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Table of Contents
The British Association of Urological Surgeons defines erectile dysfunction (ED) as “an inability to obtain or maintain an erection sufficient for penetration and for the satisfaction of both sexual partners.”1 Frequently termed impotence, the global prevalence of ED is estimated to be between 13.1% and 71.2%.2 Measurements vary by continent; however in all cases, increasing age is a risk factor for acquiring the condition.2 Untreated, ED can lead to an increased risk of cardiovascular (CV) disease while similarly, a finding of ED may be a red herring for a patient’s undiagnosed CV disease.3 However, patients may be hesitant to discuss ED concerns with a healthcare provider (HCP) due to embarrassment or misconceptions about the condition.4,5 Therefore, it is essential for HCPs to remain vigilant about screening those with suspected ED, for timely intervention to prevent future health consequences.6
Anatomy of the Penis
The penis is an organ of the male reproductive system, with associated musculature, blood supply, drainage and innervation (Figure 1). From proximal to distal, the penis is structured into the root, the main body and the glans/tip of the penis. Anchored at the root, are three bodies of erectile tissues: right and left corpus cavernosa and central corpus spongiosum. These tissues span the entire length of the penis and fill with blood upon sexual arousal. Four muscles work in tandem with this process to maintain erection and empty the urethra: bulbospongiosus (x2) and ischiocavernosus (x2). Surrounding the erectile tissues and muscles are three layers of fascial coverings- Dartos fascia, Buck’s fascia and Tunica albuginea– which serve to protect and support internal structures.
The penis is supplied by the dorsal penile artery, the deep penile artery and the bulbourethral artery, all which are derived from the internal pudendal artery. Venous drainage is via the superficial and deep dorsal veins to the superficial external pudendal vein and prostatic venous plexus, respectively. All penile innervation comes from S2-S4 spinal cord segments. Sympathetic penile innervation is provided by the pudendal nerve, which gives off the dorsal nerve of the penis, whereas parasympathetic innervation is from the prostatic nerve plexus which gives rise to the cavernous nerves.
Causes of ED
The cause of ED is frequently multifactorial, with mixed organic and psychogenic origins.8 For simplicity, it is best to broadly categorize the aetiology of ED into the following categories:
Table 1. The Causes of Erectile Dysfunction
CAUSES OF ED
Resulting from penile arterial insufficiency, ↑ BP or stenotic lesions
Sexual function declines as part of normal ageing; ↑ latent period, ↓ ejaculation, ↑ refractory period
Iatrogenic trauma from pelvic surgery (i.e. prostatectomy, cystectomy)
*Extensive bicycle riding has been implicated in the development of ED
Resulting from performance anxiety, strained relationships, lack of sexual arousal. Also linked to depression and schizophrenia.9,10
Situational (i.e. happens with a partner, but not with masturbation)
*Normal nocturnal erections are present
Note: Ascertaining whether a patient is having normal or impaired nocturnal erections will help to distinguish between organic vs. psychogenic causes of ED.
History and Examination
In cases of suspected ED, a thorough history and examination is necessary in order to ascertain the underlying cause of dysfunction.11,12 This will serve to inform management strategies for the patient. Clinical assessment of ED is frequently carried out by primary care providers, with referral to urology warranted for refractory, complex or uncertain cases. Chiefly, both history and examination should be undertaken in a private, safe environment, where patients are able to feel comfortable discussing their sexual history.
Introduce yourself, your role
Confirm the patient’s name and date of birth
Obtain consent for history-taking
Patient’s with suspected ED will primarily complain of difficulties initiating or sustaining an erection. Features of this symptom should be fully explored using the prompts below.
History of Presenting Complaint
Onset of sexual dysfunction (i.e. short, gradual)
Duration of sexual dysfunction (i.e. lifetime or acquired)
Difficulties with arousal
Rigidity of erections
Duration of sexual stimulation
Difficulties with ejaculation
Difficulties with orgasm
Presence/absence of morning erections
The International Index of Erectile Function (IIEF-5) is an objective 5-item questionnaire frequently used by urologists to assess the severity of a patient’s ED. The tool asks patients to consider the following six questions on a scale of one to five (Table 2).
Table 2. The International Index of Erectile Function (IIEF-5) Scoring System for ED13
Over the past 6 months…
How do you rate your confidence that you could get and keep an erection?
1- Very low
5- Very high
When you had erections with sexual stimulation, how often were your erections hard enough for penetration?
1- Almost never/never
2- A few times
4- Most times
5- Almost always/always
During sexual intercourse, how often were you able to maintain your erection after you had penetrated your partner?
1- Almost never/never
2- A few times
4- Most times
5- Almost always/always
During sexual intercourse, how difficult was it to maintain your erection to completion of intercourse?
1- Extremely difficult
2- Very difficult
4- Slightly difficult
5- Not difficult
When you attempted sexual intercourse, how often was it satisfactory for you?
1- Almost never/never
2- A few times
4- Most times
5- Almost always/always
Past Medical History
Previous consults for sexual dysfunction, previous trials of treatment
Other medical co-morbidities
Previous operations including pelvic operations
It is important to screen for psychiatric co-morbidities such as depression and anxiety
Medications and Allergies
It is important to ask about antipsychotics, antidepressants and antihypertensives as these medications are known to cause ED.
