Bladder infection, also known as cystitis, loosely termed as a UTI, is an indication for a trip to the doctor.
Common symptoms of bladder infection would be frequency and urgency associated with painful urination (also known as dysuria). In some cases, blood can be seen in the urine.
Having said that, these symptoms can also be caused by other conditions such as urinary tract stones and even growths (be it cancerous or non-cancerous) in the urinary tract.
If you have the symptoms mentioned above, you should seek medical attention.