Pathophysiology and Non-Surgical Management
Priapism describes a persistent erection arising from dysfunction of the mechanisms regulating penile tumescence and flaccidity. The erection of priapism is typically not the result of sexual excitement and, if associated with erotic stimulation, lasts well beyond the original stimulus and is not relieved by orgasm or ejaculation.
A diagnosis of priapism is a matter of urgency requiring identification of the underlying etiology because prompt therapy may successfully alleviate the condition and minimize potential morbidities.
Ischemic or low-flow priapism accounts for more than 95 % of allpriapism episodes. Ischemic priapism is typically associated with a rigid and painful erection with stasis of blood, and which is not relieved by ejaculation or orgasm. (Stuttering or intermittent priapism is a recurrent form of low-flow priapism whereby the painful erections occur repeatedly with periods of intervening detumescence.)
Sickle cell disease and other hematologic abnormalities are most often associated with low-flow priapism. Various drugs may precipitate an episode of ischemic priapism, such as trazodone, antihyperten-sive agents, alcohol, marijuana, cocaine, as well as intracavernous vasoactive agents such as papaverine, prostaglandinEl, phentolamine and others.
Physical examination typically reveals painful or tender complete rigidity of the corpus cavernosa, sparing the glans and spongiosum. Abdominal and genital examination may reveal evidence of prior trauma or malignancy. Laboratory evaluation, including complete blood count (CBC) and white blood count (WBC), to rule out infection and hematologic abnormalities, reticulocyte counts, hemoglobin electrophoresis when indicated, drug screening (e.g. cocaine and its metabolites), corporal blood gas testing, and duplex ultrasound (if available), should be performed. Cavernous blood gas findings in ischemic priapism may include p02 < 30mmHg, pC02 > 60mmHg, and pH < 7.25. Cavernous blood gas findings similar to arterialblood are found in patients with non-ischemic priapism.
Table Key clinical findings in priapism. Adapted from AUA Guidelines on Management of Priapism.
|Findings||Ischemic priapism||Non-ischemic priapism|
|Corpora cavernosa fully rigid||Usually||Seldom|
|Abnormal cavernosal blood gas||Usually||Seldom|
|Blood abnormalities and malignancy||Sometimes||Seldom|
|Recent intracorporal injection||Sometimes||Seldom|
|Chronic, well-tolerated tumescence||Seldom||Usually|
Ischemic Priapism: Treatment
In general, immediate surgical intervention should be avoided while less invasive and often successful alternatives are first attempted, especially in cases of less than six hours duration. Previous recommendations for priapism episodes associated with sickle cell disease included prolonged treatments with oxygen, analgesics, and intravenous hydration, prior to intracorporal therapy or surgical intervention, due to the often repetitive and self-limiting nature of their priapism episodes. Unfortunately, this regimen is often unsuccessful and results in an increased rate of corporal fibrosis and erectile dysfunction, and is no longer recommended. In very select cases of priapism associated with sickle cell disease, the successful use of exchange transfusions to reduce the fraction of abnormal HbS hemoglobin, and hyper-transfusion with packed red blood cells to double the hematocrit and diminish the fraction of HbS present, has been described to achieve detumescence. Early hemoglobin electrophoresis to determine the fractional percentage of HbS present serves as a useful guideline for monitoring subsequent transfusion therapy. As with any transfusion of blood or blood products, the associated risks, including disease transmission and HIV, should be discussed with the patients prior to transfusion, and the potential benefits weighed against the disadvantages.
The AUA guidelines committee recommends the use of phenylephrine, an alpha-selective adrenergic agonist with no indirect neurotransmitter-releasing action. This agent minimizes the risk of cardiovascular side effects that are more commonly seen with other sympathomimetic agents. For intracavernosal use in adult patients, phenylephrine is diluted with normal saline to a concentration of 100 to 500 µg/mL. One ml injections are made every five minutes as needed, up to one hour. During treatment, patients should be observed for symptoms, such as acute hypertension, headache, reflex bradycardia, tachycardia, palpitations, and cardiac arrhythmia.
For children or those with severe cardiovascular disease, lower doses are recommended. In patients with severe cardiovascular disease, it is prudent to monitor blood pressure and pulse rate in a controlled surveillance setting.
The use of oral terbutaline, a beta-agonist, both for the preventive and active treatment of ischemic priapism has been suggested. However, there are no studies to date demonstrating clear efficacy over placebo, and their use in the management of priapism is not recommended.
