Blood in the urine, also called hematuria, is serious. Whether it is an isolated incident or a recurring problem, you should see a doctor. It could be a sign of any of several serious health problems. If you ignore it, the condition may get worse.
Hematuria is not always obvious. The quantity of blood present in the urine can be enough to turn it red, brown, or pink (gross hematuria). It may also be so small it can only be detected during a urine test (microscopic hematuria).
Several health conditions can lead to hematuria. This article discusses the symptoms and potential causes of hematuria.