How useful is ultrasound doppler for assessing erectile dysfunction?

Some erectile dysfunction (ED) clinics use a handheld doppler device to make an assessment of whether or not shockwave is viable for treating erectile dysfunction. However this assessment is done for theatrical reasons and the units are designed for use on the arms and legs and are not sensitive enough to find out anything meaningful about the nature of penile blood flow. 

In rare cases, it is useful for a urologist or qualified technician to conduct an ultrasound doppler diagnosis. They would employ a device with imaging capabilities, most often with a colour display, can diagnose vascular abnormalities including arterial insufficiency (poor blood supply), venous leakage (inability to maintain blood), or plaque buildup in the penile arteries.

In order for this assessment to be made it is necessary to track blood flow through a cycle of a flaccid penis becoming erect and then tumescent. For a patient with ED the erection has to be stimulated by injections of a prostaglandin into the erectile tissue at the base of the penis.

A hand held ultrasound doppler typically used for ascertaining blood flow issues in arms and legs

Why a hand held doppler unit cannot ascertain useful information about penile blood flow

The penis, contrary to how simple it looks, is a complex organ. An erection happens when the arteries in the penis relax causing an inflow of blood into the erectile tissue, which in turn constricts the veins that exit the penis. The arteries and veins in the penis run close to each other and the largest of them are small – in most men they are less than 2mm in diameter. 

Hand held doppler units which have audio or numeric output do not have the resolution to determine anything meaningful about the state of these blood vessels, nor about the condition of the erectile tissue itself. Therefore, without stimulating an erection with an injection, they are not useful for differentiating between the blood flow characteristic of a penis that is healthy and able to achieve a hard erection, and others where the patient is unable to get an erection adequate for sex, and certainly not to ascertain the potential efficacy of shockwaves for treating erectile dysfunction.

An additional reason why hand held doppler units cannot help ascertain the efficacy of shockwave for treating erectile dysfunction

Typically, around one-third to one-half of the total length of the erectile tissue is within the body (this part is known as the crura), with the remaining half to two-thirds extending into the shaft of the penis. The blood vessels in and around the crura run close to the main arteries and veins that travel to and from the legs. These vessels are relatively large. In most individuals they are 6 – 8 times larger than the major vessels that run to and from the penis. The doppler units cannot determine the blood flow in the penile vessels separately from the other major vessels and therefore aren’t useful in diagnosing the nature of erectile dysfunction and whether or not the patient will respond to various treatments.