JOURNAL CLUB

PERCUTANEOUS NEPHROLITHOTOMY GUIDED SOLELY BYULTRASONOGRAPHY

A 5-YEAR STUDY OF >700 CASES

Song Yan, Fei Xiang and Song YongshengDivision of Urology, Sheng Jing Hospital,

China Medical University, Shenyang, China

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

INTRODUCTION Percutaneous nephrolithotomy (PCNL) has

been performed as a minimally invasive method of removing kidney stones since 1976.

Because of the improvements in technique and equipment, PCNL is now considered to be a generally safe management option, with a low incidence of complications [1,2]

1. Wen CC, Nakada SY. Treatment selection and outcomes: renal calculi. Urol Clin North Am 2007; 34: 409–19

2. Lingeman JE, Miller NL. Management of kidney stones. BMJ 2007; 334: 468–72

Pelvicalyceal system (PCS) access is key to successful PCNL and is generally performed under fluoroscopic guidance.

Although protective gowns can be used by patients and physicians during these procedures, radiation exposure can still affect the surgical team over the long term, and the hazard is dose-independent [3].

3. Safak M, Olgar T, Bor D, Berkmen G, Gogus C. Radiation doses of patients and urologists during percutaneous nephrolithotomy. J Radiol Prot 2009; 29: 409–15

The use of ultrasonography (US) can avoid radiation exposure and provides a reliable method for the localization of renal stones, especially non-opaque stones that are not visible via fluoroscopy.

Moreover, colour US can be used as a tool for the localization of intrarenal arteries and helps to avoid their puncture by a Chiba needle [4,5].

4. Lu M-H, Pu X-Y, Gao X, Zhou X-F, Qiu J-G, Tu S-T. Comparative study of clinical value of single B-mode ultrasound guidance and B-mode combined with color Doppler ultrasound guidance in mini-invasive percutaneous nephrolithotomy to decrease hemorrhagic complications. Urology 2010; 76: 815–20

5. Tzeng B-C, Wang C-J, Huang S-W, Chang C-H. Doppler ultrasound-guided percutaneous nephrolithotomy: a prospective randomized study. Urology 2011; 78: 535–9

Osman et al. [6] suggested that PCNL punctures should be carried out under US guidance; however, they completed the rest of the procedure under fluoroscopic guidance.

Some studies [7,8] have recommended the use of PCNL guided solely by US for single stones in moderately to markedly dilated PCSs by an experienced urologist

6. Osman M, Wendt-Nordahl G, Heger K, Michel MS, Alken P, Knoll T. Percutaneous nephrolithotomy with ultrasonography- guided renal access: experience from over 300 cases. BJU Int 2005; 96: 875–8

7. Hosseini M, Hassanpour A, Farzan R, Yousefi A, Afrasiabi MA. Ultrasonography guided percutaneous nephrolithotomy. J Endourol 2009; 23: 603–7

8. Gamal WM, Hussein M, Aldahshoury M, Hammady A, Osman M, Moursy E, Abuzeid A. Solo ultrasonography-guided percutanous nephrolithotomy for single stone pelvis. J Endourol 2011; 25: 593–6

Mayank et al. [9] suggested US as an adjunct to fluoroscopy for renal access in PCNL; however, a large series is still needed to prove the safety and efficiency of PCNL guided solely by US in various stone cases. In the present study, we reported our experience and evaluated the feasibility and efficacy of PCNL performed solely under US guidance.

9. Agarwal M, Agrawal MS, Jaiswal A, Kumar D, Yadav H, Lavania P. Safety and efficacy of ultrasonography as an adjunct to fluoroscopy for renal access in percutaneous nephrolithotomy (PCNL). BJU Int 2011; 108: 1346–9

PATIENTS AND METHODS From May 2007 to July 2012, 705 24-F-tract

PCNL procedures were performed (679 patients, of whom 26 had bilateral stones).

Calyceal puncture and dilatation were performed under US guidance in all cases.

The procedure was evaluated for access success, length of postoperative hospital stay, complications (modified Clavien system) [10], stone clearance and the need for auxiliary treatments.

10. 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: 246–55

The inclusion criteria permitted the inclusion of patients with single pelvic or calyceal stones >2.0 cm in diameter or with multiple or staghorn stones.

Stones refractory to ESWL and proximal ureteric stones >1.5 cm in diameter were also included.

Patients were not excluded if they had a history of open renal stone surgery or if they had impaired renal function.

Patients with an ectopic kidney or urosepsis were excluded from the study.

