeding was higher in group A (14%) than in group B (4%), but it was not statistically significant. Success rates were 78% for group A and 88% for group B but it was not statistically significant.

Conclusion

The screwed Amplatz sheath had showed less operative and fluoroscopy time. Also it enables urologists to have stable PNL tract. So it may be a promising tool to make PNL easier with higher success rate and lower complications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-021-03806-2.

A study on comparative outcomes of totally ultrasonography-guided percutaneous nephrolithotomy in prone versus flank position: a randomized clinical trial

PURPOSE

The percutaneous nephrolithotomy (PCNL) has become the gold-standard for treating patients with the larger renal stones and staghorn calculi. This study was designed to evaluate the outcomes of flank versus prone position in patients underwent ultrasonic-guided PCNL for treatment of large kidney stones.

METHODS

This prospective randomized clinical trial was conducted from September 2017 to September 2019 in the department of Urology, Labbafinejad University hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Two hundred patients with kidney stones larger than 2 cm underwent PCNLs in prone (n = 100) or flank position (n = 100). Success rate, operative time, access time, hemoglobin and creatinine changes, hospital stay, auxiliary procedure and surgical complications were compared between the two groups.

RESULTS

The two groups were similar in their baseline characteristics. The success rates in prone (87%) versus flank position (85%) were not significantly different at the first post-operative follow-up (p = 0.91). At the three-month follow-up, the overall stone free rates for the prone position PCNLs and flank position PCNLs were 94/100 (94%) and 90/100 (90%) (p = 0.96). There were no significant difference between the groups in operative time (p = 0.42), access time (p = 0.66), hemoglobin (p = 0.46) and creatinine (p = 0.22) changes, hospital stay (p = 0.05), auxiliary procedures (p = 0.75) and surgical complications.

CONCLUSION

Overall, there is no significant difference between prone and flank positions in success rate and complications. More prospective studies must be carried out to identify patient populations who are most apt to benefit from one position over the other.

TRIAL REGISTRATION NUMBER

IRCT20200902048597N1 DATE OF REGISTRATION: 2020-11-21, retrospectively registered.

Efficacy and safety of modified tract dilation technique using simultaneous pulling of proximal and distal ends of a guidewire for percutaneous nephrolithotomy in modified supine position

Purpose

Recently, the needs for supine percutaneous nephrolithotomy (PCNL) have become more increased because of an easy approach for endoscopic combined intrarenal surgery. However, making a nephrostomy tract during supine PCNL is more difficult than prone position due to movable kidney. To overcome this limitation, we used a modified nephrostomy tract dilation (MTD) technique using guidewire traction.

Materials and Methods

From January 2014 to June 2019, a total of 259 patients underwent PCNL in the modified supine position. Among them, the MTD technique was performed in 171 patients. For the MTD technique, two hydrophilic guidewires were passed from the nephrostomy tract and brought out through the urethra, then both proximal and distal ends were contralaterally pulled with tension for the easy placement of a fascia-cutting needle and a balloon catheter. We analyzed the efficacy of this technique in comparison with the conventional method.

Results

Intraoperative radiation exposure time (RET) (68.87 vs. 212.11 s) and hospital stay (5.90 vs. 6.74 days) were significantly shorter, while the success rate (77.2% vs. 63.6%) was significantly higher in the MTD group. Multivariate analysis showed that only the maximal stone diameter (odds ratio [OR], 1.928; 95% confidence interval [CI], 1.314–2.828; p=0.001) and MTD technique (OR, 0.017; 95% CI, 0.007–0.040; p<0.001) were independent factors for predicting short RET (<120 s).

Conclusions

This study demonstrated that MTD technique can be effectively and safely performed in modified supine position PCNL, and it can be helpful in reducing RET and enhancing success rates.

Impact of weight on stone-free rate during percutaneous nephrolithotomy

Background

To assess Impact of weight on stone-free rate during percutaneous nephrolithotomy.

Methods

Hundred and twenty-three PNL procedures were done between January 2016 and July 2017. The patients were divided into four groups according to the World Health Organization (WHO) classification of body mass index (BMI): < 25 ((group 1, average)), 25–29.9 (group 2, overweight), 30–39.9 (group 3, obese), and ≥ 40 kg/m2 (group 4, morbidly obese). All groups were compared as regarding preoperative variables, intra-operative procedure and postoperative results.

Results

The non-obese groups were younger in age than obese and morbid obese groups (P = 0.005). The difference in BMI was statistically significant between non-obese and obese groups (P = 0.0001). Most of females gender were obese and morbid obese (P = 0.0001) and most of the obese patients had left-sided renal stone (P = 0.001). Most of overweight and obese groups had radiopaque stones (P = 0.02). There were no statistically significant differences between all groups as regarding co-morbidity, stone size, stone locations, and hydronephrosis grade. Operative time (P = 0.034), length of hospital stay (P value = 0.014) and fluoroscopy time (P = 0.0001) were statistically significant differences between all groups. Number of accesses, access site, postoperative hemoglobin drop, post- operative complications, fate of residual stones and stone-free rate were not statistically significant differences between all groups. BMI was correlated with mean fluoroscopy time and mean hospitalization duration in our study as the time of hospitalization and time of x-ray exposure increase with obesity.

Conclusion

PNL is a safe and effective procedure for obese patients. BMI do not predict clearance post PNL.

Supine versus prone position for percutaneous nephrolithotripsy: A meta-analysis of randomized controlled trials

OBJECTIVE

To compare the safety and efficacy of percutaneous nephrolithotripsy (PCNL) in supine versus prone position for patients with renal or upper ureteral calculi.

