1 FLEXIBLE URETEROSCOPY AND LASER LITHOTRIPSY VERSUS ESWL IN MANAGEMENT OF LOWER CALYCEAL RENAL STONES THESIS SUBMITTED FOR THE PARTIAL FULFILLMENT OF THE MD DEGREE IN UROLOGY BY AHMED SALEM METWALLY M.B., B. Ch., M. Sc. Assistant lecturer of Urology Faculty of medicine Cairo University SUPERVISED BY Prof. Dr. Mongy Abdel Kader Fathy Professor of Urology Faculty of medicine Cairo University Prof. Dr. Omar M. Abdel Razzak Professor of Urology Faculty of medicine Cairo University Dr. Ismail Rady Saad Assistant professor of Urology Faculty of medicine Cairo University Faculty of medicine Cairo University 2012
2 Abstract INTRODUCTION AND OBJECTIVES: Urolithiasis, especially lower calyceal (LC) stones, is a common medical problem. Its prevalence is around 2% to 3 % in general population. With advances of endourologic and laser technology, flexible ureterorenoscopy (FURS) and laser lithotripsy (LL) are considered the second line therapy in ESWL-resistant LC stones. This study aimed to assess safety, efficacy and outcome of FURS and holmium: YAG LL comparing its results to ESWL in LC stones. METHODS: A prospective randomized study was done from May 2010 to May It included patients with radiopaque unilateral, single or multiple, LC 20mm. Patients were divided into 2 groups. In Group I, patients underwent FURS and LL using 365 µm laser fibers. In Group II, patients underwent ESWL. Patients were followed for 3 months by KUB to assess stone-free status defined as no fragments or fragment 3mm. In each group, multiple parameters (age, sex, stone size and number, and LC anatomy) were examined to assess impact on stone-free status. Additionally stone-free status and complications were compared in both groups. RESULTS: 60 patients were included in the study. In Group I (N=30), mean age was 44.2 years and mean stone size was 11.5mm. 26 patients (86.7%) had single stone and 4 patients (13.3%) had multiple stones. Stone free status was achieved in 29 patients (96.7%). Complication rate was 16.7%. Age, sex, stone size and number, and LC anatomy did not correlate with stone free status in Group I. In Group II (N=30), mean age was 35.5 years and mean stone size was 11.3mm. 28 patients (93.3%) had single stone and 2 patients (6.7%) had multiple stones. Stone-free status was achieved in 17 patients (56.7%). Complication rate was 23.3%. Stone size (<10mm) only correlated with stone-free status in Group II. FURS and LL achieved significantly better stonefree rates compared to ESWL (96.7% vs 56.7%, p= 0.001), with no difference in complication rate between both groups (16.7% vs 23.3%, p= 0.5). CONCLUSION: Both FURS with LL and ESWL are considered safe in treating LC stones less than 20mm with minimal complication rates. However, FURS with LL achieved significantly better stone-free rates. Stone size could predict stone-free status in ESWL. Key Words: Anatomy of the kidney and ureter, Urolithiasis, Ureteroscopy, Extracorporeal shockwave lithotripsy, Laser Lithotripsy
3 ACKNOWLEDGEMENTS First of all I thank GOD, without his help this work would have never existed. I would like to express my sincere thanks and respect to Professor Dr. Mongy Abdel Kader, Professor of urology, Faculty of medicine, Cairo University, for his valuable brotherly help during this work. I also wish to express my extreme appreciation to Professor Dr. Omar Abdel Razzak, Professor of urology, Faculty of medicine, Cairo University for his guidance, encouragement, unlimited support, constructive criticism, and wise counseling throughout this work. I would also like to express my great appreciation to Dr. Ismail Rady Saad, Assistant Professor of urology, Faculty of medicine, Cairo University, who was very generous in time and effort and for his faithful supervision in the progress of this work. I would also like to express special thanks to Dr. Ashraf Emran, Assistant Professor of urology, Faculty of medicine, Cairo University, and Dr. Mahmud Abdel Hakim, Lecturer of urology, Faculty of medicine, Cairo University for their great effort and sharing in this work. Lastly I would like to thank my family for their care and support all over this work.
4 Contents Introduction and aim of work..1-3 Review of literature: - Chapter I: Anatomy of the kidney and ureter Chapter II: Urolithiasis Chapter III: Ureteroscopy Chapter IV: Extracorporeal shockwave lithotripsy Chapter V: Laser Lithotripsy Materials and Methods Results Discussion Conclusion 74 References Arabic summary.