Characteristic: Mean (SD) age 49 (7) Gender, n (%)

M 409 (60.2) F 270 (39.8)

Laterality, n (%) Left 365 (51.8) Right 314 (44.5)

Bilateral 26 (3.7) Stone type, n (%)

Pelvic or upper ureter 114 (16.2) Calyxeal 211 (29.9) Multiple or Staghorn 380 (53.9)

Mean (SD) stone burden, mm2 453.86 (131.63) Grade of hydronephrosis, n (%)

None 69 (9.8) Mild 191 (27.1) Moderate 267 (37.9) Severe 178 (25.2)

Histories of open renal stone surgeries, n (%) 26 (3.7) Abnormality, n (%)

Solitary kidney 8 (1.1) Horse shoe kidney 13 (1.8) Medullary sponge kidney 5 (0.7) Vertebral deformity 4 (0.6)

Demographic and clinical characteristics of the 679 patients in the study.

PATIENT ASSESSMENT Medical history Physical examination Urine analysis & urine culture Renal function test Coagulation test. All patients underwent unenhanced CT or

i.v.urography to clarify the size and location of the calculi and the grade of hydronephrosis, before undergoing surgery.

During their hospital stay, all patients were prescribed parenteral antibiotics, according to their urine culture results, to minimize the incidence of UTIs.

Under general or epidural anaesthesia. Epidural anaesthesia was usually preferred because patients were able to cooperate with the surgical team when the position was changed. General anaesthesia was used only when epidural anesthesia was not suitable for a patient.

One surgical team performed all the operations.

Initially, US was performed to detect the presence of organs in the path of the puncture to avoid organ injury.

For a single stone involved one calyx or staghorn stones involved one calyx and the pelvic, the calyx harbouring the stone was chosen.

For a single pelvic stone, a posterior middle calyx puncture, via the 12th subcostal space between the posterior axillary line and scapula line, was preferred. This allowed access to the renal pelvis and more convenient observation of the collecting system.

For staghorn stones, to use the one-tract approach, the middle calyx was chosen in most of the cases, as this provides more convenient access for a nephroscope to the other calyces.

To use a multiple-tract approach, the upper pole puncture was usually preferred as the first puncture site.

In the absence of hydronephrosis, saline was infused through the ureteric catheter to ensure the ballooning of the PCS. Mild hydronephrosis was sufficient to access the targeted calyx.

A colour-Doppler US system with a 3.5-MHz transducer (Hitachi Aloka, Tokyo, Japan) was used in this study.

An 18-gauge co-axial needle was introduced into the most convex point of the targeted calyx under US guidance, either freehand or using a needle-guiding system fixed to the US probe.

A US-guided puncture through the cup of the desired calyx to traverse a minimum of cortical tissue and establish the shortest straight tract between the skin and calyx, avoiding visceral injury.

18- gauge needle Target calyx

(A)Percutaneous puncture of a selected calyx was performed under real-time US guidance.

(B) An 18-gauge needle entering the target calyx is shown on US.

A B

At the end of the procedure, the patient’s stone-free status was double-checked using US and a flexible nephroscope.

For large staghorn stones occupying several calyces, which were difficult to remove using a single tract, a second or third tract was created using the same technique to help remove the stones.

The operating time was defined as the time from introduction of the 18-gauge co-axial needle into the patient’s skin until the placement of the nephrostomy tube.

POST-OPERATIVE PERIOD A blood count test was performed on the first

postoperative day to assess the change in the patient’s haematocrit level.

In addition, on this day, the Foley catheters were removed if haematuria was not evident.

The ureteric catheter was routinely replaced by

a JJ stent at the end of the primary operation, and this stent was maintained in place for 3 weeks postoperatively to facilitate the passage of residual fragments and drainage of blood clots.

Stone-free status was defined as the absence of visible fragments on CT.

Clinically insignificant residual fragments (CIRFs) were defined as those that were <4 mm in diameter, non-obstructive, and asymptomatic.

CT was routinely performed for residual stones 48 h and 4 weeks after surgery; re-PCNL, ureteroscopy, and ESWL were considered as auxiliary treatments, when indicated.

In patients who were considered stone-free or with CIRFs, the nephrostomy tubes were removed 72 h after operation; however, the nephrostomy tube was left in place if a second PCNL session was planned owing to the presence of residual stones.

RESULTS Access to the PCS was successful in all cases.