METHODS

A systematic search of Pubmed, Embase and Cochrane Central Register of Controlled Trials was performed to identify all eligible studies. All included randomized controlled trials (RCTs) were evaluated based on the inclusion and exclusion criteria. After quality assessment and date extraction, a meta-analysis was performed using RevMan 5.3 software.

RESULTS

A total of 15 RCTs with 1474 patients were included in our meta-analysis. Pooled data showed that PCNL in supine position could significantly reduce the operative time [weighted mean difference (WMD) -12.02, 95% confidence interval (CI) -20.49 to -3.54, p = 0.005] and rate of fever [risk ratio (RR) 0.67, 95% CI 0.46 to 0.97, p = 0.03] compared to prone position. In addition, no significant differences could be found between groups in stone-free rate (p = 0.31), hospital stay (p = 0.59) and rate of overall complications (p = 0.11), mainly including urinary leakage (p = 0.83), pleural effusion (p = 0.74) and blood transfusion (p = 0.58).

CONCLUSIONS

The current study found comparable stone-free rate and significant lower rate of postoperative fever in supine PCNL compared with prone PCNL. PCNL in supine position could be a safe and efficient choice for patients with renal or upper ureteral calculi.

Patient positioning during percutaneous nephrolithotomy: what is the current best practice?

Percutaneous nephrolithotomy (PCNL) is the gold standard procedure for treatment of large stones and complex kidney disorders, but its morbidity remains the highest among stone treatment procedures. In pursuit of minimizing complication rates, surgeons have developed different variations of the classic prone position in which PCNL is usually performed; one among them is supine position. In this study, we review the literature and present all available evidence on different variations in positioning during PCNL, in an effort to identify if there is a position that can minimize the morbidity of this procedure.

Prospective evaluation of kidney displacement during supine mini-percutaneous nephrolithotomy: Incidence, significance, and analysis of predictive factors

INTRODUCTION

Kidney displacement may alter the quality of renal puncture during percutaneous nephrolithotomy (PCNL). The aim of this study was to identify the rate of kidney displacement and parameters associated with kidney displacement in patients who underwent supine mini-PCNL.

METHODS

Data of 98 consecutive patients who underwent mini-PCNL was collected prospectively. The patients were grouped as displacement-positive vs. -negative. The parameters collected were age, gender, body mass index, side of the kidney, punctured calyx, fluoroscopy time to successful puncture and tract dilation, stone-free and complication rates, stone diameter, length of the renal artery, and quantity of peri-renal and abdominal fat. Groups were compared for the above listed parameters and logistic regression analysis was performed to identify factors associated with kidney displacement.

RESULTS

There were 34 and 64 patients in the displacement-positive and -negative groups, respectively. Groups were similar for stone-free and complication rates. Fluoroscopy time to puncture and tract dilation were longer in the displacement-positive group. Groups were different for renal artery length and peri-renal fat measurements. In multivariate analysis, lower pole puncture, renal artery length, and peri-renal fat measurement were found to be independent predictors of kidney displacement.

CONCLUSIONS

Kidney displacement does not alter the success and complication rates, but is associated with longer fluoroscopy times during supine PCNL. In the current study, parameters in preoperative non-contrast computerized tomography (NCCT) associated with kidney displacement were identified. We recommend surgeons evaluate and take into account these parameters during preoperative planning to establish better outcomes and diminish fluoroscopy times.

Complete supine PCNL: ultrasound vs. fluoroscopic guided: a randomized clinical trial

Introduction and Hypothesis:

To compare complications and outcomes of complete supine percutaneous nephrolithotomy (csPCNL) with ultrasound guided and fluoroscopically guided procedure.

Materials and Methods:

In this randomized clinical trial study from January 2009 to September 2010, 26 of 51 patients with renal stones underwent csPCNL with ultrasonographic guidance in all steps of the procedure (group A), and the other 25 patients underwent standard fluoroscopically guided csPCNL (group B). All of the patients underwent PCNL in the complete supine position. Statistical analysis was performed with SPSS16 software.

Results:

Mean BMI was 28.14 in group A and 26.31 in group B (p=0.30). The mean stone burden was 26.48 and 30.44 in groups A and B, respectively (p=0.20). The stone free rate was 88.5% in group A and 75.5% in group B, that was no significant (p=0.16). Overall 2 patients (7.7%) in group A and 6 patients (24%) in group B had complications (p=0.11). Mean operative time in group A was 88.46 minutes, and in group B it was 79.58 minutes (p=0.39). Mean hospital stay was 69.70 and 61.79 hours in group A and B, respectively (p=0.22). There was no visceral injury in groups.

Conclusions:

This randomized study showed that totally ultrasonic had the same outcomes of fluoroscopically csPCNL. Ultrasonography can be an alternative rather than fluoroscopy in PCNL. We believe that more randomized studies are needed to allow endourologists to use sonography rather than fluoroscopy in order to avoid exposition to radiation.

Prone Versus Supine Percutaneous Nephrolithotomy: What Is Your Position?

PURPOSE OF REVIEW

Percutaneous nephrolithotomy (PCNL) is the gold standard surgical procedure for treating large, complex renal stones. Due to its challenging nature, PCNL has undergone many modifications in surgical technique, instruments, and also in patient positioning. Since the first inception of PCNL, prone position has been traditionally used. However, alternative positions have been proposed and assessed over the years. This is a comprehensive review on the latest developments related to positioning in the practice of PCNL.

