Final answer:
Painless hematuria in adults is most commonly caused by kidney stones, urinary tract infections, and to a lesser extent, urological cancers. Kidney stones can lead to blood in the urine once they cause damage to the urinary tract. Diagnostic tests are important to determine the exact cause of hematuria.
Step-by-step explanation:
The most common cause of painless hematuria in adults is often attributed to urinary tract infections (UTIs), kidney stones, and in some cases, urological cancers. Among these, kidney stones are particularly noteworthy, as they can cause blood in the urine when they cause minor damage to the inside wall of the kidney, ureter, or urethra. Kidney stones can vary in size and may pass through the urine without causing pain, but when they are large enough to cause an obstruction, this can lead to noticeable symptoms including hematuria.
Another significant cause could be glomerulonephritis, which is an inflammation of the glomeruli of the kidneys. The glomeruli act as filters, and when they are damaged, this can lead to blood cells leaking into the urine. Urinary tract infections can also present with hematuria; however, the presence of infection is often associated with symptomatic complaints such as pain or a burning sensation during urination.
It is important to conduct further diagnostic tests like urinalysis, imaging, or cystoscopy depending on the individual's symptoms and clinical history to determine the exact cause of hematuria.