How is ED diagnosed?

ED is diagnosed by an urologist or another medical professional and for most patients; the diagnosis will require a simple medical history, physical examination and a few routine blood tests.
Medical History exam requires health care providers to ask about you, and your ED experience.  The doctor will also want to know if you have any other conditions that might affect your ED, such an any endocrine problems or depression.  They may ask questions about your sexual history and performance, which may be very personal but necessary to understand the root cause of the problem.  The important thing to remember is not to be embarrassed while speaking with your physician and to be very open to allow for the best treatment options for you.  Other questions the physician is likely to ask are the following:
Your current sexual function
When you started noticing changes
Any past medical or sexual problems
Surgery or injury to the pelvic area
Current and past medication usage
Lifestyle and personal habits (i.e. smoking, drinking, use of illicit drugs, etc.)
Relationship with current and past partners

Physical Examinations means the doctor will check your overall health and physical condition.  They will look for signs of problems with your circulatory, nervous and endocrine system.  This includes checking your blood pressure, penis and testicles and you may need to have a rectal exam to check the prostate.  These tests are not painful and may provide valuable information about the cause of ED.  Most patients do not require extensive testing before beginning treatment.
The choice of testing and treatment depends on the goals of the individual. If erection returns with simple treatment like oral medication and the patient is satisfied, no further diagnosis and treatment are necessary. If the initial treatment response is inadequate or the patient is not satisfied, then further steps may be taken. In general, as more invasive treatment options are chosen, testing may become more complex.