Erectile Dysfunction

Differential Diagnosis

Common Diagnoses

  • Excessive Alcohol Intake
  • Relationship Dysfunction
  • Vascular: Arterial Insufficiency (Arteriopathy) or Excessive Venous Drainage
  • Iatrogenic (e.g. Prostatic Cancer Treatments, Hypotensives, some Antidepressants)
  • Anxiety
  • Depression

Occasional Diagnoses

  • Testosterone Deficiency (May be Primary or Secondary)
  • Diabetic Autonomic Neuropathy
  • Trauma: Pelvic or Spinal Fracture, Trauma to Penis, Post-TURP
  • Anatomical: Phimosis, Tight Frenulum
  • Excessive Cigarette Smoking
  • Peyronie’s Disease
  • Drug Abuse (e.g. Heroin, Amphetamines)

Rare Diagnoses

  • Fetishism (Erection only Possible with Unusual Stimuli)
  • Spinal Cord Compression: Tumour
  • Thrombosis of a Corpus Cavernosum
  • Neurological: Tabes Dorsalis, Multiple Sclerosis

Ready Reckoner

Key distinguishing features of the most common diagnoses

Depression/ AnxietyAlcoholRelationship DysfunctionVascularDrugs
TATT/sleep ProblemYesPossiblePossibleNoNo
Occasional OnlyPossibleNoYesNoNo
Full Morning ErectionYesNoYesNoNo
Reduced Foot PulsesNoNoNoYesNo
Taking MedicationPossibleNoNoNoYes

Possible Investigations


Possible:Blood sugar or HbA1c, FBC, LFT, endocrine assays (testosterone, prolactin, FSH/ LH, TSH), cholesterol, PSA.

Small Print:Doppler flow studies, angiography, intracorporeal prostaglandin injection test, MRI scanning – all likely to be specialist initiated.

  • Urinalysis: An essential easy screen for undiagnosed diabetes.
  • Blood sugar or HbA1c: To confirm diabetes.
  • FBC and LFT possibly helpful in alcohol excess (raised MCV and possible LFT abnormalities).
  • Testosterone levels reduced in primary or secondary hypogonadism. Prolactin, FSH/LH and TSH check pituitary function. Erectile dysfunction may be a sign of cardiovascular disease – so in certain patients a cholesterol level would be warranted.
  • The link between prostate cancer and erectile dysfunction is far from clear. Some guidelines recommend PSA in this situation to assess for possible prostate cancer; judge each case on its merits and according to other symptoms and the man’s wishes.
  • Doppler flow studies of superficial and deep penile arterial flow assess arterial sufficiency. Angiography may be necessary if symptoms suggest significant lower limb arterial insufficiency associated with impotence.
  • Intracorporeal prostaglandin injection test: Immediate and prolonged response indicates neurological problems. Good initial response with rapid failure indicates excessive venous drainage.
  • Possible neurological causes will occasionally require further investigation (e.g. MRI scanning for cord lesions or MS).

Top Tips

  • Establish whether the patient can get an erection at any time (e.g. early morning). If he can, then the cause is unlikely to be organic. Take a positive approach – many psychological causes are transient.
  • Don’t be too quick to diagnose anxiety as the underlying problem. This may be the effect, rather than the cause, of the impotence.
  • Erectile dysfunction is often presented as a ‘by the way’ or ‘while I’m here’ symptom. The temptation is to invite the patient to book a further appointment, but bear in mind that this may represent a lost opportunity to help, as he may not return.
  • Demonstrate that you are taking the problem seriously – for example, by performing an appropriate examination or by inviting the patient’s partner to attend a subsequent appointment.

Red Flags

  • Sudden onset of erectile dysfunction with saddle anaesthesia and sphincter disturbance indicates a cauda equina lesion. Refer urgently.
  • An erection which is consistently lost after a predictable period is likely to be organic – probably vascular – in origin.
  • Do not forget that alcohol and drug abuse are possible causes. Look in the notes for clues and make specific enquiry, as these problems are unlikely to be volunteered.
  • Erectile dysfunction may well be a marker for vascular disease elsewhere. Extend your assessment as appropriate.

Published: 2nd August 2022 Updated: 10th April 2024

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