Staghorn calculi of the kidney: classification and therapy

Prediction of percutaneous nephrolithotomy outcomes and flexible ureteroscopy outcomes using nephrolithometry scoring systems

BACKGROUND

Kidney stones account for a high proportion of urological emergencies. The main objective of this paper is to evaluate the predictive ability of five scoring systems for overall stone-free status and postoperative complications after percutaneous nephrolithotomy and retrograde ureteroscopy.

MATERIALS AND METHODS

This study retrospectively analysed 312 cases of kidney stone patients between January 2021 and May 2022 at our centre. Multivariate logistic regression as well as ROC curves were applied to determine the ability to evaluate each scale to predict stone-free rates and postoperative complications.

RESULTS

179 patients have undergone PCNL. After multivariate logistic regression, the S.T.O.N.E score and history of ipsilateral renal surgery were predictive of stone-free status, and the predictive power of the S.T.O.N.E score was higher than that of history of ipsilateral renal surgery. Grade 1 complications were considered to be related to Guy's score and grade 2 complications were considered to be related to history of diabetes mellitus. 133 patients have undergone f-URS. After multivariate logistic regression analysis, the modified S-ReSC score, RUSS score, and R.I.R.S score were predictive of stone-free status, with the R.I.R.S score being the strongest predictor. Evidence of grade 2 complications was considered to be related to abnormal renal function.

CONCLUSION

For PCNL, the S.T.O.N.E score had the best efficacy in predicting stone-free status, and the Guy's score had the best efficacy in predicting postoperative complications; for f-URS, the R.I.R.S score had the best efficacy in predicting stone-free status, and no scoring system predicted postoperative complications.

Morphometry scores: Clinical implications in the management of staghorn calculi

Due to their large size, rapid growth, and attendant morbidity, staghorn calculi are complex clinical entities that impose significant treatment-related challenges. Moreover, their relative heterogeneity-in terms of both total stone burden and anatomic distribution-limits the ability to standardize their characterization and the reporting of surgical outcomes. Several morphometry systems currently exist to define the volumetric distribution of renal stones, in general, and to predict the outcomes of percutaneous nephrolithotomy; however, they fall short in their applicability to staghorn stones. In this review, we aim to discuss the clinical utility of morphometry systems and the influence of pelvicalyceal anatomy on the management of these complex calculi.

How practical is the application of percutaneous nephrolithotomy scoring systems? Prospective study comparing Guy's Stone Score, S.T.O.N.E. score and the Clinical Research Office of the Endourological Society (CROES) nomogram

Objective

To prospectively compare the Guy’s Stone Score (GSS), S.T.O.N.E. [stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence or stone density (E)] score and the Clinical Research Office of the Endourological Society (CROES) nephrolithometric nomogram to predict percutaneous nephrolithotomy (PCNL) success rate and assess the correlation with perioperative complications.

Patients and methods

We prospectively evaluated all consecutive PCNL patients at our institute between 1 November 2013 and 31 May 2015. The above scoring systems were applied to preoperative non-contrast computed tomography and the practical difficulties in such applications were noted. Perioperative complications and the stone-free rate (SFR) were also recorded. Receiver operating characteristic curves were drawn and the areas under curves were compared and appropriate statistical analysis done.

Results

In all, 48 renal units were included in the study. The overall SFR was 62.2%. The presence of staghorn stones (β = 27.285, 95% confidence interval 1.19–625.35; P = 0.039) was the only significant variable associated with the residual stones on multivariate analysis. Stone-free patients had significantly lower median GSS (2 vs 4) and S.T.O.N.E. scores (6 vs 10) and higher median CROES scores (83% vs 63%) (all P < 0.001) compared to residual-stone patients. All scoring systems were significantly associated with SFR (all P < 0.001). There was no significant difference in the areas under curves of the scoring systems (0.858, 0.923, and 0.931, respectively). Furthermore, all scoring systems had weak correlations with Clavien–Dindo classified complications (r = 0.29, P = 0.045; r = 0.40, P = 0.005 and r = −0.295, P = 0.04, respectively). We found no standardisation for the measurement of stone dimensions, tract length, Hounsfield units, and staghorn definition.

