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.
Classification: There are three physiologic narrowing of the ureter where stones may obstruct. The first narrowing of the ureter is the location where the renal pelvis of the kidney meets the ureter or the uretero-pelvic junction (UPJ).The next level of narrowing is where the ureter crosses the iliac vessels.he third ureteral narrowing exist where the intramural portion of the ureter meets the bladder known as the ureteral vesico-junction, or UVJ, which measures approximately 1 - 5 mm. in size.