For patients with recurrent or “stuttering” priapism, a monthly regimen of gonadotropin-releasing hormone analogues can be effective in decreasing the occurrence of priapism. Likewise, the use of oral digoxin at therapeutic levels has been shown to be safe and efficacious for decreasing the frequency of recurrent priapism episodes while allowing for normal sexual function and libido.
Associated Issues of Ischemic Priapism
1 Persistence and recurrence despite active intervention.
2 Erectile dysfunction. It is estimated that more than 2 5 % of patients with priapism will have some degree of ED.
Non-lschemic (High Flow) Priapism
Non-ischemic or high-flow arterial priapism is a form of priapism typically caused by traumatic cavernosal artery laceration, or injury that enables unregulated flow of arterial blood directly into the lacunar spaces of the corpora, bypassing the protective, high-resistance helicine arterioles. This constant unregulated flow results in the pathognomonic arterial-lacunar fistula (ALF) of high-flow priapism.
The clinical characteristics of non-ischemic priapism typically include a pre-morbid history of trauma, delayed onset of priapism following the trauma, incomplete rigidity of the phallus compared to pre-morbid sexually-stimulated erectile rigidity, and a constant erection that is painless, non-tender, of persistent partial rigidity throughout the day and night, with the potential for increase to full rigidity with sexual stimulation. Although spontaneous resolution may occur, with non-ischemic priapism the painless, partial erection will often continue unless “active” intervention is performed.
Selective internal pudendal arteriography has been the mainstay of diagnostic and therapeutic maneuvers for arterial priapism. The pathognomonic arteriographic finding is of an arterial-lacunar fistula — a characteristic intracavernosal cone-shaped blush of contrast at the site of the cavernosal artery laceration.
Unfortunately, these therapies have had little success in reversing the high-flow priapism state and are currently not recommended by the AUA guidelines for priapism therapy.
The current standard of intervention remains selective internal pudendal arteriography with transcatheter autologous clot embolization. The goal of this therapy is to induce temporary occlusion of the cavernosal artery in order to allow the injured site to heal. The temporary nature of this occlusion allows for the subsequent reestablishment of physiologically-controlled normal cavernosal blood flow, with preservation of erectile tissue viability and normal long-term erectile function. This form of minimally-invasive intervention has a high probability for resolution of the priapism with restoration of erectile potency compared to more invasive techniques, including permanent coil embolization and surgical ligation of the cavernosal artery.
Studies comparing perineal duplex ultrasound and concomitantly preformed selective internal pudendal arteriography have revealed excellent sensitivity in detecting the arterial-lacunar fistula that is seenangiographically on ultrasound (12 of 12 cases). In both the selective internal pudendal arteriography and perineal duplex study, the arterial lacunar fistula was noted at the same location. In fact, in one reported case where physical examination suggested incomplete return to flaccidity and post-embolization due to recurrent fistula, the negative perineal duplex Doppler ultrasound study correctly predicted the final clinical outcome of complete priapism resolution and full erectile function. Therefore if the follow-up clinical examination is equivocal for recurrence of the arterial lacunar fistula, perineal duplex Doppler ultrasound may better predict the need for repeat arteriography and embolization.
The current algorithm for the management of non-ischemic priapism is seen in Fig. “Patient management algorithm based on study group data”. The algorithm emphasizes patient history, physical examination, pre-morbid and current erectile function status, and the use of perineal duplex Doppler ultra-sonography for initial identification of the pathognomonic arterial-lacunar fistula. If an “active” course of treatment is chosen, selective internal pudendal arteriography and embolization with autologous clot, with or without Gelfoam should be employed. While complete detumescence is ideally seen immediately following selective embolization, partial tumescence at this time may be related to longstanding edema, reinforcing the concept that physical examination alone cannot be used to determine the endpoint of treatment or as the sole means of follow-up evaluation. Serial perineal and penile duplex studies over the days and weeks post-embolization should be part of the overall regimen to assure adequate resolution of the arterial lacunar fistula. If further intervention is required, perineal duplex studies can reduce the reliance upon multiple subsequent angiographic procedures and their associated risks.
The medico-legal aspect of priapism and its associated diagnostic and therapeutic interventions remains important in our litigious society. The physician should explain to the patient the natural history of the disease and the extremely high risk of developing erectile dysfunction, early or late, despite active or no intervention. Discussion should include the advantages and potential disadvantages of the various
treatment alternatives, as well as the risks associated with no treatment at all. Documentation of this, in addition to any prior erectile dysfunction, and all counseling sessions, should be meticulous.
Selections from the book: “Standard Practice in Sexual Medicine”, edited by Hartmut Porst, Jacques Buvat, and The Standards Committee of the International Society for Sexual Medicine, 2006.