Where do kidney stones primarily form in the body?

Kidney stones primarily form in the kidney pelvis, which is the area where urine collects before it moves down to the ureters and into the bladder. The kidney pelvis is conducive to stone formation due to the concentration of minerals and substances in the urine that can crystallize and aggregate into stones. Factors such as dehydration, certain dietary habits, and metabolic disorders can increase the likelihood of stone formation in this region.

While stones can travel through the urinary tract and may be found in the bladder or urethra, these areas are typically not where they originate. The bladder can hold stones that have passed from the kidneys, and the urethra can be a site of obstruction if a stone gets lodged there, but these circumstances are secondary to the primary site of formation, which is the kidney pelvis.