Background Information

Definition

ED is defined as the persistent inability to attain and maintain an erection sufficient to permit satisfactory sexual performance.

Note that erectile dysfunction is a symptom, not a disease.

Aetiology

Aetiology of ED is traditionally classified into:

• Organic, and
• Psychogenic

However, most cases of ED are actually of mixed aetiology.

Organic Causes

Vasculogenic – most common	Cardiovascular disease Diabetes mellitus Smoking Metabolic syndrome, hyperlipidaemia, obesity Lack of regular physical exercise
Neurogenic	Peripheral causes Diabetes mellitus (autonomic neuropathy) Chronic renal failure / chronic liver failure Prostate cancer interventions (radical prostatectomy and radical radiotherapy) Other pelvic surgery e.g. radical cystectomy, colorectal surgery Surgery of the urethra (urethral stricture, open urethroplasty, etc.) Central causes Degenerative disorders (e.g. MS, PD, multiple atrophy) Stroke Spinal cord trauma / disease CNS tumours
Hormonal	Hypogonadism Hyperthyroidism Hypercortisolism (Cushing’s syndrome) and hypocortisolism (adrenal insufficiency)
Anatomical	Peyronie’s disease Phimosis Hypospadias Micropenis Penile cancer (and other tumours of the external genitalia)
Trauma	Penile fracture Pelvic fracture
Drug-induced	Antihypertensives (beta blockers and thiazide diuretics) Antidepressants (esp. SSRIs) Antipsychotics Antiandrogens (5 alpha reductase inhibitors, GnRH agonist and antagonists) Recreational drugs (e.g. heroin, cocaine, marijuana, methadone, synthetic drugs, anabolic steroids, excessive alcohol intake)

Psychogenic Causes

Generalised	Lack of arousability Disorders of sexual intimacy
Situational	Partner-related Relationship issues Performance anxiety

Diagnosis

ED itself is a clinical diagnosis, investigations are performed to identify underlying causes of ED

History Taking

ED-focused history taking that differentiates between organic and psychogenic causes:

History Domain	Key questions to ask	Suggests organic ED	Suggests psychogenic ED
Onset	“When did the problem start?”	Gradual, progressive onset	Sudden onset
Course	“Has it been getting worse over time?”	Progressive deterioration	Fluctuating, intermittent
Situational vs Global	“Does it happen in all situations or only with a partner?”	Present in all settings (all partners and masturbation)	Situation-specific (e.g. only with a specific partner, or only with partner but normal with masturbation)
Morning Erections	“Do you still get morning erections?”	Absent or reduced	Preserved
Libido (sexual desire)	“Has your sex drive changed?”	Reduced libido	Normal libido
Erection Quality	“Is it difficult to get an erection or to maintain one?”	Both initiation and maintenance affected	Usually maintenance issue
Ejaculation / Orgasm	“Any issues with ejaculation or orgasm?”	May be abnormal	Usually normal
Psychological stressors	“Any recent stress, anxiety or relationship issues?”	May coexist but not primary	Strong association
Performance anxiety	“Does worrying about performance make it worse?”	Minimal effect	Key feature

Cardiovascular Risk Assessment

Patients who seek treatment for sexual dysfunction have a high prevalence of cardiovascular disease:

• ED significantly increases the risk of cardiovascular disease, coronary heart disease, stroke, atrial fibrillation, cardiovascular and all-cause mortality
• ED should be considered a precursor of CVD

Therefore, it is important to perform cardiovascular risk assessment in ED patients with no overt disease or cardiac symptoms

 

Assess the cardiac risk of sexual activity. High risk is defined as ANY of the following:

• Unstable or refractory angina
• Recent MI (within the last 2 weeks)
• Reduced ejection fraction heart failure (NYHA class IV)
• Uncontrolled hypertension
• High-risk arrhythmia (exercise-induced ventricular tachycardia, implanted internal cardioverter defibrillator with frequent shocks, and poorly controlled atrial fibrillation)
• Hypertrophic obstructive or other cardiomyopathy
• Moderate-to-severe VHD

Physical Examination

All patients should be given a physical examination focused on:

• Genitourinary system – check for penile structural abnormalities, testicular abnormalities
• Endocrine system – check for signs of hypogonadism (e.g. testicular atrophy, alterations in secondary sexual characteristics, sparse body hair, gynaecomastia, reduced muscle mass)
• Cardiovascular system
• Neurological system – check for neuropathy

 

The following should be measured / assessed:

• Heart rate
• Blood pressure
• BMI or waist circumference

Laboratory Testing

Testing for ALL patients:

• Fasting blood glucose or HbA1c
• Lipid profile
• Fasting serum total testosterone (9-11 am)

Additional investigations to consider, depending on the underlying cause and clinical judgement:

FBC	Anaemia can contribute to reduced libido
U&E	CKD is associated with ED
LFTs	Chronic liver disease is associated with ED
TFTs	Both hyper- or hypothyroidism can cause ED
PSA	If prostate cancer is suspected

Advanced Work-Up Tests

The following are NOT routinely necessary, and are only performed in secondary care:

• Psychopathological and psychosocial assessment – for psychogenic ED
• Nocturnal penile tumescence and rigidity test – objectively differentiate between organic and psychogenic ED (patients with psychogenic ED usually have normal findings in the NPTR test)
• Intracavernous injection test
• Dynamic duplex ultrasound of the penis – usually used if vasculogenic aetiology is suspected
• Arteriography and dynamic infusion cavernosometry or cavernosography – only in patients who are being considered for penile revascularisation

Management

Referral Criteria

Speciality of referral	Indication
Urology	ANY of the following: Patient is young Lifelong history of ED (due to possible primary ED) History of pelvic / perineal / genital trauma Presence of penile structural abnormality or abnormal testicular examination
Cardiology	ANY of the following: High cardiac risk of sexual activity – stop ALL sexual activity until specialist assessment PDE-5 inhibitors are contraindicated
Endocrinology	ANY of the following: Low serum testosterone Abnormalities in LH / FSH / prolactin levels Testosterone replacement is being considered

Primary Care Management

Conservative / General Management

Before offering any therapeutic options:

• Identify and treat curable causes of ED
• Advice on lifestyle changes and risk factor modifications
• Provide education and counselling to the patient +/- their partner

Pharmacological Management

1st line: PDE-5 inhibitor (sildenafil / tadalafil / vardenafil / avanafil)

• MoA: PDE normally breaks down cGMP → prolonge cGMP-mediated smooth muscle relaxation in the corpora cavernosa
• Typically taken intermittently (15-60 min before sexual activity), as needed
• Tadalafil (long acting: up to 36 hours) may be prescribed once daily in specific circumstances

Arrange follow-up 6–8 weeks after starting treatment

• If initial treatment is ineffective:
  • Reassess for underlying causes and risk factors, and manage appropriately
  • Note that hypogonadism and a low testosterone level may result in a reduced response or non-response to PDE-5 inhibitors
• Ensure it is taken correctly and advise on possible dose and drug regimen changes
• Suggest a trial of at least two different PDE-5 inhibitors taken sequentially before being classed as a ‘non-responder’

Patients who fail to respond to the maximum dose of at least two different PDE-5 inhibitors should be referred to a specialist

Secondary Care Management

Options include:

• Alprostadil penile intracavernous injections
• Vacuum erection assistance devices
• Medicated urethral system for erection
• Vascular surgery/angioplasty
• Penile prostheses

References