RECENT FINDINGS

The prone position and its modifications are the most widely used positions for PCNL, but with the introduction of various supine positions, the optimal position has been up for debate. Recent meta-analysis has shown a superior stone-free rate in the prone position and comparable complication rates to the supine position. The advantage of ease of access to the urethra for simultaneous retrograde techniques in the supine position is also possible with modifications in the prone position such as the split-leg technique. Modern-day PCNL has transformed from an operation traditionally undertaken in the prone position to a procedure in which a prone or supine position may be employed; however, published data have not shown significant superiority of either approach.

Percutaneous nephrolithotomy: technique

Percutaneous nephrolithotomy (PCNL) is considered to be the first line of treatment for large renal stones. Though PCNL comes with higher morbidity, its efficacy is unbeaten by other minimally invasive modalities. However, potential complications, such as bleeding, occur. Improved skills and modifications of the procedure may reduce the probability of adverse outcomes. This article discusses the current trends and standards in PCNL technique with special focus on all important steps as positioning, access, instruments, dilation, disintegration, and exit, including outcomes, complication management, and training modalities.

Percutaneous nephrolithotomy in complete supine flank-free position in comparison to prone position: A single-centre experience

OBJECTIVES

To assess the outcomes of performing percutaneous nephrolithotomy (PCNL) in a modified supine position, more feasible for surgeons, anaesthetists, and operating theatre staff, as well as for the patient himself, and evaluating it in comparison to the standard prone position.

PATIENT AND METHODS

A retrospective, case-control study was conducted between January 2011 and December 2015. In all, 197 patient's records were reviewed. The initial 101 patients were operated upon in prone position. From mid-2013, 96 patients were operated upon in a complete supine, flank-free position. The groups were compared in terms of operation time, calculated from positioning the patient after anaesthesia induction, insertion of ureteric catheter, puncture of renal system, until the end of procedure; stone-free rate; hospital stay; and postoperative complications, such as transfusion rate, fever, and urinary leakage.

RESULTS

There were two significant differences between the groups. Firstly, the operation time was a mean (SD) 32.3 (6.6) min shorter for the supine versus the prone position (P < 0.001). Secondly, hospital stay was a mean (SD) 1.2 (0.75) days shorter for the supine vs the prone position (P < 0.001). The complete stone clearance rate (85.4% for supine vs 79.2% for prone; P = 0.2) and postoperative complications (7.3% for supine vs 17.8% for prone; P = 0.02) were comparable in both groups.

CONCLUSION

Supine PCNL is a feasible procedure with similar outcomes in terms of stone-free rate as well as postoperative complications, to the standard prone PCNL. It reduces unnecessary delay that occurs during change of position resulting in significant shortening of the total operation time and surgeons can perform supine PCNL whilst sitting.

Positioning for percutaneous nephrolithotomy

PURPOSE OF THE REVIEW

To highlight the progressive evolution of the issue of patient positioning for percutaneous nephrolithotomy (PNL), explain the history of the prone and supine positions, report respective advantages and drawbacks, critically interpret the past and current literature supporting such arguments, identify the best candidates for each position, and reflect on the future evolution of the two approaches.

RECENT FINDINGS

Positioning for PNL has become a matter of debate during the last decade. The traditional prone PNL position - most widely performed with good success and few complications, and exhibiting essentially no limits except for the treatment of pelvic kidneys - is nowadays flanked mainly by the supine and supine-modified positions, equally effective and probably safer from an anesthesiological point of view. Of course, both approaches have a number of advantages and drawbacks, accurately reported and critically sieved.

SUMMARY

The current challenge for endourologists is to be able to perform PNL in both prone and supine positions to perfectly tailor the procedure on any patient with any stone burden, including increasingly challenging cases and medically high-risk patients, according to the patient's best interest. Intensive training and experience is especially needed for supine PNL, still less popular and underperformed worldwide.

VIDEO ABSTRACT

http://links.lww.com/COU/A8.

What is better in percutaneous nephrolithotomy - Prone or supine? A systematic review

OBJECTIVE

To review the literature reporting the technique of percutaneous nephrolithotomy (PCNL) and outcomes for prone and supine PCNL, as PCNL is an established treatment for renal calculi and both prone and supine PCNL have been described, but there has been much debate as to the optimal position for renal access in PCNL.

METHODS

A review of the medical literature was conducted using the PubMed database to identify relevant studies reporting on prone and supine PCNL published up until July 2015. Only publications in English were considered. Search terms included 'supine', 'prone', 'percutaneous nephrolithotomy', 'PCNL' and 'randomised controlled trial'. Articles relevant to the particular aspect of PCNL discussed were selected.

RESULTS

In all, 30 articles were included in the literature review. Nine of these articles were of Level 1 Evidence as graded by the Oxford System of Evidence-based Medicine.

CONCLUSION

The present systematic review highlights the benefits and disadvantages of supine and prone PCNL. The published data on supine and prone PCNL have shown no significant superiority of either approach. Whether prone or supine PCNL is optimal, remains a debatable topic.

Percutaneous Nephrolithotomy in Patients With BMI >50: Single Surgeon Outcomes and Feasibility

OBJECTIVE

To evaluate the use of percutaneous nephrolithotomy (PNL) and technical approach in the super obese population (body mass index [BMI] ≥ 50).

MATERIALS AND METHODS

We performed a retrospective review of 31 consecutive PNL cases with a BMI > 50 from a single surgeon (SYN) from 1995 to 2013. Procedures were performed in the prone position, and upper pole access was used. Operative time, length of hospital stay, stone burden, complication rates, and stone-free rates were measured.