The mean (SD) operating time was 66 (25) min, with 618 (91.0%) patients receiving epidural and 61 (9.0%) receiving general anaesthesia.

Of the total patient population, 626 (91.5%) patients were treated in the prone supine and 53 (8.5%), in the lateral flank position.

Although most of the cases, e.g. 594 (84.3%) cases, were managed successfully by a single tract, a second tract was used in 85 (12.1%) cases, and 26 (3.7%) patients required a third tract.

The mean (SD) postoperative hospital stay was 3.98 (1.34) days, with the patients showing a mean (SD) decline in haemoglobin levels of 2.24 (2.02) g/L.

Complete clearance was confirmed by CT, conducted 48 h after surgery in 63.5% of the patients.

The stone-free rate was 70.5% among patients with a single calculus (229 of 325 cases) and 57.1% in cases involving staghorn or multiple calculi (217 of 380 cases).

CIRFs were confirmed by CT performed 48 h after surgery in 77 (20.6%) cases involving a single calculus (77 of 325 cases) and in 80 (21.1%) cases involving staghorn or multiple calculi (80 of 380 cases).

Auxiliary treatments, including ESWL in 52 patients, re-PCNL in 41 patients and ureteroscopy in 18 patients, were performed 1 week after the primary procedure in 111 (15.7%) cases for residual stones >4 mm in size.

The overall stone-free rate at 4 weeks after the ancillary procedures was 87.4%, with stone-free rates of 92.6% associated with cases of simple stones and 82.9% for those involving complex stones

CT was used to confirm the initial stone-free status determination made in 447 of 469 cases and confirm the CIRF determination made in 147 of 165 cases; the initial determinations were made intra-operatively by US and flexible nephroscopy.

The sensitivities of intra-operative US-guidance and flexible nephroscopy for detecting significant residual stones and clinically insignificant residual fragments were 95.3 and 89.1%, respectively.

Some of the larger, US-detected, residual stones were not extracted because of the increased risk of haemorrhage.

Variable ( RESULT OF US-GUIDED PCNL)Number of access attempts required, n (%)

1 594 (84.3)2 85 (12.1)≥3 26 (3.7)

Anaesthesia, n (%)Epidural 618 (91.0)General 61 (9.0)

Position, n (%)Flank 53 (8.5)Prone 626 (91.5)

Mean (SD) operating time, min 66 (25)Mean (SD) decline in haemoglobin level, g/L 2.24 (2.02)Mean (SD) postoperative hospital stay, days 3.98 (1.34)Mean cost (operation, medicine and peri-operative examinations),$ 4611.15Stone-free rate confirmed by CT 48 h after one stage operation,n/No. of cases (%) 447/705 (63.4) Single 243/325 (74.8)

Multiple or Staghorn 204/380 (53.7)CIRF after one stage operation, n/No. of cases (%) 147/705 (20.9)

Single 67/325 (20.6)Multiple or Staghorn 80/380

(21.1)Fragments >4 mm after one-stage operation, n/No. of cases (%) 111/705

Single 15/325 (4.6)Multiple or Staghorn 96/380

(25.3)Ancillary procedures for stone residues >4 mm after operation, n/No. of cases (%)111/705 (15.7)

Second- or third-stage PCNL 41/111 (36.9)ESWL 52/111 (46.8)Ureterscopy 18/111 (16.2)

Overall stone-free rate at 4 weeks after operationconfirmed by CT, n/No. of cases (%)616/705 (87.4)

Single 301/325 (92.6)Multiple or Staghorn

315/380 (82.9)

Complication n (%)Total no. of complications 113 (16.0)Grade 1 94 (13.3)

Nephrostomy tube displacement 7 (1.0)Transient fever <38 °C 87 (12.3)

Grade 2 17 (2.4)Haemorrhage requiring transfusion (3-single & 9-multiple tract) 12 (1.7)Non-septic infections requiring additional antibiotics(instead of prophylactics)

UTI 3 (0.4)Pneumonia 2 (0.3)

Grade 3 2 (0.3)Grade 3a: perirenal haematoma needing intervention 1(0.15)Grade 3b: haemorrhage requiring embolism 1 (0.15)

Grade 4 0Grade 5 0

DISCUSSION Percutaneous nephrolithotomy is the primary procedure

for the management of patients with renal stones who are not candidates for ESWL.

Fluoroscopic guidance has been used to guide the

percutaneous renal access, establish the working tract and perform the stone manipulation.

The use of US guidance has other advantages in addition to being free of ionizing radiation; for example, it results in fewer punctures, has shorter operating times and avoids contrast-related complications [12].