Conclusions

All scoring systems equally predicted SFR and had a weak correlation with Clavien–Dindo complications. Standardisation is needed for the variables in which they have been found deficient.

Interobserver Reliability and Reproducibility of the Clinical Research Office of the Endourological Society Nomogram in Predicting Percutaneous Nephrolithotomy Results

OBJECTIVE

To assess interobserver reliability and reproducibility of the Clinical Research Office of the Endourological Society (CROES) nephrolithometric nomogram.

PATIENTS AND METHODS

Preoperative data and postoperative outcomes of 100 consecutive patients who underwent percutaneous nephrolithotomy were obtained. Patients' data were reviewed separately by 4 independent urologists of different academic level: an experienced attending endourologist, a graduated fellow, a young fellow, and a resident. Each rater adjusted a CROES score in all 100 patients. Interobserver reliability was analyzed by assessing intraclass correlation (ICC) and kappa coefficient among and between all different raters.

RESULTS

Assessment of interobserver reliability showed good or excellent agreement among all raters. Moderate agreement was only found between the raters for the "presence of staghorn" score. ICCs among all raters expressed excellent levels for each independent CROES parameter and reached great statistical significance. The highest correlation was noticed for "stone burden" in contrast to "presence of staghorn" parameter that showed the lowest. ICC for the final CROES score revealed good to excellent agreement among all raters and all pairs of raters.

CONCLUSION

CROES nephrolithometry is a reproducible nomogram. Reproducible results were obtained within a single institution by multiple reviewers of varying experience within a short period of time after undergoing standardized training.

Staghorn classification: Platform for morphometry assessment

Introduction:

The majority of staghorn classifications do not incorporate volumetric stone burden assessment. Accurate volumetric data can easily be acquired with the ever-increasingly available computerized tomography (CT) scan. This manuscript reviews the available staghorn stone classifications and rationalizes the morphometry-based classification.

Materials and Methods:

A Pubmed search was performed for articles concerning staghorn classification and morphometry. Twenty abstracts were shortlisted from a total of 43 published abstracts. In view of the paucity of manuscripts on staghorn morphometry (4), older staghorn classifications were analyzed with the aim to determine the most optimum one having relevance to the percutaneous nephrolithotomy (PCNL) monotherapy outcome.

Results:

All available staghorn classifications are limited with non-widespread applicability. The traditional partial and complete staghorn are limited due to non-descript stone volumetric data and considerable overlap of the intermediate ones in either group. A lack of standardized definition limits intergroup comparison as well. Staghorn morphometry is a recent addition to the clinical classification profiling of a staghorn calculus. It comprises extensive CT volumetric stone distribution assessment of a staghorn in a given pelvi–calyceal anatomy. It allowsmeaningful clinical classification of staghorn stones from a contemporary PCNL monotherapy perspective.

Conclusions:

Morphometry-based classification affords clinically relevant nomenclature in predicting the outcome of PCNL for staghorn stones. Further research is required to reduce the complexity associated with measuring the volumetric stone distribution in a given calyceal system.

An atypical case of large bowel obstruction

In Europe up to nine per cent of people suffer from renal calculi during their lifetime. Staghorn calculi are common and account for ∼11% of cases. Classic presentations include persistent loin pain, recurrent pyelonephritis or cystitis-like symptoms, renal colic or occasional haematuria. We present what we believe to be the first documented case of large bowel obstruction caused by a benign colonic stricture formed secondary to extravasation of a staghorn calculus.

Strategic lithotripsy using the Doli S EMSE 220 F-XP for the management of staghorn renal calculi

AIM

The presentation of our results using the Dornier lithotripter (Doli) S electromagnetic shockwave emitter (EMSE) 220 F-XP for the strategic management of staghorn renal calculi.

METHODS

Sixteen patients with renal staghorn stones of more than 35 mm in maximum length on plain X-rays were treated by shock wave lithotripsy (SWL) monotherapy with the Doli S EMSE 220 F-XP. Double-J ureteral stent was inserted to all prior to the first SWL treatment. Shock wave counts varied from 2,500 to 3,600 with a shock release frequency of 70-80 pulses per minute. The number of sessions varied from 2 to 6. The interval between the SWL sessions was around 1 month. Fragmentation rate of 20-25% of the stone load per session was considered a valid criterion for progressing to further SWL sessions.

