Specialized diagnostic tests ED

Nocturnal penile tumescence and rigidity (NPTR)

The nocturnal penile tumescence and rigidity (NPTR) assessment should take place for at least two nights. 
The presence of an erectile event of at least 60% rigidity recorded on the tip of the penis, which lasts for 
10 minutes or more, should be considered as indicative of a functional erectile mechanism (24).

Intracavernous injection test

The intracavernous injection test offers limited information regarding vascular status. A positive test is defined
as a rigid erectile response (unable to bend the penis) that appears within 10 minutes after the intracavernous
injection and lasts for 30 minutes (25). Such a response may indicate a functional but not necessarily normal
erection, since an erection may coexist with arterial insufficiency or veno-occlusive dysfunction (26). Its clinical
implication is that the patients will respond to the intracavernous injection programme. In all other cases, the
test is inconclusive, and a duplex ultrasound of the penile arteries should be requested.

Duplex ultrasound of penile arteries

A peak systolic blood flow higher than 30 cm/sec and a resistance index higher than 0.8 are generally conside-
red to be normal (25). There is no need to continue vascular investigation when the duplex examination is normal.

Arteriography and dynamic infusion cavernosometry or cavernosography (DICC)

When it is abnormal, arteriography and dynamic infusion cavernosometry or cavernosography should be
performed only for patients who are considered potential candidates for vascular reconstructive surgery.

Psychiatric assessment

Patients with psychiatric disorders must be referred to a psychiatrist particularly interested in ED. For younger
patients (<40>

Penile abnormalities

Patients with ED due to penile abnormalities, such as hypospadias, congenital curvature, or Peyronie’s disease
with preserved rigidity, may require surgical correction with high success rates.