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

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.

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.

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

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.

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.

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).

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.