5 List of Tables Table 1: X-ray characteristics of stones. Table 2: Stone composition. Table 3: High risk stone formers. Table 4: Radiation exposure of different imaging modalities. Table 5: Complications of ureteroscopy. Table 6: Patient, stone and lower calyceal criteria of both groups, and their statistical significance. Table 7: Operative Data of Group I. Table 8: Operative details of Group II. Table 9: Complications, Complication rate and stone free rate of both groups and their statistical significance. Table 10: Correlation between age, stone number, stone size, lower calyceal anatomy and success rate 3M after flexible URS. Table 11: Correlation between age, stone number, stone size, lower calyceal anatomy and success rate 3M after ESWL. Table 12: Correlation between IW and IL, IPA, and stone size in group II. Table 13: Logistic regression analysis for predictors of stone free rate at 3 months.
6 List of Figures Figure 1: Schematic drawing of a longitudinal section of the kidney depicts the intra-renal structures. Figure 2: Schematic drawing representing the possibilities of minor calyx arrangement. Figure 3: Schematic drawing indicates the essential elements of kidney collecting system. Figure 4: Tip design of a flexible ureteroscope demonstrating the ends of the optical system, light transmission bundle, and working channel. Figure 5: Demonstration of flexible ureterorenoscopy, primary active followed by secondary passive deflection Figure 6: Flexible ureteroscope deflections. Figure 7: Comparison between complication rate of flexible URS and ESWL. Figure 8: Stone free rate after flexible ureteroscopy and laser lithotripsy. Figure 9: Stone free rate after 3M in patients underwent ESWL. Figure 10: Comparison between clinical outcome after flexible URS and ESWL in lower calyceal stones.
7 List of Abbreviations µm: micrometer. µs: microsecond. AST: Aspartate transaminase. CI: Confidence interval. cm: Centimeter CPK: Creatine phosphokinase. CT: Computed tomography. ECG: Electrocardiogram. EHL: Electro-hydraulic lithotripsy. ESWL: Extracorporeal shockwave lithotripsy. Fr: French. FURS: Flexible ureteroscopy. HU: Hounsfield units. Hz: Hertz. IL: Infundibular length. IPA: Infundibulo-pelvic angle. IVP: Intravenous pyelography. IVU: Intravenous urography. IW: Infundibular width. J: Joule. KUB: Kidney, Ureter, and Bladder. Kv: Kilovolt. Laser: Light Amplification for Stimulated Emission of Radiation. LDH: Lactate dehydrogenase. LL: Laser lithotripsy.
8 LP: Lower pole. mm: millimeter. Mpa: Megapascal. N: Number NCCT: Non-contrast spiral CT. Nd: Neodymium. nm: nanometer. ns: Nanosecond. OR: Odds ratio. PNL: Percutaneous nephrolithotomy. PO: Postoperative. RTA: Renal tubular acidosis. SFR: Stone free rate. U/S: Ultrasonography. URS: Ureteroscopy. YAG: Yttrium Aluminium Garnet.
9 Introduction Introduction and Aim of work Ureteroscopy was first used in 1912 by Hampton, who accidentally entered a massively dilated ureter with a 12 Fr cystoscope in a child with posterior urethral valve (Young and McKay, 1929). Flexible ureteroscopy became popular after the development of small diameter ureteroscopes in early 1990s with passive and active deflection allowing access to the entire collecting system in up to 94% of the procedures (Grasso and Bagley, 1998). Its ability to access the collecting system, associated with the development of a safe, reliable, and flexible endoscopic lithotripsy source, combined with more efficient extraction instruments made the flexible ureteroscopic laser lithotripsy more attractive to effectively treat urinary stones with high success rates and low morbidity. Flexible, actively deflectable ureteroscopes range from 6.75 to 9 Fr in diameter at the tip, with a working channel ranging from 3.6 to 4Fr. Additionally, these ureteroscopes offer the distinct advantage of being able to reach the entire urinary system including the lower pole of the kidney. Typical endoscopes offer 120 to 170⁰ of deflection in one direction and 170 to 270⁰ in the other. However, the degree of deflection may be altered with instruments (such as laser fibers) in the working channel that increase the stiffness and resistance to deflection of the endoscope (Chew et al, 2007). One of the most important developments in the endoscopic approach to urolithiasis has been the holmium: YAG (Yttrium Aluminium Garnet) laser for intracorporeal lithotripsy. The holmium: YAG laser is now recognized to be the gold standard for ureteroscopic intracorporeal lithotripsy. This pulsed solid-state laser system operates at 1
