Original Research

JOURNAL OF ENDOUROLOGY Volume XX, Number XX, XXXX 2014 ª Mary Ann Liebert, Inc. Pp. ---–--DOI: 10.1089/end.2014.0584

Ambulatory Percutaneous Nephrolithotomy: What Is the Rate of Readmission? Darren Beiko, MD, MBA, FRCSC,1 Mohamed A. Elkoushy, MD, MSc, PhD,2,3 Andrea Kokorovic, MD, MSc,1 Gregory Roberts, MD, FRCSC,1 Sylvia Robb, RN,1 and Sero Andonian, MD, MSc, FRCSC, FACS 2

Abstract

Background and Purpose: Tubeless percutaneous nephrolithotomy (PCNL) has gained popularity in an attempt to decrease morbidity and accelerate discharge. Recently, ambulatory tubeless PCNL has been reported. There are no data, however, regarding readmission rates of patients who had ambulatory PCNL. Therefore, the aim of this study was to assess rates of emergency department (ED) visits and readmissions postambulatory PCNL. Patients and Methods: A retrospective chart review of all ambulatory PCNL cases at two institutions between March 2007 and December 2013 was performed. Preoperative, intraoperative, and postoperative data were collected including the amount of narcotics used, length of hospital stay, postoperative complications, returns to the ED, and readmissions. Results: Fifty patients underwent ambulatory PCNL, including two bilateral cases, making up a total of 52 renal units. All patients were discharged home on the same day with a mean hospital stay of 208.32 – 73.43 minutes. The mean narcotic requirement was 41.13 – 46.76 mg of oral morphine equivalents. Six patients (12%) returned to the ED, all within 7 days. Four of these 6 patients were discharged; three with stent colic and one with wound cellulitis. Only two (4%) patients were readmitted—one with multiresistant Escherichia coli and one with uncomplicated stent colic. Overall stone-free rate was 90.4%. There were no major complications, while low grade (I-II) Clavien complications developed in 9 (18%) patients. Conclusion: Ambulatory PCNL is safe in highly selected patients with a stone-free rate of 90% and readmission rate of 4%. Prospective studies comparing standard PCNL with ambulatory PCNL are warranted.

have been admitted overnight to the hospital, regardless of whether the conventional or tubeless approach is used. Recently, ambulatory tubeless PCNL has been reported, whereby patients meeting strict criteria were safely discharged home on the same day as the procedure.9–11 There are no data, however, regarding readmission rates of patients who had ambulatory PCNL. Therefore, the aim of this study was to assess rates of emergency department (ED) visits and readmissions postambulatory PCNL.

Introduction

S

ince its conception in 1976, percutaneous nephrolithotomy (PCNL) has become the gold standard procedure for the treatment of patients with large renal calculi.1 The original method involved placement of a nephrostomy tube postoperatively to secure the tract, allow drainage of urine, and impede hemorrhage.1 Unfortunately, indwelling nephrostomy tubes have been known to cause significant morbidity in the form of postoperative discomfort and increased analgesic requirements.2 Consequently, modifications to the original procedure have been developed in an attempt to decrease morbidity. The most widely used of these is the tubeless PCNL variant, whereby a ureteral stent is left in place instead of a nephrostomy tube.3 This approach has been successful in decreasing postoperative discomfort and length of hospital admission.2,4–8 Traditionally, patients undergoing PCNL 1 2 3

Patients and Methods

A retrospective review of prospectively collected data for patients undergoing ambulatory PCNL in two tertiary care centers was performed. All procedures were performed by single surgeons, DB and SA, at Kingston General Hospital (KGH) of Queen’s University (Kingston, Ontario, Canada) and Royal Victoria Hospital (RVH) of McGill University Health Centre (Montreal, Quebec, Canada), respectively.

Department of Urology, Queen’s University, Kingston, Canada. Division of Urology, Department of Surgery, McGill University, Montreal, Canada. Department of Urology, Suez Canal University, Ismailia, Egypt.