RESULTS

Nine patients became stone free at the end of SWL sessions and two patients had renal stone fragments smaller than 4 mm, which were eliminated 6 months later. Two patients developed streinstrasse that was managed with ureteroscopy. Auxiliary SWL was also performed on three patients with residual ureteral calculi. The mean follow up period was 12 months. The remaining five patients underwent open surgery for incomplete stone fragmentation. No major complications developed during the follow up period. The predominant composition of stones available for analysis was struvite.

CONCLUSION

Doli S EMSE 220 F-XP can be a safe and effective treatment option for renal staghorn stones on an outpatient basis.

Combined Ureterorenoscopy and Shockwave Lithotripsy for Large Renal Stone Burden: An Alternative to Percutaneous Nephrolithotomy?

PURPOSE

To investigate the feasibility and initial outcomes of a combination of ureterorenoscopy (URS) using holmium laser lithotripsy and extracorporeal shockwave lithotripsy (SWL) in a single outpatient session for the treatment of large renal stone burdens in patients refusing or unsuitable for percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

Fourteen patients with a mean age of 52.7 years (range 34-81 years) having a mean stone burden of 847 mm2 (range 58 mm2-1850 mm2) were treated with combined URS laser lithotripsy and SWL as an alternative to PCNL. The SWL (mean 2800 shockwaves) was performed using the Storz Modulith SL-X, and flexible URS with holmium laser lithotripsy was performed either during or following SWL.

RESULTS

Ninety-three percent of the patients (13/14) were treated successfully on an outpatient basis. Two patients were rendered stone free after the initial procedure alone (14%). Overall, including secondary outpatient treatment with a second session of URS alone (N = 7) URS and SWL (N = 1), SWL (N = 1), or oral alkalinization therapy (N = 1), the stone-free rate was 76.9% (10/13). One patient was excluded secondary to death from unrelated causes after the initial procedure, and the success rate (residual fragments <4 mm) was 84.6% (11/13). The two treatment failures included one patient who required a third URS procedure and one patient who developed urosepsis necessitating nephrostomy-tube placement who underwent subsequent PCNL.

CONCLUSIONS

In comparison with traditional approaches using PCNL and second-look nephroscopy, single-session combined URS and SWL with a second outpatient procedure may offer equivalent results with decreased morbidity in carefully selected patients.

Treatment of complete staghorn stones: a prospective randomized comparison of open surgery versus percutaneous nephrolithotomy

PURPOSE

We studied the role of open surgery versus percutaneous nephrolithotomy (PCNL) in the treatment of complete staghorn stones in a prospective randomized manner.

MATERIALS AND METHODS

A total of 79 patients with 88 complete staghorn stones, defined as filling the entire collecting system or at least 80% of it, were prospectively randomized for PCNL (43) or open surgery (45). Intraoperative and postoperative morbidity, operative time, hospital stay, and stone clearance at discharge home and followup were compared for both methods. Patients with significant residuals in both groups were subjected to extracorporeal shock wave lithotripsy (Dornier Medical Systems, Inc., Marietta, Georgia) on an outpatient basis. Followup was completed for all cases with a mean duration +/- SD of 4.9 +/- 2.5 months (range 3 to 14). Renal function was evaluated by Tc-mercaptoacetyltriglycine renogram before and after treatment in both groups.

RESULTS

Intraoperative complications in terms of bleeding requiring blood transfusion, and pleural, vascular or ureteral injuries were recorded in 7 patients (16.3%) in the PCNL and 17 (37.8%) in the open surgery groups, a difference of significant value (p <0.05). Major postoperative complications including massive hematuria requiring blood transfusion, septicemia, urinary leakage and wound infection were observed in 8 patients (18.6%) in the PCNL group and in 14 (31.1%) in the open surgery group, a difference of no significant value. PCNL was associated with shorter operative time (127 +/- 30 vs 204 +/- 31 minutes, p <0.001), shorter hospital stay (6.4 +/- 4.2 vs 10 +/- 4.2 days, p <0.001) and earlier return to work (2.5 +/- 0.8 vs 4.1 +/- 1 weeks, p <0.001). On the other hand both treatment groups were comparable in regard to stone-free rates at discharge home (49% vs 66%) and at followup (74% vs 82%). At followup renal function improved or remained stable in 91% and 86.7% in the PCNL and open surgery groups, respectively.