10 Introduction and Aim of work a wavelength of 2100 nm, which is near the infrared portion of the electromagnetic spectrum and, therefore, invisible to the human eye. Energy from the holmium: YAG laser produces a photo-thermal effect resulting in vaporization of the stone and is strongly absorbed by water and travels no further than 0.5 to 1.0 mm in a liquid medium, so decreasing ureteral damage (Dushinski and Lingeman, 1998; Wollin and Denstedt, 1998). Stone-free rates are about 90% in several series (Grasso, 1996; Hosking and Bard, 1996; Devarajan et al, 1998; Yip et al, 1998; Sofer et al, 2002). Laser fibers are available in sizes 200, 365, 400, 550, and 1000 µm. Typically, 200 to 400 µm fibers are utilized during ureteroscopy (Chew et al, 2007). The management of upper tract stone disease has shifted from surgery to the modern concept of minimally invasive approaches. ESWL has revolutionized the treatment of upper tract stones and has become the most employed option for these types of stones as well (Graff et al, 1988). However, its success rates are far from satisfactory and may vary from 80% for those smaller than 1 cm, 64% for those from 1cm to 2 cm to 54% for stones greater than 2 cm (Vallancien et al, 1988; Logarakis et al, 2000; Cass, 1995; Psihrames et al, 1992; Lingeman et al, 1994). The limitations of ESWL, namely larger stones, severely obese patients, special crystalline stones and stones in calyceal cysts or diverticula, has allowed the increased popularity of ureteroscopic treatment of renal stones coupled with flexible ureteroscopes and advancement in laser lithotripsy(grasso and Bagley, 1998). The clearance rate of lower pole calyceal calculi has been uniformly low (59%) compared to that of calculi elsewhere (Lingeman et al, 1994). The dependent position of the inferior calyx, and its spatial anatomy and 2
11 Introduction and Aim of work relationship to the renal pelvis appear to be significant factors in retention of residual fragments and so will be a major problem with both ESWL and ureteroscopy (Sampaio and Aragao 1994). Elbahnasy et al (1998) measured radiographic anatomical features in a well defined manner to establish the significance of its influence on the clearance of inferior calyceal calculi following ESWL or ureteroscopy. Additionally, Ghoneim et al in 2005 tested the effect of the anatomy of lower pole on fragment clearance after ESWL. He found that lower pole anatomy has a significant impact on ESWL results. An infundibulo-pelvic angle not < 70 and an infundibular length of < 50 mm are preferable to achieve favorable outcome. So it is important to determine, verify and define how these factors influence successful fragmentation and clearance of calculi from the inferior calyces. Aim of study: To assess the safety, efficacy and outcome of the flexible ureteroscopy using holmium YAG laser lithotripsy and compare its results with that of ESWL in management of lower calyceal renal stones. 3
12 Anatomy Review of literature ANATOMY OF THE KIDNEY AND URETER Endoscopic Anatomy of Pelvicalyceal System: A full understanding of pelvicalyceal anatomy is necessary to perform reliable endourologic procedures as well as uroradiologic analysis. This was aided by advances in endourologic equipment. The renal parenchyma consists basically of two kinds of tissue, the cortical tissue and the medullary tissue. On a longitudinal section, the cortex forms the external layer of renal parenchyma. The cortical tissue comprises the glomeruli with proximal and distal convoluted tubules. The renal medulla is formed by several inverted cones, surrounded by a layer of cortical tissue on all sides (except at the apexes). In longitudinal sections, a cone assumes the shape of a pyramid, and the expression for the medullary tissue is renal pyramid; the apex of a pyramid is the renal papilla. The layers of cortical tissue between adjacent pyramids are named renal columns (cortical columns of Bertin) (Fig. 1). The renal pyramids comprise the loops of Henle and collecting ducts; these ducts join to form the papillary ducts (about 20) which open at the papillary surface (area cribrosa papillae renalis), draining urine into the collecting system (into the fornix of a minor calyx) (Sampaio, 1993). A minor calyx is defined as the calyx that is in immediate opposition to a papilla. The renal minor calyces drain the renal papillae and range in number from 5 to 14 (mean 8), with 70% of kidneys having 7 to 9 minor calyces (Sampaio and Mandarim-de-Lacerda, 1988). A minor calyx may be single (drains one papilla) or compound (drains two or three papillae). 4
13 Anatomy Review of literature The polar calyces often are compound, markedly in the superior pole (Fig. 2). The minor calyces may drain straight into an infundibulum or join to form major calyces, which subsequently will drain into an infundibulum (Fig. 3). Finally, the infundibula, which are considered the primary divisions of the pelvi-caliceal system, drain into the renal pelvis (Sampaio, 1993). The compound calyces of the poles of the kidney are oriented facing their respective poles. The simple calyces usually come in pairs, one facing anteriorly and one facing posteriorly. The upper pole calyceal system almost always contains at least one compound calyx, and in some cases this is the only calyx in the system. Drainage of the upper pole into the renal pelvis is by a single midline infundibulum in the majority of kidneys. The lower pole system often contains a compound calyx as well. The calyceal