|Year : 2022 | Volume
| Issue : 1 | Page : 35-41
Single versus multiple mini-tract percutaneous nephrolithotomy for staghorn renal stone: A single-center study
I-Chen Tsai1, Zhi-Hao Chen1, Kau-Han Lee1, Chien-Liang Liu1, Steven K Huang1, Allen W Chiu2
1 Division of Urology, Department of Surgery, Chi Mei Medical Center, Tainan, Taiwan
2 Department of Urology, Mackay Memorial Hospital; School of Medicine, National Yang-Ming University, Taipei, Taiwan
|Date of Submission||08-Oct-2020|
|Date of Decision||22-Jul-2021|
|Date of Acceptance||14-Sep-2021|
|Date of Web Publication||02-Mar-2022|
Dr. Kau-Han Lee
Division of Urology, Department of Surgery, Chi Mei Medical Center, No. 901, Zhonghua Rd. Yongkang Dist., Tainan 71004
Source of Support: None, Conflict of Interest: None
Purpose: Percutaneous nephrolithotomy (PCNL) is the standard procedure used for large kidney stones, and multiple tracts of PCNL are applied to achieve better stone clearance. However, the creation of multiple tracts may have the potential risk of bleeding and higher complication rates compared with single-tract procedures. We reviewed our experience managing staghorn calculi with multiple tracts compared with a single tract. Materials and Methods: Records of 36 patients with staghorn calculi who underwent PCNL at our institution between January 2018 and April 2020 were reviewed retrospectively. Nineteen patients were managed by single-tract access (Group 1), and 17 patients underwent multiple-tract access (Group 2). Both groups were compared in terms of perioperative findings and postoperative outcomes. Results: The mean number of percutaneous accesses in the multiple-tract group was 2.88, with most patients requiring two tracts. The mean duration of fluoroscopy screening and operative time was longer in Group 2. Stone-free rates were 59% and 70.5% in Groups 1 and 2, respectively. The mean hospital stay was similar in both groups. Complications included blood transfusion, resulting from a hemoglobin drop of 2.15 ± 0.96 and 1.59 ± 0.69 g/dL in Groups 1 and 2, respectively. Mean pre- and post-operative creatinine concentrations were 1.212 and 1.211 mg/dL in Group 1 and 1.206 and 1.157 mg/dL in Group 2. Mean changes in creatinine values were not statistically significant between the groups. Clavien–Dindo Classification Grade II complications included urosepsis and blood transfusion, which occurred in five patients in Group 1 and three in Group 2. Pseudoaneurysm attributed to Grade III complications occurred in one patient in Group 1. Conclusion: Multiple-tract access during PCNL is a safe and efficient method to manipulate staghorn kidney stones. Mini PCNL with multiple-tract access is a successful alternative to deal with staghorn stones involving multiple calyces.
Keywords: Mini percutaneous nephrolithotomy, multiple tracts, staghorn stones
|How to cite this article:|
Tsai IC, Chen ZH, Lee KH, Liu CL, Huang SK, Chiu AW. Single versus multiple mini-tract percutaneous nephrolithotomy for staghorn renal stone: A single-center study. Urol Sci 2022;33:35-41
|How to cite this URL:|
Tsai IC, Chen ZH, Lee KH, Liu CL, Huang SK, Chiu AW. Single versus multiple mini-tract percutaneous nephrolithotomy for staghorn renal stone: A single-center study. Urol Sci [serial online] 2022 [cited 2022 May 21];33:35-41. Available from: https://www.e-urol-sci.com/text.asp?2022/33/1/35/338933
| Introduction|| |
Staghorn calculi are branched stones that involve more than two calyces and occupy a large portion of the collection system. Failure to eliminate staghorn calculus may destroy the parenchyma and kidney function and cause life-threatening sepsis. Therefore, complete removal and clearance rates are mostly considered when dealing with staghorn stones.
Percutaneous nephrolithotomy (PCNL), which is preferred for patients with staghorn stones, is a safe and successful technique., Compared with other treatments, such as open surgery, extracorporeal shock wave lithotripsy (ESWL), and combined surgery, PCNL has a lower morbidity rate and higher stone clearance rate.