CONCLUSIONS

PCNL is a valuable treatment option for complete staghorn stones with a stone-free rate approaching that of open surgery. Moreover, it has the advantages of lower morbidity, shorter operative time, shorter hospital stay and earlier return to work.

Nonsurgical management of infection-related renal calculi

Struvite calculi can be a debilitating affliction for which the cure is mainly surgical. If left untreated, infection-related calculi can cause failure to thrive, anemia, chronic renal insufficiency, renal failure and death. There has been much research aimed at non-surgical intervention and prevention of these calculi especially in this "non-invasive" era. The historic and current non-surgical treatment modalities of struvite calculi are discussed.

Complete staghorn calculi: random prospective comparison between extracorporeal shock wave lithotripsy monotherapy and combined with percutaneous nephrostolithotomy

PURPOSE

We determined the preferred treatment of staghorn calculi.

MATERIALS AND METHODS

Between January 1992 and December 1994 we performed a prospective, randomized, single center study involving 50 kidneys with complete staghorn calculi: 27 renal units were treated with extracorporeal shock wave lithotripsy (ESWL) monotherapy (group 1) and 23 were treated with combined (initial) percutaneous nephrostolithotomy with ESWL (group 2). The 2 treatment groups were compared regarding stone size, grade of collecting system dilatation and urine culture at presentation. The number of treatment sessions, narcotic doses, renal colic episodes, septic complications, unplanned ancillary procedures, length of hospitalization, total treatment duration and stone-free rate at 6 months were recorded and compared.

RESULTS

At the conclusion of therapy the stone-free rate was significantly greater in group 2 than in group 1 (74 versus 22%, respectively, p = 0.0005). The complication rate was significantly greater in group 1, with 15 septic complications (fever greater than 38.5C for longer than 3 days) in 10 patients compared to only 2 episodes in group 2 (p = 0.007). The unplanned ancillary procedure rate was significantly greater in group 1 (8 procedures in 7 patients versus 1 procedure in group 2, p = 0.03). The overall treatment length was significantly shorter in group 2 (1 versus 6 months, p = 0.0006). There was no significant difference in the number of procedures performed with anesthesia or in the number of hospitalization days between the 2 treatment groups.

CONCLUSIONS

Combined percutaneous nephrostolithotomy and ESWL should be recommended as the first line treatment choice for most patients with staghorn stones.

Staghorn calculi

Struvite staghorn calculi are infected stones that represent a real threat to the kidney and to the patient and are an indication for active treatment in most individuals. SWL, PL, combined PL and SWI, and open surgery are all viable treatment options for these patients. Most patients should be treated with combined therapy, reserving SWL for small-volume stones and open surgery for difficult situations that do not lend themselves to combined treatment.

Outcome of extracorporeal shockwave lithotripsy monotherapy for large renal calculi: effect of stone and collecting system surface areas and cost-effectiveness of treatment

The treatment options for large renal calculi are controversial. We report on our experience with 65 treatments of renal calculi > 3 cm using extracorporeal shockwave lithotripsy (SWL) monotherapy. We stratified our results according to stone and collecting system surface areas (measured by computer image analyses), stone location, and stone type. The overall success rate of SWL monotherapy was 27% at 3 months. The best stone-free rate (60%) was obtained for stones < 500 mm2 and located primarily within the renal pelvis. The stone-free rate for stones with surface areas > 1000 mm2 was only 8%. None of the cystine stones was treated successfully, whereas 80% of patients with uric acid stones became stone free. We estimated an average cost of $67,048 to render a patient with a large renal calculus stone free using SWL monotherapy. We recommend that other treatment options, such as percutaneous nephrolithotomy, be considered as first-line therapy for large renal calculi.

