PATIENT HISTORY
Medical and sexual histories help define the degree and nature of ED. A medical history can disclose diseases that lead to ED, while a simple recounting of sexual activity might distinguish among problems with sexual desire, erection, ejaculation, or orgasm. Using certain prescription or illegal drugs can suggest a chemical cause, since drug effects account for 25 percent of ED cases. Cutting back on or substituting certain medications can often alleviate the problem.
PHYSICAL EXAMINATION
A physical examination can give clues to systemic problems. For example, if the penis is not sensitive to touching, a problem in the nervous system may be the cause. Abnormal secondary sex characteristics, such as hair pattern or breast enlargement, can point to hormonal problems, which would mean that the endocrine system is involved. The examiner might discover a circulatory problem by observing decreased pulses in the wrist or ankles. And unusual characteristics of the penis itself could suggest the source of the problem—for example, a penis that bends or curves when erect could be the result of Peyronie's disease.
LABORATORY TESTS
Several laboratory tests can help diagnose ED. Tests for systemic diseases include blood counts, urinalysis, lipid profile, and measurements of creatinine and liver enzymes. Measuring the amount of free testosterone in the blood can yield information about problems with the endocrine system and is indicated especially in patients with decreased sexual desire.
OTHER TESTS
Nocturnal Penile Tumescence (NPT) Test
Nocturnal erections occur in healthy males of all ages. Eighty percent of these happen during REM sleep. The average man has three to five episodes of NPT per night, lasing for 30 to 60 minutes each. With age, total nocturnal erection time decreases.
There are a variety of methods available for monitoring NPT. The monitoring is generally conducted with a simple outpatient device, rather than in NPT sleep labs. These devices electronically record the number, duration, rigidity and circumference of penile erections.
Monitoring erections that occur during sleep (nocturnal penile tumescence) can help rule out certain psychological causes of ED. Healthy men have involuntary erections during sleep. If nocturnal erections do not occur, then ED is likely to have a physical rather than psychological cause. Tests of nocturnal erections are not completely reliable, however. Scientists have not standardized such tests and have not determined when they should be applied for best results.
The goal of neuro-urologic testing is to uncover neurologic disease, such as diabetes mellitus or pelvic injury, or diagnose reversible neurologic conditions, such as nerve damage caused by long-distance bicycling. These tests also help determine whether a referral to a neurologist is necessary. The most commonly used tests include :
Combined Intracavernous Injection and Stimulation (CIS) Test -- This is the simplest, and most commonly used test for evaluating and diagnosing ED. It uses penile injections, visual or manual sexual stimulation and a subsequent erection.
Color Doppler Ultrasound -- This test uses harmless, non-invasive sound waves to produce a picture of the penile arteries, which enables experts to evaluate the arteries' functions.
Pharmacologic Cavernosometry and Cavernosography -- These tests evaluate penile veins and help identify any venous leakages.
PSYCHOSOCIAL EXAMINATION
Psychological conditions, such as performance anxiety, a strained relationship, lack of sexual arousability and mental health disorders, including depression and schizophrenia, may cause erectile dysfunction. Therefore, your doctor may recommend an interview with a psychologist that focuses on current sexual problems, partner relationship and any psychiatric symptoms you may be experiencing.