RESULTS

Of the 31 patients who underwent PNL (age 51.2 ± 12; 71% female), the mean BMI was 59.1 ± 6 kg/m(2) (range 50.4-71.7 kg/m(2)). Mean stone burden was 3.8 cm ± 2. The majority of patients (90.3%) had an upper pole puncture site for access with an operative time of 122.1 ± 75 minutes. The technique was similar to non-obese patients; however, there was a need for extra-long instrumentation. The overall stone-free rate was 71%, with utilization of a second-look PNL in 11 cases. The complication rate, Clavien grade 3 or higher, was 9.7% (3 of 31).

CONCLUSION

PNL is technically feasible, safe, and effective in patients with a BMI ≥ 50. The complication rate, length of hospital stay, and stone-free rate with use of second-look PNL in super obese patients are comparable to severely obese patients. Intervention should not be automatically ruled out or delayed based on the patient's BMI alone.

Does Peak Inspiratory Pressure Increase in the Prone Position? An Analysis Related to Body Mass Index

PURPOSE

Percutaneous nephrolithotomy is commonly performed with the patient prone. There is concern that the prone position, especially in obese patients, negatively affects ventilation due to the restriction of chest compliance and respiratory mechanics. We analyzed the change in airway resistance between supine and prone positioning of patients undergoing percutaneous nephrolithotomy.

MATERIALS AND METHODS

We retrospectively reviewed the intraoperative respiratory parameters of 101 patients who underwent prone percutaneous nephrolithotomy. Peak inspiratory pressure was assessed with the patient supine, at several time points after being turned prone and at the end of the case. The change in peak inspiratory pressure with time was calculated. Results were stratified based on body mass index and data were compared using the paired t-test and Spearman ρ.

RESULTS

Of 101 patients 50 (50%) were obese (body mass index 30 kg/m(2) or greater). Median body mass index was 25.6 kg/m(2) in the nonobese cohort and 38.3 kg/m(2) in the obese cohort. Average peak inspiratory pressure while supine and prone was 18.0 and 18.5 cm H2O in the nonobese cohort, and 25.5 and 26.6 cm H2O, respectively, in the obese cohort. Obese patients had significantly higher peak inspiratory pressure in the supine and the prone positions relative to nonobese patients (p <0.0001). However, there was no change in peak inspiratory pressure from the supine to the prone position in either cohort.

CONCLUSIONS

Obese patients have higher baseline peak inspiratory pressure regardless of position. However, prone positioning does not impact peak inspiratory pressure in either cohort. It remains a safe and viable option.

Supine or prone position for mini-PNL procedure: does it matter

In this study it is aimed to compare the success and complication rates of mini-PNL procedure in supine and prone positions. In this retrospective study data of 180 patients treated with MPNL either in supine (n = 54) or prone (n = 126) positions between May 2009 and August 2014 was investigated. Success was defined as no visible stones >2 mm. Perioperative complications were classified using the modified Clavien system. Groups were compared with Chi square test or Student t test and for statistical significance p value of 0.05 was accepted. Mean age of the population was 42.5 ± 8.2 years and mean stone size was 23.9 ± 4.1 mm. The two groups were similar with regard to demographic characteristics and stone related characteristics except the ASA status. Success rates of the supine and prone groups were 85.1 and 87.3%, respectively (p = 0.701). No statistically significant differences in terms of complications were observed. Mean operative time was the only parameter different between the two groups (55 vs 82 min, p = 0.001). Supine position for PNL seems to be promising and the complication and success rates are shown to be similar to the prone position with MPNL technique. The only significant benefit of this technique is shorter operative time.

How well tolerated is supine percutaneous nephrolithotomy?

PURPOSE OF REVIEW

Supine percutaneous nephrolithotomy (PCNL) has been described in 1988 and several modifications followed since. Despite claimed benefits, supine PCNL is still neglected by the majority of urologists. Lack of experience and the fear of complications are possible explanations for the resistance to supine positioning. This review evaluates recent literature on the use of supine PCNL, focussing on benefits and safety.

RECENT FINDING

The Clinical Research Office of the Endourological Society Global Study and several (retrospective) reports comment on efficacy and safety of PCNL, differences in techniques, or identify conditions and patient factors for best practice. Anesthesiologic benefits (especially in the high risk, cardiopulmonary compromised, patient) and anatomical advantages are described in supine position theoretically favoring safety of supine PCNL. However, there are no prospective randomized studies conducted to support this assumption. Overall, benefits in efficacy or safety, of one position over the other, are not yet proven.

SUMMARY

Supine PCNL has advantages in selected patients. Ultimately, the decision on position should be made on patient's characteristics and surgeon's preference and experience.

Feasibility and efficacy of intermediate-supine percutaneous nephrolithotomy: initial experience

We evaluated the feasibility and efficacy of intermediate-supine percutaneous nephrolithotomy (PCNL) in patients with renal calculi. Fifteen patients were included in this study. The intermediate-supine operative position was modified by using a 1-L saline bag below the ipsilateral upper flank. A nephrostomy and stone extraction were performed as usual. After completion of the stone removal, a nephrostomy tube was used when necessary according to the surgeon's decision. If there was no significant bleeding or renal pelvic injury, tubeless PCNL was performed. The mean stone size was 5.48±5.69 cm(2), the mean operative time was 78.93±38.72 minutes, and the mean hospital stay was 2.60±1.29 days. Tubeless PCNL was performed in 13 cases (86.7%), and retrograde procedures were simultaneously performed without a change of position in 2 patients (ureteroscopic ureterolithotomy in one patient and transurethral placement of an occlusion catheter in one patient). There were two complications according to the Clavien-Dindo classification (Grade I in one patient and Grade II in one patient). The success rate was 80.0% and the complete stone-free rate was 73.3%. Three patients with a significant remnant stone were also successfully managed with additional procedures (one patient underwent a second-look operation, and the remaining two patients were treated with shock wave lithotripsy). In the treatment of renal calculi, intermediate-supine PCNL may be a safe and effective choice that offers several advantages with excellent outcomes. Thus, a prospective study with a larger population is needed to verify our outcomes.