History of smoking
Illicit drug use
Diet and exercise
Occupation- important if related to the suspected underlying cause of the patient’s ED (i.e. injury at work)
Sexual partners/current relationship status and partner’s reaction to sexual problems
*It is crucial to explore the patient’s relationships with their sexual partners. If the cause of ED is thought to be psychogenic, the nature of these relationships will allow you to better understand the origins of the dysfunction. Relationship stress has been implicated with sexual dysfunction in men.14
At the end of history-taking, it is important to prompt patients about their personal feelings surrounding the cause of their sexual dysfunction, concerns about diagnosis, and expectations for treatment. This serves to better understand the patient’s baseline understanding of ED as a condition, and its’ associated investigation and management strategies. However, beyond this, this moment of pause allows patients to disclose any further information that may have been missed in the preceding discussions.
Following a thorough history, a male genital examination should be performed to rule-out obvious structural or neurological causes of ED. Due to the sensitive nature of the examination, a chaperone should always be offered regardless of provider gender.
In addition, a thorough cardiovascular, neurological (upper and lower limb) and endocrine assessment should be performed on patients with suspected ED. This is to investigate for possible underlying causes of the dysfunction (Table 1).
Investigations should be selected based on the clinical judgement of the cause of ED. For instance, patients with vascular risk factors should undergo those tests which evaluate cardiovascular risk status. Below is a sample of routine investigations to be carried out:
Fasting glucose and/or HbA1C
Serum total testosterone (best taken in the early morning) – if ↓ testosterone, measure serum prolactin for further investigation of secondary hypogonadism
In cases of complex or refractory ED, urologists may choose to perform an additional set of specialised tests and imaging:
Nocturnal penile tumescence testing (NPT) – Used to distinguish between organic vs. psychogenic ED. The patient wears the NPT device overnight, measuring number, tumescence and rigidity of erections.
Duplex doppler imaging/angiography – If a vascular cause of ED suspected
Management of ED
Increasingly, primary care physicians are managing ED with medical therapies alone.6 However, depending on the cause of ED, surgery may be warranted in certain cases. Both medical and surgical therapies for ED are discussed further below. Governed by the NICE guidelines, the approach to management can be stratified as strategies employed in both primary care and secondary care.16
1. Advice to modify risk factors
Where applicable, patients should be encouraged to adopt healthy lifestyle behaviours, including not smoking, minimal alcohol intake, weight loss and diet. Many of these risk factors are linked to CV disease and diabetes, among others, which are known to predispose to ED. Research shows that in many cases, addressing the lifestyle risk factors that predispose to ED, among other diseases, can significantly mitigate or eliminate the disease.17
If a medication is suspected to be the cause of the ED, consider substitution or withdrawal of this substance for 2 weeks and review the effect.
2. Pharmacological therapies
Phosphodiesterase-5 inhibitors (PDE-5 inhibitors). These drugs arrest PDE-5, allowing for the prolongation of cGMP and subsequent relaxation of penile blood vessels (sildenafil, vardenafil, avanafil).
Consult BNF for appropriate drug dosages (usually 25-100mg). Try drug at full dose prior to switching therapy. Frequency of use may vary with the severity of the patient’s ED.
It is essential to counsel patients on the appropriate practice of PDE-5 inhibitors – take on an empty stomach 30 minutes prior to intercourse, avoid alcohol and fatty meals as it reduces drug absorption.
The drug is intended to last for roughly 4 hours (if an erection lasts longer than 4 hours, the patient should seek urgent care for risk of priapism)
PDE-5 contraindications include concurrent nitrate use. Caution is required when treating patients with cardiovascular or cerebrovascular disease in the previous 6 months (hypo/hypertension).
PDE-5 side effects include headache, flushing, dizziness, dyspepsia and rhinitis
Arrange follow-up at 6-8 weeks for review of treatment
Alprostadil also comes in a topical cream and intraurethral application (MUSE) formulation which can be applied regularly by the patient at home prior to sexual intercourse.
3. Penile prosthesis
Recommended as a surgical treatment for patients who have failed previous trials of management. Prosthetic options are inflatable implants vs. semirigid rods. In inflatable implants, the patient presses a pump which fills a surgically-implanted cylinder with fluid, thereby propelling an erection. Contrastingly, with semirigid rods, the penis remains rigid at all times and patients may choose to manoeuvre the device upwards to conceal their erection in times outwith sexual activity. Penile implants last for 10-15 years. The risks of prothesis are infection, implant malfunction and internal erosion/adhesion.
Hormone treatments – patients may be referred to an endocrinologist for hormone replacement if a deficiency in reproductive hormones is found on laboratory testing
Psychosexual counselling – patients may be referred for specialist counselling services if the cause of ED is considered to have a psychogenic component (either stand-alone or mixed) and if purely organic causes of ED have been ruled out
*After the use of any of the above therapies, if a man presents with priapism, defined as an erection lasting greater than 4 hours, urgent hospitalisation is required for further investigation and management.
Prognosis of ED
If an underlying organic cause of ED is identified and reversible, the probability of curing ED is greatly increased. However, if refractory to various treatment modalities, patients with ED are at increased risk for psychiatric co-morbidities such as anxiety and depression. This may further generate relationship and interpersonal struggles, significantly affecting a patient’s quality of life. Moreover, ED is known to be a risk factor in itself for CV disease, therefore if left untreated, could predispose the patient to greater risks of stroke and coronary artery disease.3
What is it? – Difficulty initiating or maintaining an erection
Causes – Organic vs. Psychogenic
Laboratory tests (FBC, U&E, LFTs, HbA1c)
Primary care management:
Secondary care management:
Alprostadil injections and creams
ED is a risk factor for anxiety, depression and cardiovascular disease
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