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Further Testing

Following completion of a full interview, physical examination, and laboratory testing, your doctor should be able to determine the general type of dysfunction and the need for any additional testing. Such tests include penile or pelvic blood flow studies, nocturnal penile tumescence testing, penile biothesiometry (nerve testing), and/or more blood tests.

• Numerous devices have been developed to determine if erections occur during sleep. One such example is a snap gauge that is fastened around the penis and opens when an erection occurs.

• One of the most common tests used to evaluate penile function is the direct injection of PGE1 into the penis. PGE1, also called prostaglandin E1 or alprostadil, is a medication that increases blood flow into the penis and normally produces erections.
  
  
  • If the penile structure is normal or at least adequate, an erection should develop within several minutes. You and your doctor can judge the quality of the erection.
    
    
  • If successful, this test also establishes penile injections as one possible therapy. 
  
  
• Nocturnal penile tumescence or NPT testing may be useful in distinguishing between psychological causes and physical causes of erectile dysfunction.
  
  
  • This test involves the placement of a band around the penis that you would wear during 2 or 3 successive nights.
    
    
  • If an erection occurs, which is expected during rapid eye movement (REM) sleep, the force and the duration are measured on a graph. 
    
    
  • Inadequate or no erections during sleep suggest a physical (or organic) problem, while a normal result may indicate a possibility of emotional, psychological, or mental causes.
    
    
• Formal neurological testing is not needed for most men, and specialized nerve conduction studies are only performed in selected cases. However, anyone with a history of nervous system problems, such as loss of sensation in the arms or the legs and those with a history of diabetes, may be asked to undergo further neurological testing.
  
  
  • Measuring the sensitivity of the skin of the penis to detect vibrations (called biothesiometry) can be used as a simple office nerve function screening test.
    
    
  • This test involves the use of a small vibrating test probe placed on the right and left side of the penile shaft as well as on the head of the penis. The strength of the vibrations is increased until you can feel the probe vibrating.
    
    
  • Although this test does not directly measure the erectile nerves, it serves as a reasonable screening for possible sensory loss and is simple to perform.