Login to Access Video or Poster Abstract: MP75-13
Sources of Funding: none

Introduction

To propose a scoring system to standardize and grade the complexity of flexible ureteroscopic lithotripsy (FURL) for renal calculi. The current predict methods available for percutaneous nephrolithotomy (PCNL) are not validated for FURL procedures.

Methods

The C.R.E.A.M. score comprises 5 reproducible variables from non-enhanced CT: (C)ount of stone number, (R)elationship between stone and parenchyma, (E)ssence of stone density, (A)rea the stone locates in, and (M)easurement of stone burden. Each of components is scored on a 3-grade scale. We first propose a novel method to standardize the stone location without considering the anatomical features of collection system. A vertical axis line through the highest point of lower lip (HPL) of renal pelvis, a horizontal line from HPL to middle parenchyma, and a 45 degree diagonal line from HPL to lower parenchyma are drawn on coronal plane of kidney. The collection system is segmented to 3 areas by the lines (diagram resembles lower case letter &[prime]k&[prime]), which we named K-Segmentation. The C.R.E.A.M. score was validated on 112 consecutive FURL procedures performed by one single experienced surgeon in our tertiary medical center.

Results

The mean C.R.E.A.M score was 9.6 (range 5-15). The immediate stone-free rate (SFR) was 58.0% confirmed by plain film obtained on first postoperative day. The score correlated with the operation time (P<0.001). The patients with residual stones had significant higher scores than those with stone free (10.7 vs 8.3, P<0.001). Additionally, the SFR of simple (score 5-8), medium (score 9-12), and complex (score 13-15) group were 77.6%, 54.2%, 6.7%, respectively. There was significant difference between groups (P<0.001). 20 complications (17.9%) were recorded. All were postoperative urosepsis including 3 Clavien grade one and 17 Clavien grade two. The distribution was 5 (10.2%) in simple, 10 (20.8%) in medium, and 5 (33.3%) in complex group.

Conclusions

The C.R.E.A.M. score can be applied to accurately predict the outcome of FURL procedure. For complex renal stones with high C.R.E.A.M scores, the SFR after FURL would be extremely low and other modalities such as PCNL should be considered.

Funding

none