Since PCNL is a successful method for removing renal stones, modifications, and refinements such as slender nephroscopes have been developed, further enhancing the outcome and decreasing morbidity. Miniaturized PCNL (mini PCNL, mPCNL) is defined as using sheaths between 11 and 21 Fr. In contemporary literature, mPCNL is considered safe and an effective alternative to conventional PCNL for adult and pediatric patients. Furthermore, even in anomalous kidneys, such as the horseshoe, polycystic, and transplanted kidneys, mPCNL is safe and feasible.
However, longer operation times, higher irrigation pump pressure, and multiple tracts become necessary methods for achieving complete stone removal as the size and complexity of renal stones increase. Controversy remains whether creating multiple percutaneous tracts can cause more bleeding and higher complication rates than procedures requiring a single tract. Moreover, mPCNL has been questioned in treating patients with large complex staghorn stones due to the smaller access sheath, leading to comparatively reduced visibility and stone-free rate (SFR). This study reviewed the experience of managing staghorn calculi with multiple-tract mPCNL and evaluates that multiple-tract mPCNL approaches are appropriate and effective in achieving stone-free status in more complex staghorn stones.
| Materials and Methods|| |
Patient enrollment and data collection
Between January 2018 and April 2020, 232 patients underwent PCNL at Chi-Mei Medical Center. This study reviewed 36 patients who underwent PCNL for staghorn stones. The inclusion and exclusion criteria are listed in [Figure 1]. Patients who received single- or multiple-tract mPCNL depended on the stone complexity of their computed tomography (CT) images before the operation. In addition, 19 patients who underwent the single mini-tract (<21-Fr sheath) percutaneous method (Group 1) were retrospectively compared with 17 patients who required multiple (≥2) mini tracts (Group 2) in a single surgical setting.
Patient demographics, including age, gender, height, weight, body mass index (BMI), preoperative hemoglobin (Hb), preoperative serum creatinine, estimated glomerular filtration rate, urine pH, previous procedures, stone complexity (S. T. O. N. E score), and stone burden (cm3), were recorded. Clinical outcomes included SFRs, operation time, hospital stay length, complications, postoperative Hb and creatinine levels, and pain control dosages.
In addition to brief history-taking, the preoperative workup included blood analysis (e.g., serum creatinine and Hb measurements, platelet count, and coagulation screening). Radiological evaluation included plain radiography of the kidney, ureter, and bladder (KUB) and ultrasonography. Furthermore, noncontrast abdominal CT was performed to identify the anatomy of the renal collecting system and stone location, size, and hardness.
Surgical procedures and postoperative evaluation
First, the patient was placed in the lithotomy position after general anesthesia. Next, the 5-Fr ureteral catheter was retrogradely inserted into the renal pelvis for contrast medium performed by cystoscopy. The patient was then placed into a prone position; the ureteropelvic junction, renal pelvis, and calyx were appropriately identified by injecting the contrast medium by catheter and biplane fluoroscopy (C-arm) guidance. In addition, percutaneous punctures were made by the urologist to the targeted calyx using an 18G puncture needle on the posterolateral avascular line. The number and location of the puncture site depended on the patient's anatomy and the stone position during the operation. The tract was dilated up to 16-or 21-Fr after the correct position was confirmed.
Moreover, mPCNL was performed using a 12-Fr nephroscope and a 16-Fr peel-away sheath with a normal saline irrigation pump (150–200 cm H2O). The stones were first fragmented with pneumatic lithotripsy. Then, the fragmented stones were washed out by normal saline irrigation with a vacuum cleaner effect. Once the stone-free condition was confirmed by fluoroscopy (C-arm) and endoscopy, an adequately sized JJ stent was placed in an antegrade manner. Notably, JJ stent insertion was performed in every case.
Postoperative KUB was performed 24–48 h after the operation to evaluate the JJ stent position and residual stone size and calculate the SFR in each case. The JJ stent was placed for approximately 2–4 weeks. KUB was reperformed after JJ stent removal. Notably, the stone-free status was defined as residual stone length 4 mm on the KUB after JJ stent removal. Hb, creatinine, and urine analysis were also performed within 48 h after the operation. Another ESWL, a second PCNL, and ureterorenoscopic stone manipulation were performed if the residual stone was >0.4 cm. All patients were followed up with KUB, urinalysis, and renal function tests within at least 3 months.
