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Priapism

Created: 20/9/2005
Updated: 19/8/2007

 

Priapism

Definition

Prolonged penile erection not accompanied by sexual desire

(except in high-flow type priapism is often accompanied by pain)

Typically affects only the corpora cavernosa (corpus spongiosum involved in very rare cases)

Classification

Traditionally classified as primary/idiopathic or secondary

More recently priapism has been classified haemodynamically:

  • Low-flow (ischaemic/anoxic)
  • High-flow (non-ischaemic/arteriogenic)
  • Recurrent/stuttering

Epidemiology

  • Can occur in all age-groups
  • Peak incidence between 5-10 and 20-50 years
    • In younger group most case are associated with sickle-cell or neoplasm
    • In older group many case are idiopathic

Aetiology

1) Idiopathic/secondary

2) Secondary

  • Iatrogenic (intracavernous injection)
  • Drugs
    • Alpha-blockers
    • Antidepressants
    • Anticoagulants (heparin)
    • Recreational drugs
    • TPN
  • Thrombo-embolic (sickle-cell, thallasaemia, leukaemia, fat emboli)
  • Neurological (spinal cord lesions, cauda equine, anaesthesia, autonomic neuropathy/diabetes)
  • Neoplastic (malignant infiltration from eg. bladder)
  • Trauma (perineal/genital causing damage to cavernosal artery or AV fistula – usually high-flow)
  • Infectious/toxic (malaria, rabies)

Pathophysiology

Low-flow priapism is a failure of the detumescence mechanism (smooth muscle contraction, decrease in arterial inflow, and increase in venous outflow)

  • Results in increasing intracavernous pressure and worsening ischaemia
  • 4-8 hours erection becomes painful and there is irreversible smooth muscle contractile dysfunction
  • 12 hours - interstitial oedema and damage to the sinusoidal endothelium
  • 48 hours sinusoidal thrombi, smooth muscle cells become fibrotic or frankly necrotic
  • Untreated over 2-4 weeks – necrotic corporeal smooth muscle is replaced by fibrous tissue

High-flow priapism

  • All priapism begins as high-flow (most-proceed to a veno-occlusive disorder)
  • High arterial flow continues in some cases, with adequate venous outflow and well-oxygenated corpora cavernosum
  • Most commonly occurs after blunt perineal/genital trauma causing damage to cavernosal artery or AV fistula , and occurs in young men

Recurrent/stuttering priapism often occurs in patients with sickle-cell and in those who have had previous episodes of priapism - mechanism is unknown

Clinical features

Low-flow

Occurs during sleep
Pain is mild initially then becomes severe
Penis is rigid
Cavernous blood - black (ischaemic), PO2 <30mmHg, PCO2 >80mmHg, pH <7.25
Colour Doppler shows no flow
Vessels intact on arteriography

High-flow

Occurs following trauma
Pain is mild to moderate
Penis is turgid (because venous channels are still open)
Cavernous blood – red (non-ischaemic), PO2 >50mmHg, PCO2 >50mmHg, pH >7.5
Colour Doppler shows flow or fistula
Arteriography may show A-V malformation

Management (refer to local protocols)

  • History and examination
  • Analgesia
  • Urinalysis and culture (exclude UTI)
  • Haematology (where appropriate exclude Sickle-cell or leukaemia)
  • Treat underlying cause if present eg rehydration, oxygenation and possibly exhange transfusion in sickle cell patients
  • Cavernous blood gas measurement (followed by colour Doppler if doubt exists)

Low-flow

  • Aspiration of blood from the corpora
  • Repeat if fails
  • Corporal injection of 250µg phenylephrine with full cardiovascular monitoring
  • NB phenylephrine is a selective alpha 1 adrenoreceptor agonist, safer than other agents eg metaraminol which are unselective and have a more pronounced effect on BP. Phenylephrine solution made by mixing 1ml of 1% (10mg/ml) phenylephrine with 19 mls normal saline - 250µg is 0.5mls, 500µg is 1ml
  • If fails after 5 minutes repeat 250µg phenylephrine injection
  • If fails after 5 minutes repeat with 500µg phenylephrine injection
  • If fails surgical treatment
  • All aim to shunt cavernosal blood to low-pressure vascular system
    • The Winter technique
      • Following penile block, trucut needle inserted through glans into corpora cavernosa. Puncture repeated four times and corpora squeezed to evacuate hypoxic blood
      • Preserves potency in a significant proportion of patients
    • Corporo-spongiosal shunt – usually successful but approx 50% patients remain impotent post-op
    • Corporo-saphenous shunt – LSV mobilsed, divided in mid-thigh, tunnelled subcutaneously and anastomosed to tunica albuginea on ipsilateral corpus

Recurrent/stuttering priapism

Such patients represent a considerable management problem

Treatment is aimed at:

  • Preventing prolonged erections eg with hormonal manipulation such as LHRH anlogues/antiandrogens or possibly digoxin
  • Treating them when they arise eg terbutaline

High-flow

  • First objective is to make the diagnosis
  • Interventions involve selective arterial embolisation of central penile artery
  • Surgical interventions involve ligation of ipsilateral internal pudendal artery, common penile artery or microvascular ligation of the fistula between the artery and sinusoidal spaces
  • Methylene blue may be of use through its inhibition of guanylate cyclase and resultant decrease in nitric oxide levels, but effects may be short-lived
  • NB It may be appropriate just to observe patient as potency can be preserved for many years and is painless

Prognosis

Untreated low-flow priapism leads to fibrosis and impotence. However, almost all patients will recover their previous potency if priapism aborted within 12-24 hours with medical therapy

References
Winter, CC. Priapism cured by creation of a fistula between the glans penis and the corpora cavernosa. J Urol 1978;119:227-228


ArticleDate:20050920
SiteSection: Article
 
   
    
                                            



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