Cesare Marco Scoffone, András Hoznek and Cecilia Maria Cracco (eds.)Supine Percutaneous Nephrolithotomy and ECIRS2014The New Way of Interpreting PNL10.1007/978-2-8178-0459-0_4
© Springer-Verlag France 2014
4. PNL: Indications and Guidelines: Urolithiasis
(1)
Department of Urology, Muljibhai Patel Urological Hospital, Civil Hospital Road, Nadiad, 387001, Gujarat, India
Abstract
It is essential to clearly define the indications for PNL according to established guidelines for the treatment of urolithiasis. A thorough preoperative workup should identify stone (size, location, composition and hardness) and patient features (including special situations like urinary malformations, skeletal deformities, paediatric age or pregnancy), in order to define the indication to the percutaneous approach and possibly find out the best candidates for the supine position.
4.1 Introduction
The American Urological Association (AUA) has been the frontrunner in formulating guidelines for urolithiasis since 1991. Since then, a number of editions of guidelines have been published, the 2005 guidelines on staghorn calculi being the latest [1]. The European Association of Urology (EAU) has published similar guidelines since 2000. The latest updates have been published in 2012 [2].
4.2 Indications for PNL According to the Guidelines
The factors which determine the indications for PNL include stone factors (stone size, stone composition, stone location), patient factors (body habitus, renal anomalies) and previous failure of other treatment modalities (extracorporeal shock wave lithotripsy, flexible ureteroscopy or other surgery).
The usual indications for PNL are stones larger than 20 mm2, staghorn stones, partial staghorn calculi and stones in patients with chronic kidney disease. The contraindications for PNL include pregnancy, bleeding disorders and uncontrolled urinary tract infections [2].
4.3 Preoperative Workup
The recommendations and guidelines suggest intravenous urography (IVU) as the gold standard in the preoperative workup for urolithiasis. Non-contrast computerised tomography (NCCT) scan is quick and safe, contrast-free alternative to IVU. Randomised studies have shown that NCCT has similar or superior results to excretory urography in acute flank pain [4]. Contrast media should not be given or should be avoided when there is an elevated creatinine level, pregnancy or lactation [5, 6]. Additional information can be gained by contrast-enhanced CT scan (CTU); however at the moment there is no level 1 evidence to suggest that CTU is superior to IVU in the workup of urolithiasis [7]. Computerised tomography (CT) is a useful tool in planning PNL, particularly in anomalous kidneys [8]. Besides identification of stones, CT provides information regarding selection of appropriate treatment modality. It helps in this regard, by providing information regarding the size, number and attenuation number of the stone, presence and degree of hydronephrosis and skin to stone distance. All these factors help in determining the selection of appropriate treatment modality. X-ray KUB and ultrasound are used by few clinicians as a measure of preoperative investigations; however this cannot be considered as a standard. These investigations help to plan access and predict the possible success rates. Ultrasound is useful as a tool in the preoperative workup if the method of access is ultrasound guided.
Recently the applicability of 3D reconstruction is described for planning percutaneous access. Staghorn stone volume and its distribution (“staghorn morphometry”) predict the requirement of tract and stage for PNL monotherapy, also helping to classify staghorn calculi accordingly. The model of staghorn morphometry differentiates staghorn into type 1 (single tract and stage), type 2 (single tract-single/multiple stage or multiple tract-single stage) and type 3 (multiple tract and stage) [8].
The EAU guidelines [2] state that for all patients with infection stones, recent history of urinary tract infection and bacteriuria, antibiotics should be administered before the stone-removing procedure and continued at least for 4 days afterwards. For septic patients with obstructing stones, urgent decompression of the collecting system with either percutaneous drainage or ureteral stenting is indicated. Definitive treatment of the stone should be delayed until sepsis is resolved.
4.4 Stone Factors
4.4.1 Stone Size
PNL monotherapy is the treatment of choice for “large stones”. Generally speaking the definition of large stones includes those which measure 2 cm in diameter [9]. PNL attains stone-free rates up to 95 %, as it offers direct removal of stone fragments through the nephrostomy tract. For stones smaller than 2 cm in size, the treatment algorithm becomes more complicated because of the multiple variables involved. AUA guidelines recommend PNL as a treatment of choice for staghorn calculi. A retrospective study with 200 patients has shown that renal deterioration occurs in 28 % of patients with staghorn calculi treated conservatively. This emphasises the fact that staghorn stones should be aggressively and surgically managed [10]. PNL should be the recommended modality for staghorn calculi as clearance rates are greater three times than those reported for ESWL [11].
The following are the treatment options in staghorn calculi [1]:
1.
PNL should be the first treatment utilised for most patients (level 2 of evidence).
2.
ESWL should not be used as the preferred treatment modality for staghorn stones.
3.
Open surgery should be recommended only if the stones are not expected to be removed in a reasonable number of stages.
4.
Nephrectomy should be considered in nonfunctioning kidneys.
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