Impotence is a frustrating condition in which a man can’t get as erection or keep it long enough for sexual intercourse. It can be
a burden for the man and his partner. Erection problems are common and may be due to physical causes, psychological causes or both. But impotence is treatable .

Nocturnal Penile Tumescence (NPT) Testing:

This method is useful for select individuals. NPT testing takes advantage of the fact that men with normal erectile function have 4-6 episodes of involuntary, nocturnal erections lasting 20-50 minutes during a 6-8 hour sleep cycle. These erections occur mostly during REM (rapid eye mmovement) sleep. NPT testing in the diagnosis of ED has been described and is known worldwide. NPT is best used to distinguish between organic and psychogenic ED. 


Rigiscan monitor is used to monitor penile size and rigidity during any study. It is strapped around the thigh. One loop of the monitor is then placed around the participant's penis about 4 inch from its base. Another loop is placed around the end of the penis about 1⁄4 inch from the glans penis. The patient Lie down in a comfortable bed with a towel placed over his lap. Videos with neutral content followed by one with erotic content, and then another with neutral content, are successively presented. The erotic video includes explicit scenes of heterosexual activities such as vaginal intercourse, oral sex and manual stimulation. Erectile function is recorded during the videos,  

Color Duplex Doppler Study

Color Duplex Doppler ultrasonography (CDDU) is commonly used noninvasive screening procedure. It is superior to continuous
wave sonography as it allows clear visualisation of the deep cavernosal arterial tree. It is usually combined with
intracavernosal injection of vasodilators, and measurements of blood velocity are done before and after the injections of vasodilators. In flaccid state, the cavernosal artery can follow a tortuous course; but in erect state, it becomes straighter. The transducer is placed on the dorsal aspect of the penis mThe vasodilator drugs can be injected into any of the cavernous tissue at its distal third, as there is communication between two sides. There are various options (see intracavernosal penile injection therapy later in the chapter) that are used:

a. Papavarine 60 mg in 1 ml solution. (Can give false , negative result  )

b. Papaverine 40 mg with phenolamine 2.5 mg in 1 ml solution.(Is not available  )

c. Papaverine 4.4 mg, chlorpromazine with prostaglandin E-1 1.5 μg in 0.5 ml.

d. Sildenafil citrate – 50 mg (Can give false negative result  ) 

Normal values

PSV (Peak
systolic velocity)-30 cm/sec or more

(End-diastolic velocity) — 5 cm/sec or less

 AT (Acceleration time)-0.11 sec or less

(Resistive index) — 0.85 or more


Interpretation of results

Arteriogenic ED-

1. PSV <30 cm/sec

AT > 0.11 sec

Veno-occlusive ED

1. EDV >5 cm/sec

2. RI<0.85