The goals of patient evaluation, are to assess the likely cause of the erectile dysfunction and identify medical or psychologic conditions that may be contributing to the dysfunction or that may influence treatment options.

Often one can get an excellent clue to the etiology by the history and physical examination which can then be tested by precise laboratory tests. At the same time, some have multiple causes, such as a person with diabetes who is also on certain antihypertensive medications.
It is essential to see that the evaluation is comprehensive without having a "Test…because a test is available!" approach.

History and Clinical Examination
Anatomic, psychogenic, endocrinologic, neurologic, and vascular abnormalities may all contribute to impotence. Therefore, the evaluation of impotence begins with a comprehensive history and physical examination.

A thorough history is the most important factor in the evaluation of the patient with erectile dysfunction. The initial step is to identify the patient's concern with his sexual function. A careful sexual history and knowledge of concurrent illnesses and medications are essential. The sexual history should include the duration of impotence, level of libido, and a complete inventory of sexual partners. The sexual history is often the most helpful piece of information in directing further evaluation and treatment.
 

Psychogenic disorders may occasionally be primary factors contributing to erectile dysfunction. In order to improve treatment for patients with psychogenic impotence, Lue has suggested classifying psychogenic impotence into 5 broad categories:

Once a concern with the patient's sexual function is identified, the next step is to differentiate erectile dysfunction from other sexual problems, such as loss of libido or ejaculatory problems. The physician should use appropriate vocabulary, avoiding slang or excessively technical terminology. Having the patient define the terms in his own words will help the physician and patient communicate more effectively. The International Index of Erectile Function (IIEF) is a valuable tool for defining the area of sexual dysfunction. The IIEF is designed to be a self-administered measure of erectile dysfunction, but it also assesses a patient's function in other phases of sexual function. The IIEF also establishes a reliable baseline that can be used to monitor changes related to treatment.

The full 15 question IIEF which helps in distinguishing what type of sexual dysfunction is present can be accessed here.

The shortened 5 question IIEF which helps in judging the severity of true erectile dysfunction can be accessed here.

Early recognition of psychogenic disturbances allows the physician to avoid costly and confusing evaluation for other etiologies of impotence. Moreover, many patients complain of erectile dysfunction when they mean something lese such as premature ejaculation etc., and again this needs to be recognized before embarking on the detailed evaluation.

Because impotence is known to be associated with many common medical conditions and medications, a careful medical history may yield insights into the etiology of impotence. A history of peripheral vascular disease, coronary artery disease, diabetes, renal failure, tobacco and/or alcohol use, or psychogenic, neurologic, or other chronic debilitating diseases is often very helpful in directing further evaluation and treatment. Many common medications such as psychotropic drugs and antihypertensives have been associated with impotence. Similarly, a patient's surgical history may also provide clues to the possible causes of impotence. Prior radical pelvic surgery (eg, prostatectomy, abdominoperineal resection), radiation, and pelvic trauma are known to be associated with impotence.

Physical Examination
The physical examination should assess the patient's overall health. Particular attention should be given to the cardiovascular, neurologic and genitourinary systems, as these systems are directly involved with erectile function.

Careful physical examination with particular attention to sexual and genital development may occasionally reveal an obvious cause of impotence. Careful examination of the penis may reveal an anatomic abnormality such as a micropenis, the presence of chordee, or a Peyronie's plaque. The finding of small, soft, atrophic testes (the typical adult testis is 4.5 cm long with a range of 3.5 to 5 cm.) or gynecomastia should prompt an endocrine evaluation for hypogonadism (beard, body hair and voice should be evaluated for signs of hypogonadism) or hyperprolactinemia. Certain genetic syndromes such as Kallmann's or Klinefelter's syndrome may present with obvious physical signs of hypogonadism or distinctive body habitus. The prostate gland should be assessed for size, consistency and symmetry.

A careful neurologic examination should also be performed on all patients. Patients with diabetes or neurodegenerative disorders may show evidence of peripheral neuropathy. Several reflexes can be tested to evaluate sacral cord function. The superficial anal reflex, indicative of normal somatic function of sacral cord levels S24, is assessed by touching the perianal skin and noting contraction of the external anal sphincter muscles. The bulbocavernosus reflex also demonstrates normal sacral cord function. It is performed by placing a finger in the rectum and noting contraction of the anal sphincter and bulbocavernosus muscle when the glans penis is squeezed. External anal sphincter tone can be assessed during this maneuver as well.