Prolonged unwanted erection (> 4 hours), often painful and not associated with sexual arousal

Aetiology

• Intracorporeal injection for ED e.g. papavarine
• Trauma (penile/perineal)
• Haematological dyscrasias e.g. sickle cell
• Neurological conditions
• Idiopathic

Pathophysiology

• Ischaemic (veno-occlusive or low-flow)
  • Vascular stasis in penis and decreased venous outlfow - a true compartment syndrome
  • Corposa cavernosa are rigit and tender, penis often painful
• Non-ischaemic (less urgent)
  • Traumatic distuption of penile vasculature results in unregulated blood entry and filling of corpora
  • Fistula formation betweenc cavernous artrery and lacinar spaces allows blood to bypass the normal helicine arteriolar bed

Investigations

• Aspirate blood from corpus cavernosum
  • Dark blood, low O2 and high CO2 in low-flow
  • Normal arterial blood in high-flow
• Colour duplex USS:
  • Minimal or absent flow in cavernosal arteries in low-flow
  • Normal to high flow in non-ischaemic priapism

Management

Ischaemic

• Aspiration +/- irrigation with saline
• If fails to resolve - injection of ⍺-agonist e.g. phenylephrine
• If fails to resolve - surgical shunt
• Ischaemic priapism > 48-72 hours unlikely to respond to intracavernosal treatment
• For very delayed presentation, may even consider immediate placement of a penile prosthesis