When you hire an electrician, even for a small job like installing a light switch, be aware that most charge a minimum fee for a visit. But that fee will roll into the cost of the job. In other words, although an electrician may charge $70 just to walk in the door, that money might cover the first hour of work. The cost of the job will vary depending on the complexity and parts needed. One factor that often contributes to a job's complexity is access.
1 Kidney stones. Large kidney stones cannot enter the ureter but a stone less than 5mm in diameter can cause a sudden obstruction.  Blood clots may obstruct the ureter and this is usually seen with massive hematuria (blood in the urine). Bleeding in these cases may be due to tumors, papillary necrosis or kidney stones.
When stones block the urinary tract for a long time, urine backs up in the tubes inside the kidney, causing excessive pressure that can cause the kidney to swell (hydronephrosisâsee Hydronephrosis: A Distended Kidney) and eventually damage it.