<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I believe I have priapism. My erection hasnt gone away for a few hours now, and its quite painful.  <response>: Im sorry to hear that. Based on your symptoms, I recommend that we do a few medical tests. Well need to run some hematologic tests, a complete blood count, and a urinalysis. Well also need to measure your urinary system and insert a catheter into your urinary bladder. Additionally, well have to do a prostate-specific antigen measurement. Finally, well need to replace your fluids through intravenous therapy. 