An independent-sample t-test was applied for continuous variables (e.g., patient characteristics and perioperative parameters). Chi-square or Fisher's exact tests was applied for analyzing the categorical data between the two groups. A P < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS for Windows (v. 18; IBM Corp., Armonk, NY, USA). In addition, the OsiriX software (Pixmeo, Bernex, Switzerland) was used to calculate the stone volume. The stone area was circled at every cut of the CT image. The OsiriX software helped estimate the whole volume (cm3) of the staghorn stone. Finally, the surgeon could locate the ideal site to puncture through before the surgery based on CT images and OsiriX.
| Results|| |
Thirty-six patients with staghorn calculi (men, 19; women, 17) were treated with two mPCNL types, and 19 and 17 patients were treated with single- and multiple-tract PCNL, respectively. The mean stone size was 14.82 cm3; a significant difference in stone size was found before surgery (12.67 ± 8.06 and 17.23 ± 10.49 cm3 in Groups 1 and 2, respectively; P = 0.048). In addition, the S. T. O. N. E. score in Group 2 was significantly higher (10.6 ± 1.3 vs. 8.4 ± 1.7; P = 0.001). No difference in other patients' characteristics was noted [Table 1].
[Table 2] lists the comparison of operative details and postoperative parameters. The fluoroscopic and operative times were significantly longer in Group 2 (P < 0.001). The postoperative Hb drop was 2.15 ± 0.96 and 1.59 ± 0.69 mg/dL in Groups 1 and 2, respectively (P < 0.05). Furthermore, no statistically significant differences were noted in the SFR or the rate of ancillary procedures, and no significant changes were noted in creatinine changes. However, renal function improved in both groups. The pain level determination was judged by the dosage of morphine or tramadol, which was intravenously administered. Both groups included two patients who required more than two doses of morphine or tramadol during hospitalization.
Comparison of tract details, including the stone-free cases and average stone complexity and complications, is listed in [Table 3]. The average multiple tracts used was 2.8. The complication was classified as Clavien–Dindo. Patients in this study who experienced fever (≥38.5°C) were related to urinary tract infections. Blood transfusion requirement was defined as postoperative symptomatic anemia (Hb level, <8 g/dL). All patients recovered after treatment with intravenous antibiotics and other supportive measures. Furthermore, angiography was performed owing to persistent bleeding for patients with pseudoaneurysm in the single-tract group. Finally, the patient recovered fully after transarterial angioembolization treatment.
|Table 3: Comparison of tract details and complications (Clavien-Dindo classification)|
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| Discussion|| |
PCNL is the preferred first-line treatment for large burden stones (>2 cm) according to the American Urological Association and the European Association of Urology guidelines. A stone clearance rate of 74%–83% was achieved using this surgical approach with acute complication, transfusion, and ancillary rates of 15%, 14%–24%, and 18%, respectively., Moreover, PCNL is the preferred management for most complex kidney stones compared with open, ESWL, RIRS, or combined surgery. As the complexity and stone burden increase, multiple-tract PCNL is considered a method for increasing SFRs.
PCNL could be categorized as standard, mPCNL, ultra-mPCNL, and micro-mPCNL based on the different sheath diameters. The standard, mPCNL, ultra-mPCNL, and micro-mPCNL sheath ranges from 24–30, 14–21, 11–13, to 4.8 Fr, respectively. In addition, mPCNL was mostly used previously in cases of pediatric urinary or small kidney stones in adults. However, multiple-tract mPCNL became a feasible option for treating renal staghorn stones with improvements in equipment and surgical techniques. Furthermore, the idea of multiple-tract mPCNL was based on anatomy limitations. Verma et al. insisted that pelvicalyceal anatomy variables (e.g., infundibular width, intercalyceal angle, and pelvicalyceal system surface area) affected the number of punctures. All patients in this study were categorized into two groups based on the stone volume, anatomical variables, Hounsfield unit, and occupied calyx before the operation, which the same experienced operator in mPCNL evaluated. The tracts used in Group 2 were decided during the operation, owing to the reduction in operation time to avoid sepsis and reach maximal stone clearance.
