Priapism is a persistent penile erection that persists beyond hours of sexual stimulation or causes an uncontrolled erection lasting at least 4 hours, unrelated to sexual stimulation.
There are haematological dyscrasias vascular and other disorders, infections (toxin mediated), metabolic disorders, neurogenic disorders, neoplasms (metastatic or regional infiltration) and medications in the etiology. Although the list is very long, we can list them under these main headings.
Sickle cell anemia is the most common cause of hematological disorders. The scorpion sting, spider bite and malaria can be listed in the etiology under the heading of infections and toxin. Another common cause is drugs. Other causative drugs are vasoactive erectile agents (i.e., papaverine, phentolamine, prostaglandin E1/alprostadil,combination of intracavernous therapies), α-adrenergic receptor antagonists (i.e., prazosin, terazosin, doxazosin and tamsulosin), anti-anxiety agents (hydroxyzine), anticoagulants (heparin and warfarin) Antidepressants and antipsychotics (i.e., trazodone, bupropion, fluoxetine, sertraline, lithium, clozapine, risperidone, olanzapine, chlorpromazine, thiorizadine, phenothiazines and methylphenidate.
Forms of ischemic priapism
There are three forms of priapism: ischemic, non-ischemic, and recurrent.
In ischemic priapism, the corpora (a pair of cylindrical structures in the penis when the penis is erect) is completely hard and tender, but the glans penis (head of the penis) is soft. The patient complains of severe pain. Pelvic examination may reveal an underlying pelvic or genitourinary malignancy. Depending on the long and involuntary confinement of blood in the penis, there is a dominance of carbon dioxide in the blood gas in the penis.
The non-ischemic type has a history of trauma. There is no dominance of carbon dioxide in the blood and pain is rare.
Recurrent priapism is usually self-limited and lasts less than three to four hours per attack. However, there is a potential for conversion to complete ischemic priapism in one-third of cases requiring immediate intervention.
Medical and sexual history, laboratory tests and imaging are the criteria for diagnosis.
In the patient presenting with priapism, blood gas and hematological abnormalities should be examined in laboratory tests. Normal arterial blood (room air) (similar values are found in arterial priapism) is oxygen level > 90 mmHg, carbon dioxide level < 40 mmHg, and blood pH 7.40. Normal mixed venous blood (room air) oxygen level is 40 mmHg, carbon dioxide level 50 mmHg, and blood pH 7.35. Ischaemic priapism (first corporal aspirate) is oxygen level <30 mmHg, carbon dioxide level >60 mmHg, and blood pH < 7.25.
Color Doppler USG of the penis and perineum can distinguish between ischemic and non-ischemic priapism in addition to advice and alternative or blood gas analysis after clinical diagnosis.
Penile MRI can be used in the diagnostic treatment of priapism and can help to detect corpora cavernosa viability and penile fibrosis visit in selected cases of ischemic priapism. In particular, durable priapism or delayed (>48 h) dimensions can be evaluated as smooth muscle viability.
Initial conservativ measures
Local anaesthesia of the penis
Insert wide bore buferfly (16-18 G) through the glans into the corpora cavernosa
Aspirate cavernosal blood until bright red arterial blood is obtained.
Irrigate with 0.90% w/v saline solution
Inject intracavernosal adrenoceptor agonist
Current first-line therapy is phenylephrine with aliquots of 200 µg being injected every 3-5 minutes until detumescence is achieved (maximum dose of phenylephrine is 1mg within 1 hour)
Consider primary penile implantation if priapism has been present for more than 48 hours