Because there are a variety of causes of erectile dysfunction, there are several different tests your doctor may use to diagnose the condition and determine its cause. Only after the cause of ED is determined can it be effectively treated.
Before ordering any tests, your doctor will review your medical history and perform a thorough physical exam. The doctor will also "interview" you about your personal and sexual history. Some of these questions will be very personal and may feel intrusive. However, it is important that you answer these questions honestly. The questions asked may include:
Thyroid function test: An overactive thyroid (hyperthyroidism) may contribute to ED by producing an excess of thyroid hormones. Thyroid hormones help regulate the levels of sex hormones, and a deficiency in these hormones may contribute to or cause ED.
Urinalysis: Analysis of urine can provide a wealth of information, including information on protein, sugar, and testosterone levels. Abnormal measurements of these substances can indicate diabetes, kidney disease, or a testosterone deficiency, all of which can contribute to ED.
Duplex ultrasound: An ultrasound uses high-frequency sound waves to take "pictures" of the body's tissues. For people with ED, an ultrasound may be used to evaluate blood flow and check for signs of a venous leak, atherosclerosis, or tissue scarring. This test is performed both while the penis is erect (usually induced by an injection of a drug that stimulates erection) and also while it is soft.
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 while asleep. A lack of these erections may indicate there is a problem with nerve function or circulation to the penis. The test can be performed using several different methods, including the snap gauge method and the strain gauge method. The snap gauge method is performed by wrapping three plastic bands of varying strength around the penis. Erectile function is then measured based on which of the three bands breaks. 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. Another method uses a RigiScan electronic device, where loops are placed around the tip and base of the penis, providing continuous monitoring of erectile events.
Penile biothesiometry: This test involves the use of electromagnetic vibration to determine sensitivity and nerve function. A decreased sensitivity to these vibrations may indicate nerve damage.
Vasoactive injection: During this test, an erection is produced by injecting special solutions that cause the blood vessels to dilate (enlarge), allowing blood to enter the penis.
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 rectum to contract. If nerve function is abnormal, there will be a delay in response time or absence of rectal contraction.
PSA: This test may be abnormal due to prostate cancer, enlargement, or infection. These conditions and their treatments may complicate ED.