Erectile Dysfunction (ED)

Erectile dysfunction (ED) is a medical term that describes the inability to achieve and or maintain an erect penis adequate for sexual function. This condition is one of the most common sexual problems for men. The number of men suffering from ED increases with age. Approximately 25 million American men suffer from ED, although not all men are equally distressed by the problem.

Dr. Lewis Harpster MD discussed urinary incontinence and erectile dysfunction at a recent educational seminar. Click here to watch the post-seminar interview.

Normal Function

Achieving a normal erection is a complex process involving psychological and sensory impulses that are transmitted by the brain, through the spinal cord, and ultimately to the penis. There, those impulses result in dilatation of penile vascular tissue and subsequently an erection. This process requires a normally functioning nervous system, adequate and healthy vascular tissue within the penis, and the male hormone testosterone. During erection the sum of these processes is to cause increased blood flow into, and decreased blood flow out of, the penis. Under these conditions the specialized vascular tissues of the penis (the paired corpora cavernosa) become engorged with blood causing the penis to become and rigid and erect. Eventually, these conditions revert to the resting state of low blood flow into, and increased blood flow out of, the penis. This process, called detumescence, returns the penis to a flaccid state. Any conditions that impact adversely on these events can lead to erectile dysfunction. Diabetes mellitus, high blood pressure, high cholesterol, cigarette smoking, peripheral vascular disease, and Peyronie’s disease are some of the more common health problems that can damage penile neurovascular tissues and result in ED. Low testosterone levels can impact adversely on libido and erectile function. Finally, certain medications, particularly anti-hypertensives, are known to contribute to ED.

Risk Factors

There are several risk factors for the development of ED. As men age, the level of circulating testosterone decreases. This may interfere with normal erection. While a low testosterone level itself is rarely the cause of ED (5 percent or less), low testosterone can be an additional contributing factor in many men who have other risk factors for ED. Low levels of sexual desire, lack of energy, mood disturbances and depression can all be symptoms of low testosterone. A simple blood test can determine if the testosterone level is abnormally low, and testosterone can be replaced using a number of different delivery systems (injections, skin patches, transdermal gels, subcutaneous implant).


Among the most common causes of ED are high blood pressure, diabetes mellitus, high cholesterol, cigarette smoking, and cardiovascular disease. Acting over time these diseases can lead to a degeneration of the penile blood vessels causing restricted penile blood flow during erection. This manifests as an inability to achieve and maintain a full erection, and may progress to complete loss of erections over time.

Therapeutic interventions used to manage a variety of medical conditions can interfere with normal erections. Patients undergoing pelvic surgery or radiation therapy for cancer of the prostate, bladder, colon or rectum are at risk for the development of ED. Antihypertensive medications, by lowering blood pressure throughout the body, can adversely affect penile blood flow during tumescence. Low testosterone, which occurs routinely in the treatment of certain forms of prostate cancer, results in ED in the majority of patients.


For most patients, the diagnosis will require a simple medical history, physical examination, and routine blood tests to rule out any previously undiagnosed medical conditions that may be causing ED. Blood glucose, hemoglobin A1c, cholesterol, triglycerides, basic metabolic panel, testosterone, and PSA would be comprehensive. Many times these tests have already been done in the context of previous doctor visits and may not need to be repeated. Most patients will not require extensive testing before beginning therapy.

Non-Surgical Therapy

Generally the first line therapy for uncomplicated ED is the use of oral medications known as phosphodiesterase-5 (PDE-5) inhibitors. Taken an hour or so before beginning sexual activity, these drugs boost the natural neurovascular signals being received by the penis during foreplay and during sex itself, thereby improving rigidity as well as prolonging the duration of the erection. These medications are safe and relatively effective with improvement in erection in up to 70 percent of patients who use them. The most common side effects are headache, stuffy nose, facial flushing, and muscle aches. Patients actively using nitroglycerin, or any nitrate containing medication, cannot take PDE-5 inhibitors due to the potential for life threatening hypotension.

An alternative to oral agents, intraurethral suppository entails the insertion of medication into the urethral prior to sex. The medication is capable of directly dilating penile blood vessels leading to erection. When effective, erection typically occurs within just a few minutes. This delivery system relies on the diffusion of the medication from the urethra (where it is inactive) into the nearby erectile bodies. Success rates are about 50 percent. The most common side effect is mild penile aching.

The most potent and direct delivery of vasoactive medication to the erectile tissue is achieved by direct injection. Termed intracorporal injection therapy, or simply penile injection therapy, this process involves injecting medication directly into the shaft of the penis prior to sex. Erection occurs immediately. The medications used for intracorporal injection therapy are potent vasodilators, and the effective dose for individual patients is unpredictable. Careful dose titration is necessary to achieve optimal results and to prevent priapism, a potentially dangerous prolonged and painful erection. Successful results can be achieved in 80 percent of patients.

An erection can be achieved mechanically in some patients through the use of a vacuum erection device (VED). This device combines a plastic cylinder or tube that slips over the penis, making a seal with the skin of the body. A pump on the opposite end of the cylinder creates a low-pressure vacuum within the cylinder and blood is mechanically drawn into the erectile tissue, resulting in an erection. To maintain the erection after the cylinder is removed, a rubber constriction band must be placed around the base of the penis. When the band is removed, the penis returns to a flaccid state. Success rates are variable.

Surgical Therapy

Placement of an inflatable penile prosthesis (IPP) can provide a permanent solution to erectile dysfunction in appropriate patients. The placement of a penile prosthesis involves surgically replacing the erectile tissue of the paired corporal bodies with two inflatable cylinders. These are attached to a small reservoir of fluid which is hidden deep in the pelvis, and to a pump which is placed in the scrotum. The surgery takes 2 hours and patients are admitted to the hospital for 23 hours. Following discharge a healing period of 4-6 weeks is necessary before the device can be used.

The device functions by a simple transfer of fluid between the reservoir and the penile cylinders. In the flaccid state, fluid is held in the reservoir. By mechanically pumping the scrotal pump fluid is transferred from the reservoir to the cylinders and the penis becomes erect. The penis will remain erect for as long as desired. When the erection is no longer necessary, a release mechanism on the pump is activated and the fluid now transfers from the cylinders back to the reservoir resulting in detumescence.

Satisfaction rates for penile prosthesis of 90 percent are among the highest for both patients and partners. As with any surgery, there are risks. Infection rates are low at < 5 percent, however, an infection can be devastating and will likely require removal of the entire apparatus. The majority of device infections occur within the early postoperative period. Patients routinely receive intravenous antibiotics at the time of surgery, during their 23 hour stay, and are sent home on an additional 5 days of oral antibiotics. Device failure can occur with rates of about 10 percent at 10 years. A nonfunctional device can be replaced by repeating the surgical procedure; however, a nonfunctional device poses no risk to the patient and can be left as is.

After Treatment

All nonsurgical therapies for ED compensate for but cannot correct the underlying problem that led to the ED. Because the medications used for treating ED cannot reverse the underlying cause, the effectiveness of nonsurgical therapy may diminish over time. Therefor it is important to follow-up with your doctor and report on the success of your treatment. If your goals are not being reached, if your erection is not of sufficient quality or duration and you are still distressed, you should explore alternatives with your doctor.


Click here to view Dr. Harpster's presentation on Managing Erectile Dysfunction.