The clinical research office of the endourological society percutaneous nephrolithotomy global study: Outcomes in the morbidly obese patient - a case control analysis

BACKGROUND

Efficacy and safety of percutaneous nephrolithotomy (PCNL) have been demonstrated in obese individuals. Yet, there is a paucity of data on the outcomes of PCNL in morbidly obese patients (body mass index [BMI] >40).

METHODS

Perioperative and stone-related outcomes following PCNL in morbidly obese patients was assessed using a prospective database administered by the Clinical Research Office of the Endourological Society (CROES). A multidimensional match of 97 morbidly obese patients with those of normal weight was created using propensity score matching. Student's t-test and Chi-square tests were used to assess for differences between the groups.

RESULTS

In total, 97 patients with a BMI >40 kg/m(2) were matched by stone characteristics with 97 patients of normal weight. The morbidly obese population demonstrated higher rates of diabetes mellitus (43% vs. 6%, p < 0.001) and cardiovascular disease (56% vs. 18%, (p < 0.001). Access was achieved more frequently by radiologists in the morbidly obese group (19% vs. 6%, p = 0.016). Mean operative duration was longer in the morbidly obese group (112 ± 56 min vs. 86 ± 43.5 min, p < 0.001). Stone-free rates were lower in the morbidly obese group (66% vs. 77%, p = 0.071). There was no significant difference in length of hospital stay or transfusion rate. Morbidly obese patients were significantly more likely to experience a postoperative complication (22% vs. 6%, p = 0.004).

INTERPRETATION

PCNL in morbidly obese patients is associated with longer operative duration, higher rates of re-intervention and an increased risk of perioperative complications. With this knowledge, urologists should seek to develop strategies to optimize the perioperative management of such patients.

Percutaneous nephrolithotomy in the oblique supine lithotomy position and prone position: a comparative study

OBJECTIVES

To compare the safety, efficacy, and complications of percutaneous nephrolithotomy (PCNL) in the oblique supine lithotomy position vs the prone position in a randomized comparative study.

PATIENTS AND METHODS

The study included 101 and 102 patients in the oblique supine lithotomy position and prone position, respectively. Inclusion criteria were renal and upper ureteral stones. Exclusion criteria were uncorrectable bleeding disorders, active urinary tract infection, and pregnancy.

RESULTS

Both the groups were comparable regarding the male/female ratio, stone size, and site. No significant differences were found in terms of the stone-free rate, blood transfusion rate, and complication rates. Significant differences were reported in mean hemoglobin loss (-1.03 and -2.18 g/dL), mean operative time (86.16 and 111.7 minutes), and mean hospital stay (49.88 and 81.2 hours) in the supine and prone positions, respectively, and anesthesiological parameters (the mean blood pressure decreased by 2 and 14.06 mm Hg, the mean heart rate changed by -0.82 and +13.28 beat/minute, and the peak air way pressure changed by +1.08 cm H2O and +7.56 cm H2O in the supine and prone positions, respectively).

CONCLUSIONS

PCNL in both positions was equally successful with no significant differences in complications. PCNL in the oblique supine lithotomy position was superior to PCNL in the prone position regarding operative time, hospital stay, and effects on respiratory and cardiovascular status, making it more comfortable for patients and anesthesiologists. Morbidly obese patients, patients with cardiologic disorders, and patients with pulmonary obstructive airway disease need further studies to show if they would benefit from these differences. Additionally, it is more comfortable for the surgeon with little challenges added in the initial puncture.

Is the supine position superior to the prone position for percutaneous nephrolithotomy (PCNL)?

The objective of this study is to update the two previous meta-analyses in order to evaluate the efficacy and safety of percutaneous nephrolithotomy (PCNL) for patients in the prone position versus supine position. An electronic database search of MEDLINE, EMBASE, google scholar, and the Cochrane library was performed up to June, 2013. All studies comparing prone with supine position for PCNL were included. The outcome measures were stone-free rate, operative time, complication and hospital stay. Two randomized controlled trials (RCTs) and 7 non-RCTs, including 6,413 patients (4,956 patients in the prone position group and 1,457 patients in the supine position group), met the inclusion criteria. Meta-analysis of extractable data showed that PCNL in the supine position was associated with a significantly shorter operative time (WMD: 21.7; 95% CI 2.46-40.94; p = 0.03) but lower stone-free rate (OR: 1.36; 95% CI 1.19-1.56; p < 0.0001) than PCNL in the prone position. There was no difference between the two positions regarding hospital stay (WMD = 0.05; 95% CI -0.16-0.25; p = 0.66) and complication rate (OR: 1.1; 95% CI 0.94-1.28; p = 0.24). In conclusion, the present study found different results from the two previous meta-analyses results regarding stone-free rate; PCNL in the supine position had a significantly lower stone-free rate than that in prone position.

Percutaneous Nephrolithotomy in Autosomal Dominant Polycystic Kidney Disease: Is it Different from Percutaneous Nephrolithotomy in Normal Kidney?

