Priapism

Definition

Prolonged penile erection (>4 hours), continues without sexual stimulation and despite ejaculation/orgasm.

Classification

Ischaemic (low flow) – more common. Painful due to ischaemia, with pain increasing with the duration of the priapism. Caused by venous outflow obstruction/thrombosis. Presents as rigid erection sparing the glans. If persists >12 hours, priapism can lead to permanent fibrosis and calcification. Causes: idiopathic, haematological (eg sickle cell disease) and medication (vasoactive erectile agents, antipsychotics, anticoagulants, antidepressants, anti-hypertensives, hormone therapy).

Non-ischaemic (high flow) – less common. Painless or only uncomfortable with no risk of necrosis. Normally secondary to trauma, unregulated inflow due to rupture of cavernosal artery.

Rarer subtypes:

• Recurrent/stuttering – more common in sickle cell disease patients. Frequent prolonged and painful erections. Treatment involves oxygenation, hydration, analgesia and possible exchange transfusion.
• Priapism in spinal shock – occurs in spinal injury with loss of sympathetic tone leading to high-flow, non-ischaemic priapism. Requires no treatment.

If in doubt, manage as ischaemic priapism

Clinical History

If possible, establish and document

• Duration of erection (<48 hours, 48-72 hours, >72 hours)
• Any underlying haematological disorder
• Current medication
• Illicit drug use
• Symptoms to suggest pelvic malignancy
• Previous episodes
• Recent perineal/penile trauma
• Neurological symptoms

Examination

• Penis – look for evidence of sparing of the glans and trauma
• Abdomen and DRE – look for evidence of underlying pelvic malignancy
• Neurological – evidence of spinal cord injury

Investigations (if available)

• Bloods – FBC, electrolytes, clotting, blood smear/sickle cell screen
• Urine and blood toxicology if recreational drug use
• Penile bloods gas from first aspirate to help differentiate ischaemic (pH <7.25, pCO₂ >8 kPa, pO₂ <4 kPa) and non-ischaemic priapism but normoxia does not exclude ischemic priapism.
• Imaging
  • US penile doppler
  • Abdominal and pelvic CT/MRI – penile MRI can be used to assess viability of corpus cavernosum in refractory cases

Management

Ischaemic – for patients with prolonged priapism or priapism that proves refractory to the above interventions, Urology specialist input is required for surgical shunt formation and consideration of early penile prosthesis insertion

Non-ischaemic – manage conservatively. If does not spontaneously resolve, will need specialist intervention in a unit that can offer super selective arteriography and embolization.

Follow up

All patients will need specialist follow-up to monitor for late-onset erectile dysfunction

Insert a large 19-gauge needle or butterfly needle into lateral aspect of one corpus cavernosum, at the 2 or 10 o’clock position 

Aspirate and wash-out to achieve detumescence – remove 10-15 mL of static blood and replace with saline until aspirate is bright red or detumescence is achieved. Expect to aspirate 200-300 mL.  

If fails or returns, repeat once. 

If fails or returns again, evacuate patient without delay for further management.

Preparation: Position patient supine, clean area of gross contamination/debris, apply skin prep (chlorhexidine or povidone-iodine solution) to suprapubic region, penis, and scrotum. Apply sterile drape to area.

Inject small volume of local anaesthetic to skin in the midline at the dorsum of base of penis with small gauge needle to raise bleb of local anaesthetic (LA, typically lidocaine 1%, without adrenaline).

Insert a larger gauge needle, perpendicular to the skin, via the anaesthetic bleb, and advance it until it touches the pubic symphysis. Withdraw the needle slightly and adjust to pass it below the pubic symphysis, aiming it slightly laterally by around 20^o, and advance approximately a further 3 to 5 mm.

Attempt to aspirate to ensure the needle is not in a blood vessel. Inject LA (c. 10 mL), there should be very little or no resistance.

Repeat on the contralateral side taking care to withdraw the needle to the bleb before advancing again to prevent inadvertent damage to midline structures (suspensory ligament and blood vessels).

Figure 1: Needle is inserted in midline and advanced 3- 5mm to pass below pubic symphysis on each side.

Figure 2: Cross section of penile anatomy. Needle inserted at midline and LA applied at depth of 3-5 mm bilaterally. 

Figure 3: Sagittal section of penile anatomy. Needle inserted at midline, angled 20^o laterally and advanced 3-5 mm to pass below pubic symphysis