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2 Selection criteria

Strict selection criteria were based on preoperative, intraoperative, and postoperative factors. The initial strict criteria have been published previously and were as described in the following paragraph. Preoperatively, patients should not have significant comorbidities such as American Society of Anesthesiologists (ASA) score ‡ 3, body mass index (BMI) > 35 kg/m2, solitary or transplanted kidney, active cardiac disease, renal insufficiency, or encrusted stents. In addition, patients should have adequate family support that is agreeable to same-day discharge planning. Patients who came from long distances were not candidates for the ambulatory PCNL approach and were offered standard PCNL. Intraoperatively, patients should not need > 3 punctures to obtain access, multiple tracts, or have residual stones necessitating second-look nephroscopy. Moreover, patients should not have intraoperative complications such as pelvicaliceal perforation or excessive bleeding especially during removal of the access sheath. Postoperatively, patients should be hemodynamically stable, have hematocrit > 30%, adequate pain control, and normal chest radiography. Furthermore, patients should be able to ambulate and have a successful trial of void unless they are discharged home over the weekend with an indwelling Foley catheter.9,10 As both centers gained experience with ambulatory PCNL, these stringent criteria were loosened to include more complex cases. Four patients had preoperative nephrostomy tubes and did not need new renal accesses. Flexible cystoscopy with retrograde ureterourography, Foley catheter placement, and prone PCNL using 30F Amplatz sheaths were performed under general anesthesia as described previously.8,9,11 With the exception of two totally tubeless patients and another patient with caliceal diverticulum who had an 8.5F nephrostomy tube, all patients had 6F indwelling ureteral stents inserted at the end of the procedure once stone-free status was confirmed and hemorrhage was ruled out.9,10 The attending surgeon, in consultation with the patient/ family, anesthesiologist, and postanesthesia care unit (PACU) nursing team, made the decision to discharge patients home from the PACU. All patients at KGH and female patients at RVH had their trial of voids in the PACU before discharge. Male patients at RVH were sent home with Foley catheters over the weekend to have their trial of void on Monday because their procedures were on Fridays. At KGH, indwelling double-pigtail ureteral stents were removed 2 to 8 weeks postoperatively, while at RVH they were removed 1 to 2 weeks postoperatively. All patients and their families were given appropriate instructions to return to the ED should postoperative complications of nausea, vomiting, fever, or significant gross hematuria occur. Follow-up imaging 1 to 8 weeks postoperatively included kidneys, ureters, and bladder (KUB) plain radiography – renal ultrasonography or CT scan (for radiolucent or faintly opaque stones). Patient characteristics collected included age, sex, BMI, ASA classification, and medical history including history of previous urolithiasis. Preoperative data collected included imaging studies (date, type, and findings), stone characteristics (side, number, location, and size [maximum diameter of largest stone in renal unit]), renal anatomy, and serum creatinine, hemoglobin, and hematocrit levels. Intraoperative

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data included retrograde urography findings, procedures completed, puncture sites and numbers, nephroscopy findings, intracorporeal lithotripsy modality, basket use, method of renal drainage, incidence of intraoperative complications (hemorrhage, perforation, residual stone fragments), and length of operation. Postoperative data included postoperative hemoglobin, hematocrit, chest radiography, postoperative narcotic doses, length of stay, return visits to the ED, complications, stonefree status, and stone composition. Stone-free status was defined as either complete stone clearance or clinically insignificant residual fragments < 3 mm at 1 to 8 week followup CT/KUB studies. In addition, medical records at both hospitals were reviewed to capture ED visits and readmissions. Statistical analysis

Data were analyzed using the commercially available Statistical Package for Social Sciences for windows, version 20 (IBMª SPSS, Armonk, New York). Descriptive statistics were reported in terms of number and percentages or means and standard deviations for categorical and continuous variables, respectively. Postoperative complications were reported using the modified Clavien-Dindo classification system.12,13 Paired t test was used to compare preoperative and postoperative continuous variables where a two-tailed P < 0.05 was accepted for statistically significant differences. Results

