Oliguria: Causes and Effects of Decreased Urine Output

6. Post-Renal Kidney Failure

In post-renal kidney failure, oliguria happens because the body cannot eliminate urine properly. In this case, the kidneys can produce the waste product, but a blockage prevents it from leaving the body, decreasing urine output. Causes of post-renal kidney failure include bladder, prostate, colon, or cervical cancer, kidney stones, or blood clots in the urethra. Urine that cannot be excreted can back up into the kidneys and cause infection and significant kidney damage.