12. Basiri A, Ziaee SA, Nasseh H et al. Totally ultrasonography guided percutaneous nephrolithotomy in the flank position. J Endourol 2008; 22: 1453–7

This form of guidance allows imaging of the intervening structures with the benefit of minimizing the risk of injury to nearby organs.

Moreover, the use of US at the end of the procedure helps the urologist to look for non-opaque and semi-opaque residual stones that are not visualized by radiography [13].

The European Association of Urology recommends initial puncture under US guidance because it reduces radiation hazards [14].

13. Basiri A, Ziaee A, Kianian H, Mehrabi S, Karami H, Moghaddam S. Ultrasonographic versus Fluoroscopic Access for Percutaneous Nephrolithotomy: a Randomized Clinical Trial. J Endourol 2008; 22: 281-4

14. European Association of Urology. Guidelines on urolithiasis. 2012 http://www.uroweb.org/gls/pdf/21_Urolithiasis_LR.pdf

This technique was safe and reliable, and no faulty dilatation was found in this study.

During the study, there was just one case in which the operator failed to establish the working channel in the first attempt because of the accidental dislodging of the guidewire; however, a second attempt was made and the operation was completed successfully without any complications.

100% access to the kidney as well as 87.4% complete stone clearance, were achieved. The stone-free rate in this series was comparable with the rates gained from PCNL results reported in other series under either US or fluoroscopic guidance [15,16].

Osman et al. [17] reported that the sensitivity of plain abdominal film of kidney, ureter and bladder (KUB) for detecting stone-free rates was 40.3% and that of US was 37.1%.

15. Shoma AM, Eraky I, El-Kenawy M, El-Kappany HA. Percutaneous nephrolithotomy in the supine position: technical aspects and functional outcome compared with the prone technique. Urology 2002; 60: 388–92

16. Basiri A, Mohammadi Sichani M, Hosseini SR et al. X-ray-free percutaneous nephrolithotomy in supine position with ultrasound guidance.World J Urol 2010; 28: 239–44

17. Osman Y, El-Tabey N, Refai H et al. Detection of residual stones after percutaneous nephrolithotomy: role of non-enhanced spiral computerized tomography. J Urol 2008; 179: 198–200

The sensitivities of KUB and US for detecting significant residual stones were reported to be 58.3 and 41.6%, respectively; for detecting CIRFs, the reported sensitivities were 15.3 and 30.7%, respectively; however, Alan et al. [18] reported that the sensitivities of US for detecting significant residual stones and CIRFs were 83.3 and 87.5%, respectively, based on KUB detection.

In their study, the stone-free status was double-checked during the operation using a flexible nephroscope and US, but CT was also routinely performed to confirm the residual stone status on the second postoperative day.

18. Alan C, Kocoğlu H, Ates F, Ersay AR. Ultrasound-guided X-ray free percutaneous nephrolithotomy for treatment of simple stones in the flank position. Urol Res 2011; 39: 205–12

Percutaneous nephrolithotomy is usually performed with the patient in a prone position, but this prone position has several disadvantages. For example, PCNL with the patient in this position is difficult when the patient is obese or has spinal anomalies or cardiovascular disease [19].

Karami et al. [20] reported performing PCNL under US guidance in 40 patients in the lateral position with an access rate of 100% and a complete stone-removal rate of 85%.

In the present study, PCNL was performed in the lateral position for the 53 patients who had insufficient cardiac output or pulmonary disease and US guidance was proven to be a safe and convenient procedure in both positions.

19. Manohar T, Jain P, Desai M. Supine percutaneous nephrolithotomy: effective approach to high-risk and morbidly obese patients. J Endourol 2007; 21: 44–9

20. Karami H, Arbab AH, Rezaei A, Mohammadhoseini M, Rezaei I. Percutaneous nephrolithotomy with ultrasonography-guided renal access in the lateral decubitus flank position. J Endourol 2009; 23: 33–5

CONCLUSION Total US-guided PCNL is safe and convenient,

and may be performed without any major complications and with the advantage of preventing radiation hazards and damage to adjacent organs.

CONFLICT OF INTEREST None declared.

CRITICAL ANALYSISPROS Good number Performed by single surgical unit at one health

centre No mortality with optimum complications (16%)

CONS Cross sectional study No comaparision with standard fluroscopy guided

puncture 16% required auxillary procecures Usage of DJ stents in all cases requiring intervention

to remove them.