Fifty patients underwent ambulatory PCNL, including two concomitant bilateral procedures, involving a total of 52 renal units between March 2007 and November 2013. Seventeen patients were treated at RVH and 33 patients (35 renal units) were treated at KGH. Twenty-one (42%) patients had multiple stones in the treated kidney. Twenty-three (44%) of the 52 renal units were complex cases including 12 (23.1%) renal units with complex renal anatomy and 11 (21.1%) renal units with staghorn calculi. Two patients with bilateral staghorn calculi underwent bilateral PCNL on an outpatient basis. Mean stone size was 19.6 mm (range 7–60) (Table 1). Mean operative time, including cystoscopy, was 90.91 – 40.80 minutes. Most (56%) patients had lower pole access (Table 2). Thirty patients (32 renal units) needed intracorporeal lithotripsy while a stone grasper or basket was used in the remaining 20 patients to remove the stones without fragmentation. There were no significant intraoperative medical, anesthetic, or surgical complications, including major hemorrhage, perforation, or failed percutaneous access. Compared with the preoperative level, postoperative serum creatinine level was essentially stable (86.2 – 25.5 lmol/L vs 85.1 – 27.2 lmol/L; P = 0.67). Although there was a significant decrease in the postoperative hemoglobin level (136.3 – 18.5 g/L vs 127.2 – 20.4 g/L; P = 0.001), this was not clinically significant. Mean postoperative narcotic equivalents were 41.13 – 46.76 mg of oral morphine equivalents, and the mean hospital stay was 208.32 – 73.43 minutes, or 3 hours and 29 minutes. Postoperative complications are shown in Table 3 according to the modified Clavien-Dindo classification system.13,14 Forty-one (82%) patients had no postoperative complications. Six patients sustained Clavien grade I postoperative

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Table 1. Baseline Patient and Stone Characteristics of Patients Undergoing Ambulatory Percutaneous Nephrolithotomy Patient Characteristics

No (%) / means (range)

Mean age (years) Sex: Female: Male Mean BMI (kg/m2) ASA class ASA class I ASA class II ASA class III History of stones Anatomic/renal factors Medullary nephrocalcinosis Ureteropelvic junction obstruction Caliceal diverticula Bifid renal pelvis Extrarenal pelvis Ileal conduit urinary diversion Indiana pouch urinary diversion Total complex anatomy Stone factors Mean stone size (mm) Left-sided stones Multiple stones Staghorn calculi Patients Renal units

55.8 (21–80) 24 (48):26 (52) 29.3 (21–52) 9 33 8 35

(18%) (66%) (16%) (70%)

3 2 2 2 1 1 1 12

(6%) (4%) (4%) (4%) (2%) (2%) (2%) (24%)

19.6 (7–60) 29 (55.8) 23 (44%) 9 (18%) 11 (21%)

Data were presented in terms of number (%) or mean (range), whichever appropriate. ASA = American Society of Anesthesiologists.

complications, and three patients had Clavien grade II complications, for a total of 9 (18%) minor complications (Table 3). There were no Clavien grade III or greater complications, indicating no major complications or deaths. Six (12%) patients returned to the ED within 7 days including four patients who were discharged—three with stent colic and one with wound cellulitis. Only two (4%) patients were readmitted—one with multiresistant Escherichia coli and one with uncomplicated stent colic. Another patient was discovered to have deep vein thrombosis on a visit for cystoscopy on postoperative day 7 and was treated with low molecular weight heparin on an outpatient basis without any hemorrhagic complications. Of the four patients with stent colic, one was readmitted for pain control. The other admission was for intravenous gentamicin for multiresistant E. coli urinary tract infection (UTI). Therefore, there were two (4%) readmissions (Fig 1). Stent migration and spontaneous expulsion before follow-up appointment occurred in one patient with ileal conduit without any clinical significance. In addition, wound cellulitis, which developed in one patient, was treated with oral cephalexin on an outpatient basis. Another patient’s follow-up CT scan at 5 weeks showed periureteral inflammation with thrombosis of a 7.5 cm segment of the adjacent right ovarian vein. Her symptoms resolved after removal of the indwelling ureteral stent 2 days later, and the imaging findings of ovarian vein thrombosis remained subclinical and resolved on follow-up CT scan. Overall, 92% (46/50) of patients were stone free and 90.4% (47/52) of renal units were stone free, including 97.6% (40/41) of nonstaghorn calculi renal units, while the stone-

