Prognosis of radiologically non-functioning obstructed kidneys

Development and validation of a novel prediction model for predicting renal function recovery after diversion in patients with obstructive uropathy

OBJECTIVE

To develop and validate a novel prediction model predicting renal function recovery following diversion in patients with obstructive uropathy (OU) to the emergency department (ED).

METHODS

After a systematic literature search, a novel prediction model called PGIMER Obstructive Uropathy Score (POUS) was constructed including five variables: age (<60 or >60 years), duration of symptoms (<4 or >4 weeks), presence of solitary functioning kidney, baseline hemoglobin levels and venous blood pH. This model was then validated in a prospective, observational single-center study of patients presenting with OU caused by various etiologies. Patients with OU and raised serum creatinine (>2 mg/dL) presenting to our ED were included. Renal function recovery was defined as creatinine value <1.5 mg/dL at 4 weeks following diversion.

RESULTS

In this study, 174 consecutive patients with OU were recruited, and 74 (42.5%) patients had renal function recovery. All the variables included in the POUS were noted to be statistically significant on univariate analysis. On multivariate logistic regression analysis, only POUS was identified as an independent predictor of renal function recovery. On receiver operating curve analysis, the area under the curve for POUS was 0.832 for predicting recovery. A POUS of 5 or more had specificity and sensitivity of 83% and 73.6%, respectively, in predicting renal function recovery. The goodness of fit and calibration plots showed good concordance of the predicted values with the observed values.

CONCLUSIONS

The POUS model is an accurate and simple-to-use tool for predicting renal function recovery. POUS model requires external validation prior to clinical use in different populations.

Factors influencing recoverability of renal function after urinary diversion through percutaneous nephrostomy

CONTEXT

Various factors predict recoverability of kidney function preoperatively. Placement of percutaneous nephrostomy (PCN) and measuring the differential creatinine clearance (diff. %CrCl) is still regarded as a simple and reliable method.

AIMS

The aim was to evaluate correlation between renal cortical thickness (CT), hydronephrosis, intrapelvic pressure (IPP), PCN output, renal morphological factors such as length, width, echogenicity, corticomedullary differentiation (CMD), status of c/l kidney, and presence of infection which can predict recoverable function.

SETTINGS AND DESIGN

A prospective study done between July 2013 and June 2014 in Urology Department.

SUBJECTS AND METHODS

Hundred and sixty patients of supravesical obstruction for various causes who need PCN either due to chronic renal failure or nonvisualized kidney on contrast study, were included. IPP was measured during PCN placement. After 4 weeks 24 h urine was sent for CrCl and urine pH.

STATISTICAL ANALYSIS USED

Correlation of continuous and categorical variables with dependent variable (diff. %CrCl) was formulated using spearman correlation and Mann-Whitney U test. Simple and multiple linear regression analysis were performed.

RESULTS

The study includes 160 patients with median age of 65.5 years. Hydronephrosis were due to stone in 76 (47.5%), pelviureteric junction obstruction (PUJO) in 40 (25%), cancer in 32 (20%), others in 12 cases (7.5%). IPP was <10 cm H2O in 48 (30%); 10-20 cm H2O in 64 (40%) and >20 cm H2O in 48 (30%). There was significant correlation between IPP and diff. %CrCl with correlation coefficient ρ = 0.509 (P = 0.0001).

CONCLUSIONS

CT, parenchymal echogenicity, CMD, pre-PCN creatinine, and status of c/l kidney are the only independent variables which can predict the renal function while other variables like renal size, urine output, infection, hydronephrosis lost their statistical significance in multivariate analysis. Furthermore, IPP measured before PCN directly correlated with daily urine output and diff. %CrCl.

Role of ureteric stents in relieving obstruction in patients with obstructive uropathy

Purpose:

The aim of this study is to evaluate the role of ureteric stents in relieving obstruction and improvement of kidney function in patients with obstructive uropathy.

Materials and Methods:

This study involved 138 patients with obstructive uropathy with age ranged from 2 months to 73 years. Patients classified into two groups: Group (I): Includes 57 patients (41.3%), ureteric stents fixed to them; and Group (II): Includes 81 patients (58.6%) managed by other treatment modalities. All patients underwent clinical assessment, Laboratory and radiologic investigations: At presentation and postoperative. These included: Complete urine analysis, urine culture and sensitivity, serum creatinine, serum urea nitrogen, serum uric acid, serum sodium (Na), serum potassium (K), Fasting blood glucose level and blood picture and plain X-ray (KUB), abdominal ultrasonography (US), diuretic renography and retrograde pyelography.

Results:

Renal glomerular filtration rate (GFR) was used as an indicator for improvement of renal function after fixation of ureteric stent. In group I: 56 (71.8%) kidneys showed significant recovery compared to 61 kidneys (66.3%). In group II, there is statistically significant relation between renal perfusion and renal recovery (P < 0.004), statistically significant relation between parenchymal thickness and recovery in both groups (P < 0.0002), statistically significant relation between degree of corticomedullary differentiation and recovery (P < 0.0003) and statistically significant relationship between hemoglobin levels at presentation and the recoverability (P < 0.002).

Conclusion:

The predictors of renal recoverability revealed that ureteral stents alone can help in regaining renal function and significant improvement of clinical condition in patients with obstructive uropathy.