OBJECTIVES

Nephrolithiasis has been reported in 20-28% of patients, of whom 50% are symptomatic for stone disease and 20% require definite urologic intervention. The management of nephrolithiasis includes oral alkali dissolution therapy, extracorporeal shock wave lithotripsy and surgical treatment. In such patients, percutaneous nephrolithotomy (PNL) as a method of stone treatment has been reported in few cases with limited experience. The aim of this study is to present our experience of PNL in autosomal dominant polycystic kidney disease (ADPKD) and assessing the outcome results.

MATERIAL AND METHODS

From 2002 to 2011, 22 patients (26 renal units) suffering from ADPKD with stone were managed by PNL. Demographic characteristics, operative parameters and postoperative complications were recorded and analysed.

RESULT

The overall success rate of PNL was 82.1% and PNL with extracorporeal shock wave lithotripsy for clinically significant residual fragments was 92.85% respectively. The hematuria required blood transfusion (n = 9), postoperative fever due to cyst infection (n = 4) and paralytic ileus (n = 3) were recorded.

CONCLUSION

The PNL in ADPKD PNL is safe and effective but have more postoperative complications such as bleeding requiring transfusions, fever due to cyst infection and paralytic ileus.

Percutaneous nephrolithotomy guided solely by ultrasonography: a 5-year study of >700 cases

OBJECTIVE

To evaluate the safety and efficacy of percutaneous nephrolithotomy (PCNL) solely guided by ultrasonography (US).

PATIENTS AND METHODS

From May 2007 to July 2012, 705 24-F-tract PCNL procedures were performed (679 patients, of whom 26 had bilateral stones). Calyceal puncture and dilatation were performed under US guidance in all cases. The procedure was evaluated for access success, length of postoperative hospital stay, complications (modified Clavien system), stone clearance and the need for auxiliary treatments.

RESULTS

The mean (sd) operating time was 66 (25) min, with a mean (sd) postoperative hospital stay of 3.98 (1.34) days. The patients experienced a mean (sd) haemoglobin level decrease of 2.24 (2.02) g/day and the overall stone-free rate at 4 weeks after surgery was 92.6% in patients with a single calculus and 82.9% in patients with staghorn or multiple calculi. Auxiliary treatments, including shockwave lithotripsy in 52 patients, re-PCNL in 41 patients and ureteroscopy in 18 patients, were performed 1 week after the primary procedure in 111 (15.7%) cases for residual stones >4 mm in size. The sensitivities of intra-operative US-guidance and flexible nephroscopy for detecting significant residual stones and clinically insignificant residual fragments were 95.3 and 89.1%, respectively. There were 94 grade 1 (13.3%), 17 grade 2 (2.4%), and two grade 3 (0.3%) complications, but there were no grade 4 or 5 complications.

CONCLUSION

Total US-guided PCNL is safe and convenient, and may be performed without any major complications and with the advantage of preventing radiation hazards and damage to adjacent organs.

Supine lithotomy versus prone position in minimally invasive percutaneous nephrolithotomy for upper urinary tract calculi

OBJECTIVE

To compare operative time, safety and effectiveness of minimally invasive percutaneous nephrolithotomy (MPCNL) in the supine lithotomy versus prone position.

METHODS

Between January 2008 and December 2010, a total of 109 consecutive patients with upper urinary tract calculi were enrolled and randomly divided into group A (53 patients, supine lithotomy position) and group B (56 patients, prone position). The MPCNL procedures were performed under the guidance of real-time grayscale ultrasound system. The preoperative characteristics, intraoperative and postoperative parameters were analyzed and compared.

RESULTS

All patients were successfully operated. There was no significant difference between the two groups in stone-free rate (group A 90.1 vs. group B 87.5%, p = 0.45), mean blood loss, number of access tracts, calyx puncture, mean hospital stay (group A 6 ± 1.1 vs. group B 6 ± 1.5 days, p = 0.38) and complications. But the operative time was significantly shortened in supine lithotomy position (group A 56 ± 15 vs. group B 86 ± 23 min, p < 0.001).

CONCLUSIONS

The effectiveness and safety of the supine lithotomy position for MPCNL were similar to the prone position. However, the supine lithotomy position has an important advantage of reducing the operative time. The supine lithotomy position could be a good choice to perform MPCNL.

[Anatomical radiology of the descending colon in the left pararenal space: about 1084 cases]

AIMS

Due to the severity of colonic injuries and their frequency on the left side, we study relationships between the left kidney and the descending colon to identify subjects at risk of colonic perforation during percutaneous surgery of the left kidney.

MATERIAL AND METHODS

Over a period of 3 years we exploited abdominal CT scans for 1084 patients in both sexes without any visceral or parietal lesions. We studied the situation and relationships of the lumbar part of the descending colon in the left pararenal space using a conventional grid technique.

RESULTS

The preferential site of the colon in both sexes was laterorenal in 55.8% of cases. We also found the descending colon in a posterolateral situation in 21.1% of cases, and in an anterolateral situation in 14.8% of cases. In women, the posterolateral situation was twice more common than in men, but we did not observe any post-renal situation. Laterorenal and posterolateral situations were the most frequent in patients less than 50 years; while beyond this age 70.1% of subjects had a laterorenal type.

CONCLUSION

Sex and age affect topographic variations of the lumbar part of the descending colon in the left pararenal space. Although they are rare or aberrant, some locations exist and should not be ignored by the operator. These locations are risk factors of colonic lesion during percutaneous approach of the left kidney.

