Erectile dysfunction is the inability to attain or maintain an erection of the penis that is firm enough for penetration during sexual intercourse.
The condition is also called impotence. To initiate and maintain an erection, the penis must fill with blood. Nerve signals stimulate this blood fill. The nerves prompt certain blood vessels in the penis to expand so blood can fill it. Meanwhile, other blood vessels constrict, trapping blood inside.
Male Genitourinary System
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The following factors can cause erectile dysfunction:
Veins are compressed when blood fills the penis. This will help trap the blood in the penis. If these veins are not fully compressed, then blood can leave the penis. The inability to keep blood in the penis will make it difficult to reach or keep an erection. The compression of the veins may not occur, or may be weaker than it should if the blood vessels that are supposed to fill do not fill enough. Blood vessels may not fill enough because of injury or disease.
Erection cannot be attained if nerve signals do not prompt blood vessels to do their job or if blood flow to the penis is reduced.
Nerve problems can also diminish feeling in the penis, resulting in impotence.
Many medications can cause erectile dysfunction by impairing either vascular or nerve function.
Medical conditions that can lead to neurovascular dysfunction include: Diabetes
—can interfere with nerve signals
Arteriosclerosis, also known as hardening of the arteries—can reduce blood flowPeripheral neuropathy
, spinal cord injury, and surgery—can affect nerve function
Psychological factors account for 10%-15% of erectile dysfunction cases. The brain initiates many of the nerve signals required for a successful erection. Problems in your relationship, feelings of guilt associated with sex,
, and stress can all lead to erectile dysfunction
An estimated 25-30 million US men have erectile dysfunction. Erectile dysfunction increases with age, affecting about 20% of men aged 20 and older and 78% of men aged 75 and older.
Erectile dysfunction. National Institute of Diabetes & Digestive & Kidney Diseases website. Available at:
http://kidney.niddk.nih.gov/kudiseases/pubs/ED/index.aspx. Updated November 2015. Accessed March 8, 2016.
Erectile dysfunction. Urology Care Foundation website. Available at:
http://www.urologyhealth.org/urologic-conditions/erectile-dysfunction. Accessed March 8, 2016.
Guay AT, Spark RF, et al. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of male sexual dysfunction: a couple’s problem. 2003 update.
Sivalingam S, Hashim H, et al. An overview of the diagnosis and treatment of erectile dysfunction.
Webber R. Erectile dysfunction.
Last reviewed March 2016 by Adrienne Carmack, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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