Erectile Dysfunction

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Because erectile dysfunction is so complex, involving many different psychological and physical factors, your doctor may use several different tests to diagnose the condition and determine its cause. Only after your doctor determines the cause of ED can he or she effectively treat the condition.

First, your doctor will take a complete medical, personal, and sexual history. Next, he or she will most likely perform a thorough physical examination. If appropriate, a whole range of lab tests may be ordered to pinpoint the cause of the problem.

The history

First, the doctor will interview you about your personal and sexual history. Though some of these questions may feel intrusive, it is important that you answer honestly to aid in a proper diagnosis.

Questions may include:

  • What over-the-counter drugs, prescription medications, supplements, herbals, or illegal drugs are you currently using?
  • Have you experienced any psychological problems like stress, anxiety, or depression?
  • When did you first notice symptoms of erectile dysfunction?
  • What are the frequency, quality, and duration of any erections that you have had?
  • What are the specific circumstances under which ED first occurred?
  • Do you now, or did you ever, experience erections at night or during the morning?
  • What kind of sexual techniques do you use?
  • Are you experiencing any problems with your current relationship?
  • The doctor may also wish to interview your sexual partner, who may be able to offer insight about the underlying cause.

    Next, the doctor will take a complete medical history and perform a physical exam to assess whether the problem is caused by a medical condition.

    Lab tests

    If appropriate, your doctor may order one or more of the following diagnostic tests: 

    • Complete blood count (CBC). Your doctor can check for signs of underlying conditions such as anemia, a condition caused by a low red blood cell count that can cause fatigue, which in turn can cause ED.
    • Liver and kidney function test. These blood tests may indicate whether problems with your kidneys or liver are causing your erectile dysfunction.
    • Lipid profile. This test measures the level of lipids (fats) such as cholesterol in your blood. High levels of certain lipids may indicate atherosclerosis, a condition in which arteries harden, which can affect blood circulation in the penis.
    • Thyroid function test. Thyroid problems may cause or contribute to erectile dysfunction.
    • Blood hormone studies. Blood hormone studies measure testosterone and/or prolactin levels to look for any abnormalities with these sex hormones. Blood LH and FSH levels evaluate the pituitary's role in regulating these hormones.
    • Urinalysis. Analysis of urine can provide information about protein and sugar in the urine. If present, these substances could indicate diabetes or kidney disease, which can cause erectile dysfunction.
    • Special diagnostic tests

      Beyond the common laboratory tests, other special diagnostic tests may be needed: 

      • Duplex ultrasound. This test uses high-frequency sound waves to make images of body tissues. Doctors can use the ultrasound to evaluate blood flow and check for signs of a venous leak, atherosclerosis, or tissue scarring. This test is performed while the penis is erect (usually induced by an injection of a drug that stimulates erection) and also while it is flaccid.
      • Bulbocavernosus reflex. This test evaluates nerve sensation in the penis. During the test, your doctor will squeeze the head of your penis, which should immediately cause your anus to contract. If nerve function is abnormal, there will be a delay in response time.
      • Nocturnal penile tumescence (NPT). This test measures a man's erectile function while he is sleeping. Normally, a man will have five or six erections during each night's sleep. The absence of these nighttime erections could indicate a problem with nerve function or circulation. Doctors perform the snap-gauge method of nocturnal penile tumescence by wrapping three plastic bands of varying strength around the penis. Erectile function is then measured based on which of the three bands break. The strain gauge method works by placing elastic bands around the tip and base of the penis. If the penis becomes erect during the night, the bands stretch, measuring the changes in penile circumference.
      • Penile biothesiometry. This test uses electromagnetic vibration to determine sensitivity and nerve function. A decreased sensitivity to these vibrations may indicate nerve damage.
      • Vasoactive injection. During this test, doctors produce an erection by injecting special solutions that cause the blood vessels to dilate, allowing blood to enter the penis.
      • Dynamic infusion cavernosometry. During this test, doctors can determine the severity of venous leak by pumping the penis full of fluid and measuring how much fluid is needed to keep a penis erect.
      • Cavernosography. Radiographic contrast is added to the fluid that's pumped into the penis during a dynamic infusion cavernosometry. X-rays that detect the contrast then show the location of a venous leak.
      • Arteriography. Doctors inject contrast into the artery of candidates for vascular reconstructive surgery, a technique that circumvents a blockage by transferring an artery from an abdominal muscle to the problem area. The contrast allows doctors to see the blocked blood vessels by X-ray.
      • Last reviewed on 08/13/2008

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