[Learning of percutaneous nephrolithotomy in supine position. An observational multicenter study]

OBJECTIVE

To prospectively study the post-operative results and complications of percutaneous nephrolithotomy (PNL) in supine position to assess difficulty of learning it and how experience affects the results. To establish a relative comparison with the data published in the literature on the prone position.

MATERIAL AND METHODS

A prospective observational multicenter study on PNL in Valdivia position or in its Galdakao variant was performed. Demographic variables and specific variables related to the lithiasis were collected. Technical aspects, surgery time, success rate and complications according to the Clavien-Dindo classifications were assessed.

RESULTS

A total of 335 PNL in supine position conducted in 13 Spanish centers were registered from September 2008 to June 2011. The man:woman ratio was 1:1.28 and mean age 51.3+14.5 years. 211 (63%) cases were performed by urologists with experience in >50 cases and 124 (37%) by urologists with less experience. Mean operation time was 113.3 ± 46.4 min, 106.6 ± 38.2 for the experienced ones vs. 124.9 ± 56.2 in the novice ones (P<.002). No difference was detected in the mean size of the lithiasis. However, in the experienced group, there was a greater proportion of coraliform cases and multiple lithiasis than in the novice group (P<.001). Success rate evaluated as total absence of lithiasic residuals was 69.6%, without differences between groups (68.2 vs. 71.8%). In 102 (30.6%) patient had residual lithiasis and 60 (17,9%) required complementary treatment. Relative global success rate was 82.1% and complications rate 25.4%, without detecting differences between groups. However, the novel group had more major complications (P>.001).

CONCLUSION

The PNL in supine position is obtaining rapid and consolidated diffusion in our setting and its effectiveness and safety seems to be equivalent to that described in the literature for PNL in prone position. It is possible to obtain good results with a modest learning curve. The rate of greater complications associated to the procedure decreases with experience.

The "visual dilator system": initial experimental evaluation of an optical tract dilation technique in percutaneous nephrolithotomy

BACKGROUND AND PURPOSE

Ascertaining the optimal depth of dilator progression is a crucial factor during tract dilation in percutaneous nephrolithotomy. Dilation is generally guided under fluoroscopy, ultrasonography, or combination of both techniques, and it is still difficult to prevent overdilation causing perforation and vascular injury or underdilation causing difficulty in establishment of access. Thus, improvements in dilation technique bears clinical significance. Our aim was to evaluate the feasibility in an animal model of using the "visual dilator system" for optimal percutaneous tract dilation under real-time visual guidance.

MATERIALS AND METHODS

The visual dilator system consisted of a transparent hollow dilator made of polyvinyl chloride and a rigid ureteroscope inserted within its lumen. The ureteroscope was connected to a standard endoscopic camera system. The dilator system backloaded with an access sheath was passed over a guidewire to dilate the tract and position the access sheath under visual guidance. Saline was used as irrigation to maintain clarity during dilation. The dilation technique was implemented to establish percutaneous access tract in six PCNL simulator models made from fresh porcine kidney placed inside an eviscerated chicken carcass and four female swine (eight kidneys) to experimentally evaluate its feasibility and efficacy.

RESULTS

All tracts were successfully established with dilation through the intervening tissue layers, approach into the target calix, as well as access sheath placement being visually monitored through the dilator wall to confirm accuracy. All procedures were free of dilation-related complications such as collecting system perforation, excessive bleeding (in-vivo model), or loss of access. The limited number of animal models and lack of randomized comparative study with other dilator modalities were major drawbacks of the study.

CONCLUSIONS

The study demonstrates feasibility of percutaneous access tract dilation using a Visual dilator system. This technique can provide visual confirmation of accuracy in dilation to improve safety and efficacy of the procedure.

[Simultaneous antegrade-retrograde therapy for renal calculi]

The current guidelines recommend percutaneous nephrolithotomy (PCNL) as the first choice procedure for large stone masses. Complex stone situations, such as formed stones or large peripheral stone masses, however, often necessitate several access points and multiple stage procedures. In such cases open surgical stone removal is often used. An alternative is simultaneous antegrade-retrograde stone therapy in which PCNL is combined with flexible ureterorenoscopy (fURS). Both procedures complement each other in that fURS allows access to narrow calyces and PCNL the simple removal of buried concretions via the percutaneous shaft without excessive disintegration. Even difficult stone situations can be resolved simultaneously. Disadvantages are the high personnel and instrumental involvement (two endoscopic procedures with two endoscope towers and two operators) which is not adequately reflected in the diagnosis-related groups (DRG) remuneration system. Additionally simultaneous stone treatment is normally carried out in the supine lithotomy position so that even an experienced percutaneous surgeon is confronted with a new situation and a certain learning curve. Our own experiences and that of other working groups show, however, that the simultaneous approach represents an attractive and effective addition to minimally invasive stone therapy if the appropriate equipment and corresponding expertise are available.

Percutaneous nephrolithotomy in the supine position: Safety and outcomes in a single-centre experience

Objectives

To assess the feasibility of performing percutaneous nephrolithotomy (PCNL) with the patient supine. Although PCNL with the patient prone is the standard technique for treating large (>2 cm) renal stones including staghorn stones, we evaluated the safety and efficacy of supine PCNL for managing large renal stones, with special attention to evaluating the complications.

Patients and method

In a prospective study between January 2010 and December 2011, 54 patients with large and staghorn renal stones underwent cystoscopy with a ureteric catheter inserted, followed by puncture of the collecting system while they were supine. Tract dilatation to 30 F was followed by nephroscopy, stone disintegration using pneumatic lithotripsy, and retrieval using a stone forceps. All patients had a nephrostomy tube placed at the end of the procedure. The results were compared with those from recent large series of supine PCNL.