drainage from the lower pole is via a single infundibulum in about half of kidneys and through a series of paired anterior and posterior calyces in approximately half of kidneys. Compound calyces are rare in the middle calyceal system. They are typically arranged in a series of paired anterior and posterior calyces (Wolf, 2012). In about two thirds of the kidneys, there are two major calyceal systems, an upper system and a lower system, and the middle calyces drain into either or both systems. In the other third of kidneys, the middle calyceal system is distinct from the upper and lower systems, either coalescing into a middle major calyx before emptying into the renal pelvis or with drainage of the middle minor calyces directly into the renal pelvis through short infundibula (Wolf, 2012). 5
14 Anatomy Review of literature Figure 1: Schematic drawing of a longitudinal section of the kidney depicts the intrarenal structures. c = renal cortex; rc = renal column (cortical column of Bertin); rp = renal pyramid; p = renal papilla; mc = minor calyx; Mc = major calyx; P = renal pelvis (Sampaio, 1993). Calyceal anatomy of the lower pole and its possible impact on stone clearance were first described by Sampaio and Aragao (1992). The dependent position of the inferior calyx, and its spatial anatomy and relationship to the renal pelvis appear to be significant factors in retention of residual fragments and, therefore, poor results of stone clearance. 6
15 Anatomy Review of literature Figure 2: Schematic drawing representing the possibilities of minor calyx arrangement. A single minor calyx drains only one papilla and a compound minor calyx drains two or three papillae. p = renal papilla; pd = papillary ducts; ac = area cribosa; mc = minor calyx; Mc = major calyx; imc = infundibulum of a minor calyx (caliceal neck); i = infundibulum (Sampaio, 1993). They described the anatomy of the lower pole by use of polyester resin endocasts of the intra-renal collecting system obtained from adult cadavers. A lower pole with multiple infundibula might have poor drainage and consequently less possibility of eliminating stone fragments than would an inferior pole drained by a single infundibulum receiving fused calyces. Also, a small diameter of the lower pole infundibulum might affect the passage of stone fragments, where stone clearance is better in a shorter calyx with a wider infundibulum than a longer calyx with a narrower infundibulum (Sampaio and Aragao 1992, 1994). 7
16 Anatomy Review of literature Figure 3: Schematic drawing indicates the essential elements of kidney collecting system. cc = compound calyx; sc = single calyx; mc = minor calyx; Mc = major calyx; f = caliceal fornix; i = infundibulum; P = renal pelvis (Sampaio, 1993). 8
17 Anatomy Review of literature There is wide variability in lower calyceal infundibular width between different intravenous pyelography phases. The width is greatest on the compression film and smallest on the postvoid film, which suggests the use of standardized timing when infundibular width is measured from an intravenous pyelogram (Wolf, 2012). Elbahnasy et al in 1998 measured radiographic anatomical features of the lower calyx to detect the significance of its influence on the clearance of inferior calyceal calculi following ESWL or ureteroscopy. Stone clearance has been shown to be poorer for an acutely angled than an obtusely angled inferior calyx; in addition, the poor clearance of stone fragments from lower calyx following ESWL is also attributed to the gravity dependant position of the lower pole. An infundibulo-pelvic angle not < 70 and an infundibular length of < 50 mm is preferable to achieve favorable outcome (Ghoneim et al, 2005). The optimal approach for management of patients with lower pole stones continues to evolve. ESWL is a consideration for individuals with lower pole stones of 1cm in aggregate size, because there is a reasonable chance of achieving a stone-free state with minimal morbidity. Patients with lower pole stones of 2 cm are still best treated with percutaneous nephrolithotomy (PNL), because this offers them the best chance of being rendered stone free with one procedure. Much of the controversy regarding treatment of lower pole stones is limited to stones of 10 to 20 mm in diameter. PNL, ureteroscopy, and ESWL are all acceptable options. Stone composition and lower pole anatomy should be considered in recommending a treatment modality for these patients. Patients with an acute lower pole infundibulopelvic angle (with or without other unfavorable anatomic features), patients whose ESWL treatment has failed, and patients known to have stones resistant to ESWL 9
