There are several ways that erectile dysfunction is analyzed:
1) Obtaining full erections at some times, such as when asleep (when the mind and psychological issues, if any, are less present), tends to suggest the physical structures are functionally working.
However, the opposite case, a lack of nocturnal erections, does not imply the opposite, since a significant proportion of sexually functional men do not routinely get nocturnal erections or wet dreams.
2) Obtaining erections which are either not rigid or full (lazy erection), or are lost more rapidly than would be expected (often before or during penetration), can be a sign of a failure of the mechanism which keeps blood held in the penis, and may signify an underlying clinical condition, often cardiovascular in origin.
3) Other factors leading to erectile dysfunction are diabetes mellitus (causing neuropathy) or hypogonadism (decreased testosterone levels due to disease affecting the testicles or the pituitary gland).
Erection problems are very common. The Sexual Dysfunction Association estimates that 1 in 10 men in the UK have recurring problems with their erections at some point in their life.
Some blood tests are generally done to exclude underlying disease, such as diabetes, hypogonadism and prolactinoma.
Impotence is also related to generally poor physical health, poor dietary habits, obesity, and most specifically cardiovascular disease such as coronary artery disease and peripheral vascular disease.
A useful and simple way to distinguish between physiological and psychological impotence is to determine whether the patient ever has an erection.
If never, the problem is likely to be physiological; if sometimes (however rarely), it could be physiological or psychological. The current diagnostic and statistical manual of mental diseases (DSM-IV) has included a listing for impotence.
Clinical Tests Used to Diagnose ED
- Duplex ultrasound
- Duplex ultrasound is used to evaluate blood flow, venous leak, signs of atherosclerosis, and scarring or calcification of erectile tissue. Injecting prostaglandin, a hormone-like stimulator produced in the body, induces erection. Ultrasound is then used to see vascular dilation and measure penile blood pressure. Measurements are compared to those taken when the penis is flaccid.
- Penile nerves function
- Tests such as the bulbocavernosus reflex test are used to determine if there is sufficient nerve sensation in the penis. The physician squeezes the glans (head) of the penis, which immediately causes the anus to contract if nerve function is normal. A physician measures the latency between squeeze and contraction by observing the anal sphincter or by feeling it with a gloved finger inserted past the anus. Specific nerve tests are used in patients with suspected nerve damage as a result of diabetes or nerve disease.
- Nocturnal penile tumescence (NPT)
- It is normal for a man to have five to six erections during sleep, especially during rapid eye movement (REM). Their absence may indicate a problem with nerve function or blood supply in the penis. There are two methods for measuring changes in penile rigidity and circumference during nocturnal erection: snap gauge and strain gauge. (It should be noted that a significant proportion of men who have no sexual dysfunction nonetheless do not have regular nocturnal erections. Thus presence of NPT tends to signify physically functional systems, but absence of NPT may be ambiguous and not rule out either cause.)
- Penile biothesiometry
- This test uses electromagnetic vibration to evaluate sensitivity and nerve function in the glans and shaft of the penis. A decreased perception of vibration may indicate nerve damage in the pelvic area, which can lead to impotence.
- Penile Angiogram
- Invasive test - allows visualization of the circulation in the penis and is used during the repair of a priapism.
- Dynamic Infusion Cavernosometry
- (Abbreviated DICC) technique in which fluid is pumped into the penis at a known rate and pressure. It gives a measurement of the vascular pressure in the corpus cavernosum during an erection. To do this test, a vasodilator like prostaglandin E-1 is injected to measure the rate of infusion required to get a rigid erection and to help find how severe the venous leak is.
- Corpus Cavernosometry
- Cavernosography measurement of the vascular pressure in the corpus cavernosum. Saline is infused under pressure into the corpus cavernosum with utterfly needle, and the flow rate needed to maintain an erection indicates the degree of venous leakage. The leaking veins responsible may be visualised by infusing a mixture of saline and x ray contrast medium and performing a cavernosogram.
- Digital Subtraction Angiography
- In DSA, the images are acquired digitally. The computer creates a mask from lower-contrast x-rays of the same area and digitally isolates the blood vessels (this is done manually through darkroom masking with traditional angiography).
- Magnetic resonance angiography (MRA)
- This is similar to magnetic resonance imaging. Magnetic resonance angiography uses magnetic fields and radio waves to provide detailed images of the blood vessels. Doctors may inject a "contrast agent" into the patient's bloodstream that causes vascular tissues to stand out against other tissues. The contrast agent provides for enhanced information regarding blood supply and vascular anomalies. Aside from the IV used to introduce the contrast material into the bloodstream, magnetic resonance angiography is noninvasive and painless.
