A novel method for prediction of stone composition: the average and difference of Hounsfield units and their cut-off values

The mean Hounsfield unit range acquired from different slices produces superior predictive accuracy for pyonephrosis in obstructive uropathy

PURPOSE

To determine the non-contrast computer tomography imaging features of pyonephrosis and evaluate the predictive value of Hounsfield units (HUs) in different hydronephrotic region slices.

MATERIALS AND METHODS

We retrospectively reviewed data from patients with hydronephrosis who had renal-ureteral calculi. All patients were categorized into pyonephrosis and simple hydronephrosis groups. Baseline characteristics, the mean HU values in the maximal hydronephrotic region (uHU) slice, and the range of uHU in different slices (ΔuHU) were compared between the two groups. Univariate and multivariate analyses were performed to identify risk factors for pyonephrosis.

RESULTS

Among the 181 patients enrolled in the current study, 71 patients (39.2%) were diagnosed with pyonephrosis. The mean dilated pelvis surface areas were comparable between patients with pyonephrosis and simple hydronephrosis (822.61 mm² vs. 877.23 mm², p=0.722). Collecting system debris (p=0.022), a higher uHU (p=0.038), and a higher ΔuHU (p<0.001) were identified as independent risk factors for pyonephrosis based on multivariate analysis. The ΔuHU sensitivity and specificity were 88.7% and 86.4%, respectively, at a cutoff value of 6.56 (p<0.001), whereas the sensitivity and specificity for detecting pyonephrosis at a uHU cutoff value of 7.96 was 50.7% and 70.9%, respectively (p=0.003).

CONCLUSIONS

Non-contrast computer tomography was shown to accurately distinguish simple hydronephrosis from pyonephrosis in patients with obstructive uropathy. Evaluation of the ΔuHU in different slices may be more reliable than the uHU acquired from a single slice in predicting pyonephrosis.

Robot-assisted anatrophic nephrolithotomy for complete staghorn stone

To assess the efficacy and safety of robot-assisted anatrophic nephrolithotomy (RANL) as a choice of minimally invasive treatment for patients with complete staghorn stone. In a single-tertiary referral center retrospective study, 10 consecutive patients underwent RANL for complete staghorn stone. After dissection to the renal hilum and clamping of the renal vessels, an incision was made along the Brodel line and exposed the collecting system to extract the stone. Then, the collecting system and parenchyma were closed in layers. The outcomes included reduction of the stone burden, short- and long-term postoperative kidney function, and pain score. The average age of patients was 54.6 years and body mass index was 27.58 kg/m2. Mean warm ischemia time was 28.40 minutes, mean robotic console time was 137 minutes, and mean estimated blood loss was 83 mL. The mean length of stay was 5.4 days and there were no severe perioperative complications. Eight of 10 patients had >90% reduction in stone burden and 5 (50%) patients were completely stone-free. There was no significant decrease in postoperative estimated glomerular filtration rate compared with preoperative values after 1 month and 1 year. Our experience with RANL demonstrated efficacy and safety in the minimally invasive treatment of complete staghorn stone in short- and long-term follow-up periods.

External validation of the R.I.R.S. scoring system to predict stone-free rate after retrograde intrarenal surgery

Background

The R.I.R.S. scoring system is defined as a novel and straightforward scoring system that uses the main parameters (kidney stone density, inferior pole stones, stone burden, and renal infundibular length) to identify most appropriate patients for retrograde intrarenal surgery (RIRS). We strived to evaluate the accuracy of the R.I.R.S. scoring system in predicting the stone-free rate (SFR) after RIRS.

Methods

In our medical center, we retrospectively analyzed charts of patients who had, between September 2018 and December 2019, been treated by RIRS for kidney stones. A total of 147 patients were enrolled in the study. Parameters were measured for each of the four specified variables.

