TURBT according to Cleveland Clinic (like Mayo Clinic) has great medical explanations. Here's the link-https://my.clevelandclinic.org/health/procedures/turbt ; and here's an excerpt:
"What is transurethral resection of bladder tumor (TURBT)?
Transurethral resection of bladder tumor (TURBT) is a procedure that healthcare providers use to diagnose and treat bladder cancer at the same time.

During TURBT, a provider uses a long, thin tool with a camera on it (cystoscope) to find the tumor in your bladder and cut it out (resect it). Your provider sends the tumor to a lab where a pathologist will examine it. This helps determine its stage (how far it’s grown into your bladder wall) and grade (how different the cells look from normal cells).

Your provider doesn’t need to make any incisions for TURBT — the scope goes through your urethra (the tube that your pee travels through to get out of your body) to reach your bladder.

Why is TURBT done?
Providers perform TURBT when you have a tumor in your bladder that they need to biopsy and/or remove. It allows your provider to use just a single procedure to both remove and biopsy (take tissue samples from) the tumor."