There are no formal tests to diagnose
erectile dysfunction (impotence).
Blood tests are generally done to
exclude underlying disease, such as
diabetes, hypogonadism and
prolactinoma.
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 is more likely to be
psychological.
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.
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.
Medicine
A few causes of impotence may be
iatrogenic (medically caused). Various
antihypertensives (medications intended
to control high blood pressure) and
some drugs that modify central nervous
system response may inhibit erection by
denying blood supply or by altering
nerve activity. Antidepressants,
especially SSRIs, can cause impotence
as a side effect. Surgical intervention
for a number of different conditions
may remove anatomical structures
necessary to erection, damage nerves,
or impair blood supply. Some studies
have shown that male circumcision may
result in an increased risk of
impotence, while others have found no
such effect, and another found the
opposite.
Excessive alcohol use has long been
recognised as one cause of impotence,
leading to the euphemism "brewer's
droop"; Shakespeare made light of this
phenomenon in Macbeth.