Results

Stone-free status was achieved in 105 patients (71.43%), and 42 patients had one or more residual fragments (28.57%). Differences in stone characteristics, including renal infundibulopelvic angle, renal infundibular length, lower pole stone, kidney stone density, and stone burden were statistically significant in patients whether RIRS achieved stone-free status or not (P < 0.001, P: 0.005, P < 0.001, P < 0.001, P: 0.003, respectively). R.I.R.S. scores were significantly lower in patients treated successfully with RIRS than patients in which RIRS failed (P < 0.001). Binary logistic regression analyses revealed that R.I.R.S. scores were independent factors affecting RIRS success (P = 0.033). The area under the curve of the R.I.R.S. scoring system was 0.737.

Conclusions

Our study retrospectively validates that the R.I.R.S. scoring system is associated with SFR after RIRS in the treatment of renal stones, and can predict accurately.

Hounsfield unit attenuation value can differentiate pyonephrosis from hydronephrosis and predict septic complications in patients with obstructive uropathy

We aimed to assess the role of computerized tomography attenuation values (Hounsfield unit-HU) for differentiating pyonephrosis from hydronephrosis and for predicting postoperative infectious complications in patients with obstructive uropathy. We analysed data from 122 patients who underwent nephrostomy tube or ureteral catheter placement for obstructive uropathy. A radiologist drew the region of interest for quantitative measurement of the HU values in the hydronephrotic region of the affected kidney. Descriptive statistics and logistic regression models tested the predictive value of HU determination in differentiating pyonephrosis from hydronephrosis and in predicting postoperative sepsis. A HU cut-off value of 6.3 could diagnose the presence of pyonephrosis with 71.6% sensitivity and 71.5% specificity (AUC 0.76; 95%CI: 0.66-0.85). At multivariable logistic regression analysis HU ≥ 6.3 (p ≤ 0.001) was independently associated with pyonephrosis. Patients who developed sepsis had higher HU values (p ≤ 0.001) than those without sepsis. A HU cut-off value of 7.3 could diagnose the presence of sepsis with 76.5% sensitivity and 74.3% specificity (AUC 0.79; 95%CI: 0.71-0.90). At multivariable logistic regression analysis, HU ≥ 7.3 (p ≤ 0.001) was independently associated with sepsis, after accounting for clinical and laboratory parameters. Measuring HU values of the fluid of the dilated collecting system may be useful to differentiate pyonephrosis from hydronephrosis and to predict septic complications in patients with obstructive uropathy.

Clinician training level impacts prescribing practices for the conservative management of acute renal colic: a contemporary update

PURPOSE

Given the current and increasing awareness of the opioid crisis, this study aimed to characterise the types of analgesic prescription for conservatively managed renal colic.

METHODS

This was a retrospective cohort study of consecutive patients presenting to the Emergency Department (ED) in 2014-2019. Patients were included if they had radiographically confirmed obstructing calculus, managed conservatively without intervention, and were given a prescription for analgesia on discharge. Patient demographics were recorded and analysed. Opioid, non-opioid, and alpha-blocker medications were compared according to patient and disease parameters, and clinician training. Oral morphine equivalents (OMEs) were used to compare prescribed quantities. Subgroup analyses of stone size and location were performed.

RESULTS

Our analysis included 1761 patients with confirmed renal colic: median age of 50 years (16-96). Altogether, 88% of included patients were prescribed opioids on discharge, while only 68% were prescribed non-opioids (p < 0.001). Oxycodone immediate release was the most frequently prescribed analgesic. Logistic regression modelling controlling for patient and disease characteristics significantly predicted more non-opioid (p < 0.001) and alpha-blocker (p = 0.037) prescription with clinician training < 3 years. Linear regression modelling demonstrated that clinicians training < 3 years predicted lower OMEs per prescription compared to clinicians with ≥ 3 years of training (p = 0.001). Subgroup analyses supported similar predictions with training.

CONCLUSIONS

Prescribing patterns are associated with different clinician experience levels. However, a substantial amount of opioids are still given overall on patient discharge regardless of the clinician experience. Educational interventions aimed at reducing the opioid prescription rate and quantities may be considered for clinicians of all training levels.