Estimated blood loss and transfusion rates associated with percutaneous nephrolithotomy

We analyzed retrospectively 127 percutaneous nephrolithotomies performed on 96 patients between 1986 and 1989 to estimate the average total blood loss from the procedure. Blood transfusions and a postoperative decrease in hemoglobin level were combined to estimate total blood loss. The average blood loss for uncomplicated 1-stage single puncture percutaneous nephrolithotomy was 2.8 gm./dl. hemoglobin. Factors potentially influencing blood loss were identified. Multiple punctures and/or renal pelvic perforation was associated with a 2-fold greater blood loss. Half of the expected blood loss occurred in patients with a preexisting nephrostomy tract. Calculus morphology, location, composition and length did not affect total blood loss, nor did the number of fragments or stone-containing calices. Other factors, such as puncture site, type of fascial dilation, hypertension, renal insufficiency, infection, previous open renal surgery or previous extracorporeal shock wave lithotripsy, also did not affect total estimated blood loss. During the study years the blood transfusion rate was 23% in all patients and 14% in those with a single puncture uncomplicated by renal pelvic perforation and without a mature nephrostomy tract. The only statistically significant risk factors influencing the likelihood of a blood transfusion were preoperative anemia and total blood loss. Although our current transfusion rate associated with percutaneous nephrolithotomy (4% in nonanemic patients from 1989 to 1992) is much lower, patients must be made aware of the likelihood of blood transfusion, and urologists should recognize the risk factors for blood loss and transfusion.

Experience with extracorporeal shock-wave lithotripsy (ESWL) for urinary calculi

Over a 36-month period 2800 patients were subjected to extracorporeal shock-wave lithotripsy (ESWL). A total of 5154 procedures were done. Best results were seen with renal pelvic calculi (not larger than 2.5 cm in diameter). Fragments of crushed lower calyceal calculi proved the most difficult to eliminate. As ureteral stone localization approached the bladder, the ESWL results were poorer. Post-ESWL complications were proportional to the stone mass; the higher the mass the more numerous the complications tended to be. Besides erythrocyturia and gross haematuria renal colic was the most frequent complication in almost 60% of the patients. Less prevalent were impacted ureteral stones, subcapsular haematoma and fever. At our institution, thanks to the ESWL method about 80% of the patients were spared surgery.

Percutaneous nephrolithotomy for large and staghorn calculi

The treatment of choice for a stone load of up to 3 cm is indubitably extracorporeal shock wave lithotripsy (SWL). However, for larger stones, and particularly staghorn calculi, the choice is not that clearcut. Our experience with percutaneous nephrolithotomy (PCNL) for a stone load larger than 3 cm in 878 renal units over 9 years has left us convinced that a well-planned and determined effort at percutaneous clearance is the best option for these difficult cases. Our overall complete clearance rate in this group is 93% and ranges from 98.5% for solitary calculi to 71% for complete staghorn calculi. These results are comparable to those reported by other workers with percutaneous monotherapy and are superior to those achieved by SWL monotherapy. The complication rate was acceptably low at 4%. We conclude that the expeditiousness and the better stone-free rates of PCNL justify the slightly higher morbidity that it entails when compared with SWL monotherapy. We also prefer to aim for total clearance percutaneously, leaving for SWL only those stones that defy our best efforts.

Stone surface area determination techniques: a unifying concept of staghorn stone burden assessment

The use of stone surface area measurements obtained from standard radiographs provides a more accurate and reproducible assessment of stone burden when reporting results and treatment recommendations for staghorn calculi. Techniques for determining stone surface area include use of graph paper, planimeter or computerized image analysis. The use of graph paper is inefficient while planimeters suffer from significant variation for areas less than 500 mm.2 (more than 5%). Computer image analysis is accurate, rapid and easiest to perform. Software programs compatible with microcomputers are readily available making assessment of stone surface area practical and inexpensive. Stone surface area showed close correlation to stone volume as measured by 3-dimensional computerized tomography (correlation coefficient 0.84, p = 0.005). Stone surface area determination enables more accurate reporting of treatment results and, thus, recommendations based upon stone burden. Comparison of data between institutions becomes more meaningful if stone surface area is used. Stone surface area also provides a useful basis to study and compare trends of treatment within a single institution.

