CORRELATION OF CT-BASED STONE DENSITY AND SIZE WITH OUTCOMES OF PERCUTANEOUS NEPHROLITHOTOMY IN RENAL CALCULI PATIENTS: A RETROSPECTIVE STUDY
Main Article Content
Keywords
percutaneous nephrolithotomy; Hounsfield units; renal calculi; stone density; non-contrast CT; PCNL outcome; Uttar Pradesh
Abstract
Background: Percutaneous nephrolithotomy (PCNL) is the gold standard for renal stones
>2 cm. Pre-operative non-contrast computed tomography (NCCT) stone attenuation in Hounsfield Units (HU) and dimensions are increasingly utilized to predict surgical outcomes, but comprehensive data from tertiary centres in North India remain limited.
Objectives: To correlate pre-operative CT-based stone density (mean HU) and largest stone diameter with PCNL outcomes—specifically stone-free rate (SFR) at 4 weeks, operative time, haemoglobin drop, hospital stay, and complications using the modified Clavien–Dindo classification—in adults at Saraswati Medical College, Unnao.
Methodology: A retrospective record review was conducted encompassing 118 consecutive adult patients who underwent standard 24–30Fr PCNL between July 2019 and February 2020. Pre-operative NCCT mean HU (using free-draw regions of interest) and maximum stone diameter were extracted by a radiologist blinded to outcomes. Descriptive and inferential statistical analyses (independent t-tests, Pearson correlation, ROC curve, and multivariable logistic regression) were performed using SPSS v23.0 following institutional ethical clearance.
Results: The cohort (mean age 41.7±12.6 years; 71.2% male) had a mean stone diameter of
22.4±7.8 mm and mean HU of 982±312. The SFR at 4-week NCCT was 79.7%. Stones >25 mm and density >1000 HU independently lowered SFR (aOR 3.21, p=0.014 and aOR 2.78, p=0.022 respectively for non-stone-free status). The high-density cohort (>1000 HU) experienced longer mean operative times (94.2 vs 71.6 min, p<0.001) and greater haemoglobin drops (1.6 vs 0.9 g/dL, p=0.002). ROC analysis identified an HU cut-off of 1043 predicting residual stones (AUC 0.78, sensitivity 71%, specificity 74%). Overall Clavien complications occurred in 18.6%, predominantly low-grade (I–II).
Conclusion: Pre-operative NCCT-derived stone density and diameter independently predict PCNL outcome in this North Indian demographic. An HU cut-off near 1040 serves as a practical threshold to triage patients toward staged PCNL, mini-PCNL, or pre-emptive transfusion planning.
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Dr. Yadav Hardik Jagdishkumar
Assistant Professor, Department of Urology, Saraswati Medical College, Unnao, UP, India
Dr. Darji Parth Jitendrakumar
Assistant Professor, Department of Radio-Diagnosis, Saraswati Medical College, Unnao, UP, India
