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6.5 Percutaneous surgery versus eswl for removal of renal stones

PNL and ESWL are complementary rather than competing procedures. Principally, the indication for PNL can also be extended to include so-called 'easy cases' when ESWL is not available. Stones below 2 cm in diameter in the renal pelvis or the upper and middle caliceal group without obstruction and dilatation of the collecting system are generally accepted as ideal indications for ESWL. Lower pole stones have a clearance rate of less than 50% and the percutaneous procedure is preferential if the calix is obstructed, if the stone is larger than 2 cm in diameter, or if the infundibulum is long and the infundibulopelvic angle is steep (1-3).

6.5.1 Malformations

In horseshoe kidneys, spontaneous passage of fragments after ESWL can only be expected if there is no obstruction and no high insertion of the ureter. Otherwise, PNL is preferred. Stones in caliceal diverticula are frequently very dense and respond poorly to ESWL. Stone clearance is achieved in less than 20% of cases. Percutaneous procedures are difficult, but in the hands of an experienced surgeon are generally successful (4).

6.5.2 Stone composition

Dense, round calculi with a smooth surface are frequently composed of either brushite or calcium oxalate monohydrate. In these cases, ESWL leads to large fragments that do not pass easily (5). PNL should be preferred in these cases as in patients with cystine stones that respond poorly to ESWL. Uric acid stones are best treated with oral chemolysis. ESWL plus stenting is possible, but it is difficult to determine the fragment size and need for further sessions, and larger fragments that pass into the ureter may require frequent retrograde manipulations.

6.5.3 References

1. Lingeman JE, Siegel Yl, Steele B, Nyhuis AW, Woods JR.

Management of lower pole nephrolithiasis: a critical analysis. J Urol 1994; 151: 663-667.

2. Bon D, Dore B, Irani J, Morroncle M, Aubert J.

Radiographic prognostic criteria for extracorporeal shock-wave lithotripsy: a study of 485 patients. Urology 1996; 48: 556-560.

3. Netto NR Jr, Claro JF, Lemos GC, Cortado PL.

Renal calculi in lower pole calices: what is the best method of treatment? J Urol 1991; 146: 721-723.

  1. Shalhav AL, Soble JJ, Nakada SY, Wolf JS Jr, McClennan BL, dayman RV. Long-term outcome of caliceal diverticula following percutaneous endosurgical management. J Urol 1998; 160: 1635-1639.

  2. Dretler SP.

Special article: calculus breakability - fragility and durility. J Endourol 1994; 8: 1-3.

6.6 Devices for endoscopic disintegration of stones

6.6.1 Ballistic lithotripsy

Ballistic lithotripsy involves a device in which alternating compression caused by air or electromechanical forces is transmitted to a metal rod. Pulses drive a metallic bullet that bumps the end of the rod against the stone. Rods are 2.4-6 F in diameter and can be used through a semi-rigid ureteroscope and all rigid endoscopes. A similar effect is obtained by alternating mechanical displacement.

6.6.2 Ultrasonic lithotripsy

These commercially available units consist of a power generator, an ultrasound transducer and a probe, forming the sonotrode. A piezoceramic element in the handle of the sonotrode is stimulated to resonate, and this converts electrical energy into ultrasound waves (frequency: 23,000-27,000 Hz). The ultrasound waves are transmitted along the hollow metal probe to create a vibrating action at its tip. When the vibrating tip is brought into contact with the surface of a stone, the calculus can be disintegrated. The probes, which are available in sizes 10 F and 12 F, are passed through the straight working channel of a rigid ureteroscope or nephroscope. Suction tubing can be connected to the end of the sonotrode.

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