Stones of the urinary tract (kidney, ureters and bladder) are a very common condition affecting up to 12% of the US population. Stones occur in both men and women of all ages; however, they most commonly occur in Caucasian males between 45 and 55 years. Children may also get kidney stones but it is not common.

Anatomy

• The kidneys are a pair of bean shaped reddish-brown organs that lie on either side of the spinal column and just below the diaphragm. They are about 5 inches (12.5 cm.) long and 3 inches (7.5 cm.) wide (Figures 1and 2 )
  
  1. Urine is produced in the kidneys and travels down through the ureters to enter the bladder
  2. On the medial (facing the spine) border the kidney is notched at the hilus, the point where the major artery to the kidney enters and vein leaves
  3. The ureter also leaves from the hilus
  4. The kidney is made up of over a million renal tubules (nephrons). All the nephrons together form the cortex. The nephrons filter the blood of waste products that pass into the urine
  5. The urine passes from the nephrons into collecting tubes called calyxes and then into the renal pelvis (the dilated upper portion of the ureter) and into the ureter, which conducts the urine into the urinary bladder
  6. A capsule of thin tissue encloses each kidney
  7. The bladder is located in the pelvis. It is held in place by ligaments and can be felt in the lower abdomen when full
• The urinary bladder is a hollow muscular organ that serves as a reservoir of urine. Normally the bladder can hold 250 - 450 cc (8 - 15 ounces) of urine
  1. The urethra is located at the base (lowest part) of the bladder and drains the urine out of the bladder. In women the outlet of the urethra can be seen just in front of the vagina. In men the urethra lies within the penis
  2. In males, the bladder has the prostate gland below (through which the urethra passes). In females, the uterus and the vagina lie behind the bladder

Figure 1 - Anatomy of the kidney. The upper portion of the kidney is cut away to expose the cortex, calyxes and renal pelvis. The renal artery and ureter enter and the renal vein leaves the kidney at the hilus. The adrenal gland rests on the upper pole of the kidney. © N. Gordon	Figure 2 - On the left side are seen the kidney and adrenal glands along with the ureter extending from the kidney to the bladder. On the right side are seen a staghorn stone in the kidney pelvis as well as stones in the ureter, bladder and urethra.© C. McKee