Priapism

INTRODUCTION — 

The term "priapism" is derived from Priapus, the Greek god of fertility, gardening, and lust who is typically depicted with a massive phallus [1]. Priapism is defined as a persistent erection of the penis or clitoris that is not associated with sexual stimulation or desire. The focus of this topic is penile priapism, which has been found to adversely affect quality of life, sexual function, and physical wellness [2].

Priapism is relatively rare but can occur in all age groups and is particularly common in patients with sickle cell disease. It is classified as ischemic or nonischemic. Ischemic priapism is a urologic emergency, whereas nonischemic priapism is usually self-limited.

This topic reviews the epidemiology, pathophysiology, diagnosis, and management of penile priapism. Issues related to priapism in sickle cell disease are addressed separately. (See "Priapism and erectile dysfunction in sickle cell disease".)

DEFINITION — 

While there is no uniform temporal definition for priapism, most studies describe priapism as an erection lasting more than four hours, unrelated to sexual stimulation. Erection present for less than four hours is sometimes termed "prolonged erection." In clinical practice, symptom duration and classification by time course are less important than the presence of pain; many clinicians diagnose priapism and initiate treatment for erections lasting more than two hours, especially if pain is present. Because the evaluation and management of prolonged erection are similar to that of priapism, we refer only to priapism in this topic.

EPIDEMIOLOGY — 

Priapism is relatively uncommon. In a study of emergency department visits between 2006 and 2009 in the United States, there were 32,462 visits for priapism, which corresponded to an incidence of 0.73 per 100,000 men per year [3]. Priapism can be seen in any age group. However, there is a bimodal peak distribution of incidence, occurring between 5 and 10 years in children and 20 to 50 years in adults [4]. While most cases are idiopathic, the most commonly identified cause of priapism in adults is medication use, especially with intracavernosal injections for erectile dysfunction, accounting for 25 percent of cases [5].

ETIOLOGIES AND PATHOPHYSIOLOGY — 

Penile erection begins with the relaxation of the smooth muscle of cavernosal arteries and tissue, leading to increased arterial inflow and decreased venous outflow (figure 1). As intracorporal pressure rises to mean arterial pressure, the inflow of blood ceases. Priapism generally involves the corpora cavernosa only, although occasionally the corpus spongiosum and the glans penis are also affected [6].

Priapism is traditionally categorized into ischemic or nonischemic subtypes based on the presence of a compartment syndrome. These subtypes assist with identifying etiology and guiding management (table 1).

Ischemic priapism — Ischemic, or low-flow, priapism (also known as anoxic or veno-occlusive priapism) is the most common form of priapism. In ischemic priapism, failure of detumescence due to impaired relaxation of cavernosal smooth muscle results in a compartment syndrome and subsequent prolonged erection [7-9]. The cavernous tissue develops increasing hypoxia and acidosis as a result [10].

●Associated clinical conditions – Ischemic priapism is most commonly associated with sickle cell disease; it may also present alongside other hematologic conditions, including hematologic malignancy, thalassemia, polycythemia vera, and hypercoagulable states.

●Medication effect – Drug-induced ischemic priapism is most commonly caused by intracavernosal vasoactive injections for erectile dysfunction, including alprostadil, papaverine, phentolamine, and prostaglandin E1 [5].

Oral prescription medications may also cause ischemic priapism, including alpha-1 adrenergic antagonists, antidepressants, anticoagulants, and stimulant medications (table 1). Though priapism is a theoretical risk of phosphodiesterase 5 (PDE-5) inhibitors, PDE-5 inhibitor-induced priapism is a rare occurrence in clinical practice. For example, priapism from antipsychotics and trazodone was twice as frequently reported to the US Food and Drug Administration's adverse reporting system when compared with priapism from PDE-5 inhibitors [11].

Ischemic priapism is also associated with cocaine, alcohol, and cannabis use.

●Excess nitric oxide – Nitric oxide is an important mediator in the development of ischemic priapism, as it has a fundamental role in smooth muscle relaxation and promotion of the erectile response [12]. Excess nitric oxide activity, potentiated by a pre-existing hematologic condition or medication exposure (table 1), may therefore promote priapism. In patients with sickle cell disease, a regulatory defect in the nitric oxide pathway has been proposed [13]. (See "Priapism and erectile dysfunction in sickle cell disease", section on 'Pathophysiology and classification'.)