18 Anatomy Review of literature should be treated with PNL, or flexible ureteroscopy and laser lithotripsy (Matlaga and Lingeman, 2012). There are certain maneuvers that may affect ureteroscopic treatment of lower calyceal calculi as any device passing through the working channel of a flexible ureteroscope will affect the scope s deflectability thus preventing access to the lower pole. Recently, development of nitinol baskets and flexible grasping devices has less adverse effect than do laser fibers on scope deflectibilty and may be used to displace a lower pole stone to the renal pelvis to facilitate laser lithotripsy. Kourambas and colleagues (2000) found that the stone-free rate of patients who were treated with stone displacement before fragmentation was 90% compared with a stone-free rate of 83% for those patients who underwent in-situ fragmentation. Schuster and colleagues in 2002 similarly reported a 77% stone-free rate for patients with lower pole calculi smaller than 1 cm treated in situ versus an 89% stone-free rate for those treated with displacement first. For patients with calculi larger than 1 cm, 100% of those undergoing displacement first were treated successfully compared with 29% of those treated in situ. The ureteral access sheath also may improve stone free rate in ureteroscopic management of lower pole calculi. Portis and colleagues in 2006 found that in patients with intra-renal calculi between 5mm and 15mm, the stone free rate has reached 59%, detected by computed tomography (CT), in those where ureteral access sheath and stone displacement had been applied. 10
19 Anatomy Review of literature ANATOMY OF THE URETER: Endoscopic anatomy: The trigone is a raised, smooth triangular area with its apex at the bladder neck and its base formed by the interureteric ridge or Mercier's bar extending between the two ureteral orifices. It lies just inside the bladder neck and it is the most vascular part of the bladder. It is formed by an extension of the longitudinal muscle fibers of the ureters superimposed over the detrusor muscle. The normal nonrefluxing orifice may have the appearance of a volcano, a horseshoe, or some other variation. It might be prominent and obvious on endoscopy, or it might be an inconspicuous slit that can be identified only on close examination. A characteristic mucosal vascular pattern that surrounds the ureteral orifice might be helpful in these cases. Prominent mucosal vessels are often seen coursing in an arc medial, inferior, and lateral to the orifice unless they are obscured by an inflammation (Bagley et al, 1985). The ureteral orifice may be quite variable in position and appearance. Lyon and colleagues (1969) suggested categorizing the ureteral orifice according to these two criteria. They described the orifice as being in position A: if it was in the normal medial aspect of the trigone. Position C was at the junction of the trigone and lateral bladder wall or on the lateral wall proper; position B was between A and C. They also graded the ureteral orifice according to its configuration: grade 0, the normal cone or volcano orifice; grade 1, the stadium orifice; grade 2, the horseshoe orifice; and grade 3, the golf-hole orifice. These configurations were associated with an increasing tendency to laterality and reflux as the grade progressed. The normal ureter is easily distensible; however, there are three naturally narrow sites within the lumen. The narrowest portion is the 11
20 Anatomy Review of literature ureterovesical junction. This requires dilation before introduction of large caliber instruments. The other two narrow areas are at the pelvic brim and the ureteropelvic junction. These are relatively wider and are sufficiently dilated with irrigating fluid pressure to allow instrument passage. These areas are identified endoscopically by a slightly stenotic appearance and relative nondistensibility. Because the kidney lies posteriorly, the proximal aspect of the ureter passes posteriorly and laterally over the psoas muscle to enter the renal pelvis. The normal renal pelvis is usually conical in shape, with the apex of the cone leading to the ureteropelvic junction. It may also be more box-shaped, with the ureteropelvic junction near the lower medial angle. The intrarenal pelvis is often small with short major calyces. The extrarenal pelvis, on the other hand, is usually large, and because it lies outside the renal sinus, the major calyceal infundibula are usually long (Bagley and Rittenberg, 1987). As the ureteroscope enters the renal pelvis, the first structures to be seen are the ostia of the major calyces. These are circular openings with carinae separating the individual calyces. A long tubular infundibulum connects each ostium to the apex of the major calyx, which then branches into the minor calyces. These are the next structures visible as the ureteroscope enters the infundibulum. The ureteroinfundibular angle represents the angle of deflection necessary for a flexible ureteroscope to move from the axis of the upper section of the ureter to the axis of the lower infundibulum. This is found to be 140⁰ on average; although it may range from 104 to 175⁰. The minor calyces can contract periodically with obliteration of their lumen. This is due to a circular layer of muscle fibers that extends around the base of the papilla to help propel urine from the papillary ducts. An inner 12