Clinics & Inpatient Care Units

Urology - Kidney Stone Centre

About Kidney Stones

Kidney stones begin when tiny crystal particles that are found in urine clump together within the kidney. Over time, these substances can become concentrated, and the crystals enlarge until they become stones.

Stones can travel down the ureter to the bladder and out of the body through the urethra (the urinary passage). Along the way, stones can become stuck and cause blockage of the kidney and severe pain. As they move, they can also cause blood to appear in the urine.
There are two narrow points in the ureters where stones can commonly become stuck: at the UPJ (near the kidney) and at the UVJ (near the bladder.)

Other factors besides the concentration of crystallizable substances suspended in urine also play a role in stone formation. For instance, the concentration of natural substances and the acidity (pH) of the urine are factors in the formation of stones.

Crossed, fused renal ectopia – sometimes one of the kidneys can cross to the wrong side during fetal development and fuse with the other kidney. This abnormality of development seldom causes any problems.

Kidney stones can also form if a kidney is partially blocked, as urine becomes stagnant in the kidney resulting in crystal and stone formation. Blockage of the kidney causes it to swell – a process called hydronephrosis that can be diagnosed by ultrasound or X-rays.

There are many other reasons for kidney stones to form, and many are listed on the risk factors page.