Percutaneous nephrolithotripsy for renal stones in over 1000 patients

Over a period of 5 consecutive years, 1039 renal units were treated by percutaneous nephrolithotripsy for stone disease of the kidney. The success rate was 93.7%. Residual stones remained in 4.2% of patients and in 2.1% we failed to remove the stones. The complication rate was 17.8%. Complications were treated conservatively in most cases but nephrectomy was required on one occasion to control severe bleeding. The average hospital stay was 6.9 days. Follow-up of 339 renal units (333 patients), for a minimum of 60 months, revealed minor late sequelae such as pelviureteric junction obstruction in 1 patient (0.3%) and post-catheterisation strictures of the anterior urethra in 4 (1.2%). Stone recurrence was observed in 9.1% of patients. Percutaneous nephrolithotripsy is an effective, safe treatment for renal stones with minimal late sequelae and is still required even in the era of extracorporeal shock wave lithotripsy.

Staghorn calculi: analysis of treatment results between initial percutaneous nephrostolithotomy and extracorporeal shock wave lithotripsy monotherapy with reference to surface area

Treatment recommendations and results reported for the management of staghorn calculi are highly variable. In an attempt to provide a more objective means to compare treatment results for staghorn renal calculi, stone burden as measured by stone surface area was used. Stone surface area was determined by computer analysis. A total of 380 cases of staghorn calculi treated at the same institution was evaluated. Treatment consisted of initial percutaneous nephrostolithotomy with or without extracorporeal shock wave lithotripsy (ESWL*) in 298 cases and ESWL monotherapy in 82. When considered as a group, the overall stone-free rate for initial percutaneous nephrostolithotomy (mean surface area 1,378.3 mm.2) was 84.2% compared to 51.2% (p less than 0.0001) for ESWL monotherapy (mean surface area 693.4 mm.2). For staghorn calculi smaller than 500 mm.2 a stone-free rate of 94.4% was achieved in the percutaneous nephrostolithotomy with or without ESWL group compared to 63.2% for ESWL monotherapy (p = 0.0214). For calculi of 501 to 1,000 mm.2 the stone-free rates were 86% and 45.7%, respectively (p less than 0.0001). When stone surface area exceeded 1,000 mm.2 the stone-free rate for percutaneous nephrostolithotomy with or without ESWL was 82.4% but it was only 22.2% for ESWL monotherapy (p = 0.0002). Overall, when adjusted for stone surface area the odds of being stone-free were more than 8 times higher for initial percutaneous nephrostolithotomy versus ESWL monotherapy (odds ratio = 8.36, p less than 0.0001). While percutaneous nephrostolithotomy with or without ESWL appears to be the procedure of choice for most staghorn stones, ESWL monotherapy may have a role for some stones smaller than 500 mm.2. In 12 such cases associated with a nondilated renal collecting system (mean surface area 380.5 mm.2) a stone-free rate of 91.7% was achieved. The number of procedures required to complete therapy was higher in the initial percutaneous nephrostolithotomy group (2.8 versus 2.1, p less than 0.0001). Although complications were more common in the ESWL monotherapy group (manifested as obstruction in 30.5%), bleeding requiring blood transfusion was more frequent in the initial percutaneous nephrostolithotomy group (9.4%).

Staghorn renal calculi: Personal experience with PCN

We report the results on 47 patients treated for staghorn renal calculi (partial and complete) by PCN-monotherapy and PCN-debulking. According to Rocco's classification the renal stones were 34 C4 and 13 C5. The PCN-monotherapy was used for 34 C4 and 6 C5, and showed itself to be resolutive in 83.4%. We resorted to the PCN-debulking in 7 cases, all C5: subsequent treatment with Extracorporeal Shock Wave Lithotripsy (ESWL) was performed or planned in other Centres. We emphasize the feasibility of PCN in staghorn renal calculi for the low incidence of major complications and for sometimes reducing the wait, both before and after treatment of complex renal lithiasis.