Final answer:
Kidney stones adhere to the renal pelvis and vary in size. Larger stones can obstruct the ureter, leading to severe pain and other symptoms like nausea and bloody urine.
Step-by-step explanation:
Kidney stones sometimes adhere to the walls of the renal pelvis, which is the area where urine collects before being passed down the ureter. They are mineral crystallizations that can form when substances like calcium, oxalate, and phosphorus become highly concentrated in the urine.
Kidney stones vary in size; smaller ones may pass through the urinary tract with minimal or no pain, while larger stones can cause severe pain and block the flow of urine. When they become large enough, kidney stones have the potential to cause obstruction of the ureter, leading to symptoms such as severe episodic pain, nausea, vomiting, and hematuria (bloody urine).