Furthermore, RIRS has the advantages of less postoperative pain, lower blood transfusion rate, shorter length of hospital stays, and a lower rate of other complications than the same situation of dealing with staghorn stones by mPCNL. However, its SFR is lower than mPCNL. The ancillary procedure rate increases to achieve an acceptable SFR as the stone burden and complexity increase.
This study established the first endpoint as stone-free status based on the KUB at the time of JJ stent removal. The SFR was achieved in 12 patients (70.5%) and increased to 83.5% after secondary ESWL. This result is comparable to that of Singla et al.; they studied the outcome of multiple-tract PCNL and reported that complete clearance was achieved in 70% and 89% of patients initially and after the second procedure, respectively. In addition, in treating staghorn calculi, Zhong et al. used the multiple-tract mPCNL in a single session and achieved a clearance rate of 82.8%. According to the European Association of Urology guidelines, evidence exists that fragments >2 mm are more likely to grow, whereas fragments >5 mm are more likely to require intervention than smaller ones. In addition, Arvind et al. declared that a small fragment (<5 mm) may get expelled by a JJ stent; Zhu et al. defined stone-free status as a ≤3-mm residual fragment or no residual stone burden. However, they examined the KUB or noncontrast CT for the residual stones 14 d after surgery. Furthermore, Rashid et al. defined stone-free status in children as residual fragments <4 mm on KUB. Considering these studies and those of patients who had JJ stent insertion after surgery, stone-free status was defined as residual stone <4 mm on the KUB when the JJ stent was removed.
The most concerning complications observed with the multiple-tract method were bleeding and blood transfusion compared with single-tract procedures. In this study, the postoperative drop in Hb level was lower in the multiple-tract group with a statistically significant difference. Moreover, in Groups 1 and 2, three (15.8%) and two (11.8%) patients, respectively, required blood transfusions. This result was different from a previous study by Hegarty and Desai, who showed that the mean Hb drop was similar in the two groups (2.08 vs. 2.32 g/dL for single and multiple tracts, respectively). Akman et al. also observed that the mean drop in postoperative Hb level was significantly higher in the multiple-(2.5 ± 1.6 g/dL) than single-(2.1 ± 1.7 g/dL) tract group. Furthermore, Martin et al. reported that the transfusion rates also differed significantly, with 20% and 41.6% requiring transfusion in patients with less than or more than two tracts for stone clearance. The reason for the lower Hb drop in the multiple-tract group may attribute to the puncture site and other smaller tracts used. The basic principle of the puncture is to determine the shortest route from the skin to the renal papilla. However, the primary access to the pelvicalyceal system remains unknown among researchers. The upper pole approach is the shortest and direct access for puncture, but the increasing chest and pleural complication rate should be considered. According to Liatisikos et al., patients in our study received infracostal (12th rib) lower or middle pole access using the angular puncture technique. Owing to the long distance between the kidney and skin, the single-tract angle becomes much steeper in reaching the other calyx, resulting in torquing the nephroscope to reach higher SFR with a wider laceration of the renal parenchyma [Figure 2]. The first puncture of all patients was made by a relatively larger mPCNL sheath (20 or 21 Fr) to reach occupied stones in the renal pelvis. In Group 2, other tracts were smaller (16 or 18 Fr) and located at the avascular line to reach the target calyx, which reduced renal trauma. However, in some group 2 cases, new tracts in a single incision were created. Therefore, this method decreased muscular and parenchymal lacerations in the kidney [Figure 2], lowering the bleeding and blood transfusion rate in the multiple-tract group.
