Prospective evaluation of outcome of percutaneous nephrolithotomy using the ‘STONE’ nephrolithometry score: A single-centre experience

Abstract

ObjectiveTo assess the prediction of stone clearance and complications of percutaneous nephrolithotomy (PCNL) using the ‘STONE’ nephrolithometry score, assessing stone size, tract length (skin-to-stone distance), degree of obstruction, number of calyces involved and stone essence (density).Patients and methodsThis was a prospective study of patients undergoing single-tract PCNL while prone, conducted at a university hospital. All patients had non-contrast-enhanced computed tomography within 3 weeks of the procedure. Only patients with a unilateral procedure and radio-opaque stones were included. The five variables of the STONE nephrolithometry score were calculated before the procedure. The stone-free rates were assessed with a plain abdominal film at 4 weeks and complications were graded using the modified Clavien system.ResultsIn all, 107 patients were included in the final analysis. Overall, 80% of patients were rendered stone-free. Among the individual variables, a larger stone (P = 0.002) and the involvement of multiple calyces (P = 0.04) were associated with residual stones, while tract length (skin-to-stone distance), stone density and presence of hydronephrosis were not. Patients who were rendered stone-free had a statistically significant lower overall STONE score than those with residual stones, at 7.24 vs. 8.14 (P = 0.02). The score also correlated with operative duration, which was significantly longer with a higher STONE score (P = 0.03). The complication rate was 18% and most complications were Clavien grade 2, with bleeding requiring a blood transfusion (11 patients) being the commonest. There were no deaths within 30 days of surgery, but there was no correlation between the STONE score and complications.ConclusionThe STONE nephrolithometry score is a simple and easy to apply system for predicting complexity in stone clearance with PCNL.

Comparative testing of reliability and audit utility of ordinal objective calculus complexity scores. Can we make an informed choice yet?

“…Thus, it is understandable why a model that is designed to optimally statistically predict SFR may not do well when applied to other outcomes. We thus find it not surprising when conflicting data exists for the association of ordinal, as well as the CROES score, with complications (with more favourable data for ordinal scores) [9,10,[13][14][15]19,21]. These conflicting reports can be explained by issues of sample size, variations in expertise, patient-related factors (comorbidities), and surgical approach characteristics.…”

“…and CROES scores also found to be associated with complications), although cross-comparative studies have been fewer [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The only systematic review concluded with ambiguity over the clear superiority of any one system and recommended further validation studies [23].…”

Prospective Study of Percutaneous Nephrolithotomy in the Management of Renal Calculi

“…In this study, most patients who required additional postoperative procedures had staghorn or multiple calculi. Farhan et al 37 in their study found that among patients with residual stones, six (29%) had additional treatments, with shock-wave lithotripsy in four and semi-rigid ureteroscopy and JJ stenting in one each. Average hospital stay was 5.5 days.…”

Non-contrast CT in the Evaluation of Urinary Tract Stone Obstruction and Haematuria

“…Predicting complications and success of percutaneous surgery for urolithiasis can now be reliably done using one of the several nephrolithometry scores [22]. Nephrolithometry scoring systems are based on pre-operative stone and patient features and they demonstrate and stratify relationships between kidney's anatomy and stones.…”

“…Stone size, composition, location, skin to stone distance, etc. are some of the well recognised parameters used in the risk stratiication and predicting success of treatment [22].…”