Priapism

Because ischemic priapism causes the blood to remain in the penis for unusually long periods of time, the blood becomes deprived of oxygen, which can cause damage to the penile tissue. Such damage can result in erectile dysfunction or disfigurement of the penis.[9] In extreme cases, if the penis develops severe vascular disease, the priapism can result in penile gangrene.[10]

Causes of low-flow priapism include sickle cell anemia (most common in children), leukemia, and other blood dyscrasias such as thalassemia and multiple myeloma, and the use of various drugs, as well as cancers.[11] A genome-wide association study on Brazilian patients with sickle cell disease identified four single nucleotide polymorphisms in LINC02537 and NAALADL2 significantly associated with priapism.[12]

Other conditions such as Fabry's disease, as well as neurologic disorders such as spinal cord lesions and spinal cord trauma (priapism has been reported in people who have been hanged; see death erection).

Priapism can also be caused by reactions to medications. The most common medications that cause priapism are intra-cavernous injections for the treatment of erectile dysfunction (papaverine, alprostadil). Other medication groups reported are antihypertensives, antipsychotics (e.g., chlorpromazine, clozapine), antidepressants (most notably trazodone), anti-convulsant and mood stabilizer drugs such as sodium valproate.[13] Anticoagulants, cantharides (Spanish Fly) and recreational drugs (alcohol, heroin and cocaine) have been associated. Priapism is also known to occur from bites of the Brazilian wandering spider.[14]

Causes of high-flow priapism include:

• blunt trauma to the perineum or penis, with laceration of the cavernous artery, which can generate an arterial-lacunar fistula.[11]
• Anticoagulants (heparin and warfarin).
• Antihypertensives (i.e., hydralazine, guanethidine and propranolol).
• Hormones (i.e., gonadotropin releasing hormone and testosterone).

Color Doppler ultrasound demonstrating a hypoechoic collection that corresponds to hematoma with arteriovenous fistula secondary to traumatic injury of the penis due to impact with bicycle handlebars, resulting in high-flow priapism.[11]

Penile ultrasonography with Doppler is the imaging method of choice, because it is noninvasive, widely available, and highly sensitive. By means of this method, it is possible to diagnose priapism and differentiate between its low- and high-flow forms.[11]

In low-flow (ischemic) priapism the flow in the cavernous arteries is reduced or absent. As the condition progresses, there is an increase in echogenicity of the corpora cavernosa, attributed to tissue edema. Eventually, changes in the echotexture of the corpora cavernosa can be observed due to the fibrotic transformation generated by tissue anoxia.[11]

In high-flow priapism normal or increased, turbulent blood flow in the cavernous arteries is seen. The area surrounding the fistula presents a hypoechoic, irregular lesion in the cavernous tissue.[11]

Orally administered pseudoephedrine is a first-line treatment for priapism.[15] Erection is largely a parasympathetic response, so the sympathetic action of pseudoephedrine may serve to relieve this condition. Pseudoephedrine is an alpha-agonist agent that exerts a constriction effect on smooth muscle of corpora cavernosum, which in turn facilitates venous outflow. Pseudoephedrine is no longer available in some countries.

For those with ischemic priapism, the initial treatment is typically aspiration of blood from the corpus cavernosum.[3] This is done on either side.[3] If this is not sufficiently effective, then cold normal saline may be injected and removed.[3]

If aspiration is not sufficient, a small dose of phenylephrine may be injected into the corpus cavernosum.[3] Side effects of phenylephrine may include: high blood pressure, slow heart rate, and arrhythmia.[3] If this medication is used, it is recommended that people be monitored for at least an hour after.[3] For those with recurrent ischemic priapism, diethylstilbestrol (DES) or terbutaline may be tried.[3]

Distal shunts, such as the Winter's, involve puncturing the glans (the distal part of the penis) into one of the cavernosa, where the old, stagnant blood is held. This causes the blood to leave the penis and return to the circulation. This procedure can be performed by a urologist at the bedside. Winter's shunts are often the first invasive technique used, especially in hematologically induced priapism, as it is relatively simple and repeatable.[16]

Proximal shunts, such as the Quackel's, are more involved and entail operative dissection in the perineum where the corpora meet the spongiosum while making an incision in both and suturing both openings together.[17] Shunts created between the corpora cavernosa and great saphenous vein called a Grayhack shunt can be done though this technique is rarely used.[18]

As the complication rates with prolonged priapism are high, early penile prosthesis implantation may be considered.[3] As well as allowing early resumption of sexual activity, early implantation can avoid the formation of dense fibrosis and, hence, a shortened penis.

In sickle cell anemia, treatment is initially with intravenous fluids, pain medication, and oxygen therapy.[19][3] The typical treatment of priapism may be carried out as well.[3] Blood transfusions are not usually recommended as part of the initial treatment, but if other treatments are not effective, exchange transfusion may be done.[19][3]

The name comes from the Greek god Priapus (Ancient Greek: Πρίαπος), a fertility god, often represented with a disproportionately large, permanent erection.