Relief of urinary tract obstruction in tuberculosis to improve renal function. Analysis of predictive factors

To assess the effect of the relief of obstruction on the ultimate function of the affected renal unit in urinary tuberculosis, and to identify predictors of functional recoverability.

Of a total of 82 patients with urinary tuberculosis presenting over 7 years, 38 with evidence of upper tract obstruction were analysed. All patients were assessed with pre-operative excretory urography, urinary mycobacterial cultures and serum chemistry. Patients with subnormally functioning kidneys were assessed with baseline renal scans. Preliminary intervention in the form of JJ stenting or percutaneous nephrostomy (PCN) was carried out in patients with reasonable renal function. Function was reassessed after 4 weeks to detect evidence of improvement and factors which could affect the outcome were determined.

Thirty-eight patients had documented upper tract obstruction, of whom six had bilateral obstruction (total of 44 renal units). Ten renal units were not functioning at presentation, with a mean (SD) glomerular filtration rate (GFR) of 3.0 (5.73) mL/min, and no preliminary intervention was performed. In the remaining 34, preliminary intervention was carried out before definitive surgery (JJ stenting in 14, PCN in 15 and PCN followed by antegrade JJ stenting in five); 21 of these renal units were salvaged but 13 were lost despite overcoming the obstruction. Three of the 13 units deteriorated from having acceptable pre-treatment GFRs to becoming non-functional. Good renal cortical thickness, a low grade of renal involvement (Semb 1 or 2), the presence of more distal disease in the form of ureteric stricture and a GFR of > 15 mL/min were good predictors of renal recovery after diversion.

The loss of some renal units seems inevitable in patients with urinary tuberculosis, despite advances in chemotherapy. Having pre-operative predictors of renal recovery may ensure optimal patient selection, thereby reducing the number of procedures and economic burden on the patient who does not require intervention.