Table 2. Intraoperative Parameters for Patients Undergoing Ambulatory Percutaneous Nephrolithotomy Intraoperative variables

No. (%)

Percutaneous access Primary Upper calix Middle calix Lower calix Secondary Middle calix Lower calix Intracorporeal lithotripsy None (intact stone extraction) Ultrasonic Ballistic Laser Electrohydraulic Combination ultrasonic + ballistic Ballistic + laser Concomitant procedures Endopyelotomy Caliceal diverticulotomy Antegrade ureteroscopy Cystolitholapaxy Renal drainage Antegrade ureteral stent Retrograde ureteral stent 8.5F Cope loop nephrostomy No stent or nephrostomy (totally tubeless)

20 (38%) 3 (6%) 29 (56%) 1 (2%) 1 (2%) 20 21 5 3 1 1 1

(38%) (40%) (10%) (6%) (2%) (2%) (2%)

2 2 1 1

(4%) (4%) (2%) (2%)

41 8 1 2

(79%) (15%) (2%) (4%)

free rate for staghorn calculi was 64%. Stone analysis revealed 28 mixed stones and 24 pure stones. Of the 24 pure stones, there were 18 calcium oxalate, 3 struvite, and 3 uric acid stones. The major components of the 28 mixed stones were calcium oxalate in 13, struvite in 8, calcium phosphate in 4, uric acid in 1, cystine in 1, and matrix in another stone. Discussion

Traditionally, patients undergoing PCNL, conventional or tubeless, are admitted overnight. Although ambulatory

Table 3. Postoperative Complications for Patients Undergoing Ambulatory Percutaneous Nephrolithotomy According to the Clavien Classification System Clavien grade Grade I Grade II

Grades III–V

Complication Stent colic* Extruded ureteral stent Ovarian vein thrombosis DVT necessitating LMWH Multiresistant E. coli UTI* Wound cellulitis*

Patients No (%) 4 1 1 1

(8%) (2%) (2%) (2%)

Total 6 (12%) 3 (6%)

1 (2%) 1 (2%) 0 (0%)

0 (0%)

*emergency department visit. DVY = deep vein thrombosis; LMWH = low molecular weight heparin; E. coli = Escherichia coli; UTI = urinary tract infection.

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FIG. 1. A schematic representation of readmissions postambulatory percutaneous nephrolithotomy. PCNL has been reported in highly selected patients meeting strict criteria, ED visits and hospital readmission rates had not been examined previously.9–11,14 In this study, 92% (46/50) of patients were stone free and 90.4% (47/52) of renal units were stone free. The stone-free rates are higher than those reported in the Clinical Research Office of the Endourological Society (CROES) study, which reported a 30day stone-free rate of 75.7%.15 The high stone-free rates found suggest that ambulatory PCNL is effective. Although complex PCNL cases were not expected to be performed at the outset of the study, in the end, there were 12 patients with complex renal anatomy and 9 patients with staghorn calculi. Moreover, 82% had no complications, and the rate of minor complications (Clavien grades I and II) was 18%. This is similar to the CROES prospective global study in which there were no complications in 79.5% and 16.4% had Clavien grades I and II complications.15 Unlike the CROES study, however, in which there were 4.13% major complications (Clavien III–V), there were no major complications in the present study. This is probably related to the strict selection criteria that were used to highly select patients for the ambulatory approach.9,10 There were six (12%) patients who returned to the ED and two (4%) patients who were readmitted to hospital. Gnessin and associates16 examined readmissions post-PCNL. They found that patients without a postoperative CT scan had a readmission rate of 5.33%. This is similar to the 4% readmission rate found in the present study, although patients were readmitted for stent colic and multiresistant UTI in this study while patients were readmitted for perinephric hematomas and ureteral clot obstruction in the other study. Another abstract found similar readmission rates of ambulatory laparoscopic cholecystectomy and ambulatory PCNL with readmission rates of 2.2% and 3.27%, respectively.11 This is similar to the 4% readmission rate found in the present study. The stone-free rate for staghorn calculi is 64%, which is similar to the staghorn stone-free rates achieved in the CROES global PCNL study (57%).17 Therefore, once experience was gained in performing ambulatory PCNL in simple lower pole caliceal stones, more complex cases were successfully tackled. In fact, Abbott and colleagues11 compared their ambulatory PCNL series of 61 patients with laparoscopic cholecystectomy data using the Clavien classification system and found similar complication rates and readmission rates when managing stones less than 20 mm. The retrospective nature of the current study and its small sample size represent its main limitations. Moreover, two different centers were involved, leading to slight variations in

