The most widely used, and most reliable method of measuring erectile dysfunction is simply to ask the patient a series of direct questions. The most widely used questions are known as the Index of Erectile Function (IIEF).
These questions were developed in 1996-1997 by Pfizer who needed a reliable method of measuring erectile function when conducting clinical research studies for sildenafil, which was launched with the brand name Viagra. The questionnaire asked questions about five different aspects of erectile function: penile hardness, orgasmic function, sexual desire, intercourse satisfaction, and overall sexual satisfaction.
They enlisted the help of an international panel of experts to refine and validate the International Index of Erectile Function (IIEF). The questionnaire has been linguistically validated in 32 languages and used as a primary endpoint in more than 50 clinical trials. It remains the gold standard for measuring erectile function.
Shorter questionnaires have been found to be more accurate and so a slimmed down version of the IIEF, consisting of just five questions is often used. This is known as the Sexual Health Inventory for Men or SHIM.
A “penile plethysmograph” is a device consisting of a collar connected to a recording device that measures the girth of the penis. It has been used in the research of subconscious responses to various types of pornography, although this approach has largely been discredited, earning it an entry in the Skeptic’s Dictionary. It is still useful in measuring nocturnal penile tumescence (NPT), which is whether the penis becomes hard at night. If it does, it indicates that a patient’s problems getting an erection are psychological rather than physical.
Doppler ultrasound can also be used to investigate the flow of blood in the penis and determine where blockages of the blood vessels is occurring. Problems with blood flow in the penis are an early indicator of endothelial dysfunction which can lead to atherosclerosis and cardiovascular problems.
Angiograms can be used to investigate patients who have blocked or damaged arteries and veins. Opaque dyes are injected into the bloodstream and then viewed with x-rays, CT or MRI scanners.