|Figure 2: Surgical methods between groups. (a) In group 1, if the infundibular angle was sharp or the infundibular width was narrow, it was favored to cause wider laceration in renal parenchyma in order to reach another calyx. (b) In group 2, the other tracts were smaller than the main tract we first punctured. In some cases, the single incision of multiple-tract approach decreased the muscular and parenchyma laceration on the kidney|
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Other complications observed in PCNL included fever, pseudoaneurysm, urosepsis, and hemothorax or hydrothorax. In a previous study and according to the American Urological Association guidelines, the complication rate of PCNL monotherapy varied from 15% to 28.6%., As previously reported in the literature, complications between single-and multiple-tract PCNL were not significantly different. Moreover, complications categorized according to the Clavien–Dindo classification occurred in this study [Table 3]. However, these rates were similar to those in other reports using multiple-tract PCNL. The data in our study also revealed no differences in the complication rate between single- and multiple-tract mPCNL but showed that grade I and II complications could be easily treated by intravenous antibiotics and blood transfusion without permanent injuries. Grade III complications include pseudoaneurysm or other chest injuries, including pneumothorax, hemothorax, and hydrothorax. The only patient who had pseudoaneurysm was treated with angiography and discharged on the postoperative day 4 with fully recovery. The study by Singla et al. found 4.2% hydrothorax, 2.4% angioembolization, and 0.6% hemothorax cases in 149 patients. No chest injury was observed in this study because of the angular puncture with the approach of middle or lower calyx access. Desai et al. have suggested that punctures above the 11th rib should be avoided because they are associated with a higher (16-fold greater than supra-12th access) incidence of chest complications. A previous study reported that an intercostal puncture above the 12th rib carries a 2.8%–12% risk of pleural injury and chest complications. In addition, Olvera-Posada et al. observed that patients who were older or had more comorbidities were more likely to have staghorn calculi and had longer operative time and length of hospital stay. Age (≥55 years) and upper pole access were independent predictors of major complications in their study. PCNL tract number and other characteristics (e.g., stone composition, BMI, or previous PCNL) were unassociated with the complication rate. These findings are comparable with those of our study, indicating that multiple-tract PCNL is a safe and feasible option for treating staghorn calculi.
A 49-year-old female presented with sudden right flank pain, and the KUB accidentally showed a left complete renal stone. After treating the right ureteral stone, the patient decided to receive mPCNL for the left complete renal staghorn stone. The stone volume was 47.25 cm3, which was the largest in the patient's cohort. The S. T. O. N. E. score was 12, and the patient was indicated for multiple-tract mPCNL. The tract size and number used were 21-Fr*1, 17-Fr*3, and 16-Fr*1, and the total operation time was 210 min. The operative images with multiple tracts are shown in [Figure 3]a. Comparison with the pre- and postoperative KUB is shown in [Figure 3]b; stone-free status was achieved without complication. The Hb of the patient dropped from 11.1 to 10.0 g/dL without blood transfusion; moreover, the creatinine level changed from 0.69 to 0.74 mg/dL. Consequently, the patient was discharged from the ward on postoperative day 5 because she became stable. After follow-up with the patient in 3 months, no residual or new stone was noted on KUB.
|Figure 3: Images of the five-tract case. (a) These are images captured during fluoroscopy by C-arm in the 5-tract case. We only had three incision sites because 2 tracts were puncture through the previous skin incision and reached different calyx. (b) The comparison of preoperative kidney, ureter, and bladder and postoperative kidney, ureter, and bladder in this 5-tract case|
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Some limitations of this study include, first, small sample sizes; thus, larger sample size is needed to evaluate the association between tract number, stone complexity, SFR, and complication. Patients received multiple-or single-tract PCNL performed by the same experienced surgeon to minimize bias with the experience of different surgeons. Thus, a larger study population is needed for further studies. Second, evaluating actual blood loss is difficult because the blood is mixed with irrigation fluid during the operation. Therefore, postoperative Hb can only be measured to evaluate possible blood loss. However, fluid hydration and irrigation fluid may decrease Hb level, which influences blood transfusion decisions. Third, only the short-term outcome was evaluated during the admission period. Therefore, long-term follow-up of complications and stone recurrence should be performed in the future.
| Conclusion|| |
Multiple-tract mPCNL is a safe and effective option for treating staghorn calculi. As stone complexity or volume increases, the multiple-tract method leads to a high SFR and affordable cost for patients. Moreover, multiple-tract mPCNL also exhibited an acceptable complication rate in the single-tract group. The morbidity rate (bleeding with blood transfusion) is under debate but was lower than the single-tract group in this study. Conclusively, multiple-tract mPCNL is a successful alternative method for dealing with more complex or complete staghorn calculi.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]