Results

The median (range) operative duration was 130 (90–210) min, and the mean (SD) volume of irrigant was 22.2 (3.7) L. One puncture was used to enter the collecting system in 51 renal units (94%), while three units (6%) with a staghorn stone needed two punctures. The stone clearance rate was 91%, and five patients had an auxiliary procedure. There were complications in 15 patients (28%). All patients were stone-free at a 3-month follow-up.

Conclusion

Supine PCNL is technically feasible; it has several advantages to patients, urologists and anaesthesiologists. It gives stone-free rates and a low incidence of organ injury comparable to those in standard prone PCNL.

Free-flank modified supine vs. prone position in percutaneous nephrolithotomy: A prospective randomised trial

OBJECTIVE

To compare the technical aspects, operative time, safety and effectiveness of percutaneous nephrolithotomy (PCNL) in the free-flank modified supine position (FFMSP) vs. the standard prone position (SPP).

PATIENTS AND METHODS

Seventy-seven patients (47 men and 30 women) with renal stones were enrolled and systematically randomised into two groups, A (39 patients) treated using the FFMSP, and B (38 patients) in the SPP. The outcome was considered as a cure (successful procedure) if the patient became stone-free or had residual fragments of <4 mm in diameter. The operative time (from the induction of anaesthesia to the removal of the endotracheal tube) was measured and any operative complications or conflicts were recorded. The different variables were compared and analysed between the groups.

RESULTS

Patients in both groups had comparable preoperative clinical data and there were no significant differences in the preoperative clinical characteristics. The procedure was successful in 84.6% and 84% of group A and B, respectively. The operative time was significantly longer in group B (SPP) than A (FFMSP). There was no significant difference between the groups in fluoroscopy time and patients' outcome.

CONCLUSIONS

The FFMSP (with a cushion under the ipsilateral shoulder) has similar efficacy and safety as the SPP for PCNL and is associated with a significantly quicker operation.

Positions for percutaneous nephrolithotomy: Thirty-five years of evolution

Objectives

To present the chronological development of the different positions described for percutaneous nephrolithotomy (PCNL), in an attempt to identify the reasons for their development and to highlight their specific advantages and disadvantages.

Methods

Previous reports were identified by a non-systematic search of Medline and Scopus.

Results

The classic prone position for PCNL was first described in 1976. The technique was gradually standardised and PCNL with the patient prone became the generally accepted standard approach. In the next 35 years many other positions were described, with the patient placed prone, lateral or supine in various modifications. Modifications of the classic prone position in the early 1990s aimed to provide the option of a simultaneous retrograde approach during the procedure. As PCNL became more popular the lateral position was first described in 1994, to allow the application of PCNL to patients who were unable to tolerate being prone because of their body habitus. The supine position for percutaneous access was originally described even before 1990, but become more popular after 2007 when the Galdakao modification was reported. Several other modifications of the supine position have been described, with the latest being the flank-free modified supine position, which allows the best exposure of the flank among the supine positions. Each position has its specific advantages and disadvantages.

Conclusion

Urologists who perform PCNL should be familiar with the differences in the positions and be able to use the method appropriate to each case.

Flank free modified supine position: A new modification for supine percutaneous nephrolithotomy

OBJECTIVES

Percutaneous nephrolithotomy (PCNL) is the standard management for large and/or complex urolithiasis, but the standard patient position for PCNL is undecided. With the patient prone PCNL has several drawbacks, while when supine, as described previously, PCNL has mechanical limitations. We describe a modification that aims to overcome these limitations and provide easy access comparable to that in the prone position.

PATIENTS AND METHODS

This prospective study was carried out at the Urology Department, Zagazig University, Egypt, from October 2008 to March 2011, and included 78 patients (48 men and 30 women). First the patient was placed supine and then in the 'flank-free modified' supine position. The distance between the last rib and the iliac crest in the posterior axillary line was measured in both positions.

RESULTS

The mean age of the patients was 40.8 years, the mean (SD) stone diameter was 3.4 (0.7) cm, the number of right/left stones was 34/44, and mean body mass index was 28.8 kg/m(2). The mean (SD) increase in the distance between the last rib and the iliac crest in the posterior axillary line in the flank free modified supine position vs. the previous supine position was 12 (0.8) mm.

CONCLUSION

The flank-free modified supine position increases the distance between the last rib and the iliac crest, and, together with the absence of a cushion under the flank, provides ample space for puncture, dilatation, multiple tracts and manoeuvrability of the system with the nephroscope.

[Prone and supine position for percutaneous nephrolithotomy: is it necessary to change the operative technique?]

PURPOSE

To assess the safety and effectiveness of percutaneous nephrolithotomy performed in the supine position. To investigate whether the change in operative technique, between prone and supine position, is easy.

METHOD

Thirty patients who underwent percutaneous nephrolithotomy, by one surgeon in one hospital, were studied retrospectively. The eight first cases were performed in prone position, and the following 22 patients were operated in supine position according to Valdivia's operative technique. Data were analyzed with t-test. We considered P<0.05 as significant.

RESULTS

Surgical complication rate, transfusion rate and fever rate were the same for both groups. Success rate was 72% in supine position group and 63% in prone position group (P>0.05). These results were comparable with the data of the literature. Only operative time was shorter in supine position group with significant statistical difference (P=0.02).

CONCLUSION

In our experience, percutaneous nephrolithotomy in the supine position was safe and efficient, and outcomes were similar to that in the prone position. Learning curve was easy and fast.