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surgical technique. Consequently, the results may not necessarily be assumed to be reproducible in other patient populations. Furthermore, our stone-free rate parameters differed from those used in the CROES Global PCNL study.15 This might be because of the differences in follow-up times and the definitions of stone-free status. Other limitations include lack of cost analysis and assessment of patient satisfaction. Given the low readmission rate of 4%, however, it is expected that ambulatory PCNL is associated with significant savings and enhanced patient satisfaction when compared with standard tubeless PCNL. In addition, a previous study on cost analysis demonstrated 30% cost savings with the ambulatory approach when compared with standard PCNL.11 Notwithstanding these limitations, the current cohort represents the largest multicenter study for ambulatory PCNL. Conclusions

Ambulatory PCNL is safe in highly selected patients with a stone-free rate of 90% and readmission rate of 4%. Further prospective studies comparing readmissions after standard and ambulatory PCNL are warranted. Acknowledgments

This work was supported in part by the Northeastern AUA Young Investigator Award and Montreal General Hospital Foundation Award to Sero Andonian and the Academic Health Sciences Centre (AHSC)-Alternate Funding Payment (AFP) Innovation Fund Research Grant to Darren Beiko. Disclosure Statement

No competing financial interests exist. References

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10. Beiko D, Lee L. Outpatient tubeless percutaneous nephrolithotomy: The initial case series. Can Urol Assoc J 2010;4:E86–E90. 11. Abbott JE, Deem SG, Simpson EE, Davalos JG. Outpatient percutaneous nephrolithotomy: A comparative analysis with laparoscopic cholecystectomy. J Endourol 2012; 26(suppl):A168–A169. 12. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: A new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004;240:205–213. 13. de la Rosette JJ, Opondo D, Daels FP, et al. Categorisation of complications and validation of the Clavien score for percutaneous nephrolithotomy. Eur Urol 2012;62:246–255. 14. Preminger GM, Clayman RV, Curry T, et al. Outpatient percutaneous nephrostolithotomy. J Urol 1986;136:355– 357. 15. de la Rosette J, Assimos D, Desai M, et al. The Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study: Indications, complications, and outcomes in 5803 patients. J Endourol 2011; 25:11–17. 16. Gnessin E, Mandeville JA, Handa SE, Lingeman JE. The utility of noncontrast computed tomography in the prompt diagnosis of postoperative complications after percutaneous nephrolithotomy. J Endourol 2012;26:347–350. 17. Desai M, De Lisa A, Turna B, et al. The clinical research office of the endourological society percutaneous ne-

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phrolithotomy global study: Staghorn versus nonstaghorn stones. J Endourol 2011;25:1263–1268.

Address correspondence to: Sero Andonian, MD, MSc, FRCSC, FACS Division of Urology Department of Surgery McGill University 687 Pine Avenue West, Suite S6.92 Montreal, Quebec Canada H3A 1A1 E-mail: [email protected] Abbreviations Used ASA ¼ American Society of Anesthesiologists BMI ¼ body mass index CROES ¼ Clinical Research Office of the Endourological Society CT ¼ computed tomography ED ¼ emergency department KGH ¼ Kingston General Hospital PACU ¼ postanesthetic care unit PCNL ¼ percutaneous nephrolithotomy RVH ¼ Royal Victoria Hospital UTI ¼ urinary tract infection

Ambulatory percutaneous nephrolithotomy: what is the rate of readmission?

Tubeless percutaneous nephrolithotomy (PCNL) has gained popularity in an attempt to decrease morbidity and accelerate discharge. Recently, ambulatory ...
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