urology, medical specialty involving thediagnosis andtreatment of diseases and disorders of the urinary tract and of the male reproductive organs. (The urinary tract consists of the kidneys, the bladder, the ureters, and the urethra.)

The modern specialty derives directly from themedievallithologists, who were itinerant healers specializing in the surgical removal of bladder stones. In 1588 the Spanish surgeonFrancisco Diaz wrote the firsttreatises on diseases of the bladder, kidneys, and urethra; he is generally regarded as the founder of modern urology. Most modern urologic procedures developed during the 19th century. At that time flexible catheters were developed for examining and draining the bladder, and in 1877 the German urologistMax Nitze developed thecystoscope. The cystoscope is a tubelike viewing instrument equipped with an electric light on its end. By introducing the instrument through theurethra, the urologist is able to view the interior of the bladder. The first decades of the early 20th centurywitnessed the introduction of various X-ray techniques that have proved extremely useful in diagnosing disorders of the urinary tract. Urologicsurgery was largely confined to the removal of bladder stones until the German surgeonGustav Simon in 1869 demonstrated that human patients could survive the removal of onekidney, provided the remaining kidney was healthy.

Most of the modern urologist’s patients are male, for two reasons: (1) the urinary tract in females may be treated by gynecologists, and (2) much of the urologist’s work has to do with theprostate gland, which encircles the male urethra close to the juncture between the urethra and the bladder. The prostate gland is often the site of cancer; even more frequently, it enlarges in middle orold age andencroaches on the urethra, causing partial or complete obstruction of the flow of urine. The urologist treats prostate enlargement either by totally excising the prostate or by reaming a wider passageway through it. Urologists may also operate to remove stones that have formed in the urinary tract, and they may perform operations to remove cancers of the kidneys, bladder, and testicles.