priapism

Introduction

priapism is the unwanted, very prolonged (more than 4hrs without sexual stimulation) erection of the penis which may constitute a rare urologic emergency as risk of permanent scarring of the penis increases after 4hrs of ischaemic priapism and occurs in all patients after 48hrs of ischaemic priapism, this may result in disfigurement, erectile dysfunction or in severe cases, penile gangrene
rarely, clitoral priapism may occur in women
named after the Greek fertility god Priapus who is often represented with a disproportionately large, permanent erection
there are 3 main types:
- ischaemic priapism (low blood flow)
  - accounts for over 90% of cases of priapism
  - painful, most of penis is hard except for the glans
  - most commonly caused by sickle cell disease (SCD)
  - Mx is usually with anaesthetic penile nerve block and aspiration of blood from the corpus cavernosum
- non-ischaemic priapism (high blood flow)
  - whole of penis is only moderately hard
  - this is usually due to acute spinal cord injury or blunt trauma to the penis causing laceration of the cavernous artery and resultant arterial-lacunar fistula
  - Mx is usually with cold packs and compression
- recurrent ischaemic intermittent priapism

priapism is a time critical emergency - persistence approaching 12 hours or more is increasingly associated with permanent erectile dysfunction

sickle cell disease (SCD)
- affects over 40% of men with sickle cell at some stage
- initial Rx is usually with intravenous fluids, pain medication, and oxygen therapy, but if ressolution does not occur then aspiration is indicated
medications
- drugs used to Rx erectile dysfunction:
  - sildenafil (Viagra)
- anti-psychotic medications such as chlorpromazine (Largactil)
- SSRI/SNRI antidepressants such as fluoxetine
- prostaglandin E1
- non-steroidal anti-inflammatory drugs (NSAIDs)
- warfarin
- alpha adrenergic blockers
- cocaine
- marijuana / cannabis / THC
- melanocortin receptor MC₄ agonists in high dose eg. melanotan II
myelofibrosis, myeloproliferative disorders, multiple myeloma, thalassaemia, leukaemia
malaria
dermatomyositis
red back spider bites / Latrodectism
Brazilian Wandering spider bites
scorpion stings
gout
acute spinal cord injury
penile or perineal trauma

consent for procedure
cardiac monitor as likely to require use of sympathomimetics
if available, nitrous oxide or other adjunct is helpful to assist with local anaesthetic administration
appropriate PPE including sterile gloves, gown and face shield
sterile dressing tray with gauzes
1% lignocaine local anaesthetic
25G needle and 5mL syringe
21G butterfly
multiple 10mL and 20mL syringes to aspirate blood and flush with 0.9% saline
0.9% saline ampoules
alpha agonist agent to inject into corpus cavernosum such as:
- phenylephrine
- metaraminol
will probably need two assistants

inject 1-2% lignocaine LA under fascia at base of dorsum of penis at 10 o'clock and at 2 o'clock

insert 21G butterfly into corpus cavernosum until blood is aspirated
aspirate blood - send a sample for blood gas analysis
if blood is clotted, may need larger bore needle and large volumes of 0.9% saline to irrigate corpus cavernosum
if no resolution after 100mL or so of blood is aspirated, then resort to alpha blocker
- eg. titrations of 100mcg in 1mL phenylephrine injected into corpus cavernosum and await response over next 2-5 minutes and re-try