Nonischemic priapism — Nonischemic priapism (also known as high-flow, arterial, or congenital priapism) is rare. In contrast to ischemic priapism, in nonischemic priapism, although arterial inflow is unregulated, venous drainage in the penis is maintained, thereby avoiding a compartment syndrome. Etiologies are reviewed in the table (table 1) and below:

●Trauma – Nonischemic priapism may develop following penile or perineal trauma, including blunt trauma, as with bicycling or similar injury [14]. Nonischemic priapism may also result from urologic procedure. The onset of posttraumatic, nonischemic priapism can occur up to 72 hours after injury.

●Congenital abnormality – Congenital anatomic abnormalities of the penis, including cavernous arterial fistulas, pseudoaneurysm, and congenital arterial malformations, may predispose to the development of nonischemic priapism through similar mechanisms of increased cavernosal artery inflow.

●Adverse effect of intracavernosal injection – While intracavernosal injection is most frequently associated with ischemic priapism, nonischemic priapism from intracavernosal injection has been reported [15]. As with other presentations of priapism, chronicity, pain, rigidity, and cavernosal blood gas analysis assist with differentiating nonischemic from ischemic priapism. (See 'Distinguishing ischemic and nonischemic priapism' below.)

●Acute spinal cord injury – Nonischemic priapism also occurs as a result of acute, traumatic spinal cord injury, due to loss of sympathetic input and unopposed parasympathetic stimulation of penile arterial inflow [16]. (See "Acute traumatic spinal cord injury", section on 'Clinical presentation'.)

In rare circumstances, nonischemic priapism may convert to ischemic priapism if venous outflow becomes obstructed during the course of the condition [17].

CLINICAL MANIFESTATIONS — 

The presentation of priapism varies by type.

●Ischemic priapism – The vast majority of patients present with ischemic priapism. The compartment syndrome of ischemic priapism results in significant penile pain, due to anoxic tissue damage. The penis is fully rigid and extremely tender, especially along the corpus cavernosum. Patients may have a history of sickle cell disease, thalassemia, hypercoagulable state, or hyperviscosity syndrome; they may also report recent exposure to medications and substances that predispose to ischemic priapism (table 1). In rare cases, ischemic priapism can present with penile gangrene, resulting in necrosis of the entire penis [18]. If untreated, ischemic priapism may result in permanent erectile dysfunction (algorithm 1).

Recurrent priapism is a rare form of ischemic priapism in which episodes of priapism with spontaneous tumescence occur with increasing frequency, typically in patients with a history of sickle cell disease. (See 'Recurrent priapism' below.)

●Nonischemic priapism – Nonischemic priapism is less common. In these patients, the corpus cavernosum is not fully rigid, pain is mild, and palpation does not exacerbate pain. Because symptoms are milder than with ischemic priapism, patients with nonischemic priapism may present for evaluation much later in the course of the condition. Patients may have a recent history of perineal trauma or urologic procedures. Anatomic abnormalities, including cavernous arterial fistula, pseudoaneurysm, or congenital arterial malformation, predispose to the condition. Nonischemic priapism usually resolves spontaneously (algorithm 1).

DIAGNOSTIC EVALUATION

Establishing the presence of priapism — Priapism is a clinical diagnosis made based on visual inspection of the erect penis in the setting of a history of persistent erection in the absence of sexual excitation [5]. There is no uniform temporal definition; though many studies define priapism as an unwanted erection lasting more than four hours, we diagnose priapism and initiate treatment for erections lasting more than two hours, especially if pain is present, as this suggests ischemic priapism. (See 'Distinguishing ischemic and nonischemic priapism' below.)

Distinguishing ischemic and nonischemic priapism — A key objective of the diagnostic evaluation is differentiating ischemic and nonischemic priapism, as delayed treatment of ischemic priapism can lead to irreversible tissue damage and erectile dysfunction. (See 'Etiologies and pathophysiology' above.)

History — The history should focus on the nature and timing of the onset of priapism, prior episodes, past medical history, and medication history, including use of recreational drugs. A fully erect, intensely painful priapism of acute onset is consistent with ischemic priapism. A semiflaccid priapism of gradual onset is consistent with nonischemic priapism. Additional distinguishing features are reviewed in the algorithm (algorithm 1).

Other historical features may suggest ischemic versus nonischemic priapism:

●Preceding trauma related to urologic procedures or blunt trauma, as with bicycling or other sports injury, commonly precedes nonischemic priapism.

●Recurrent, unwanted erections of varying duration with intervening periods of spontaneous detumescence suggest recurrent or "stuttering" priapism, which is an uncommon, variant form of ischemic priapism. (See 'Recurrent priapism' below.)

Physical examination — The genitalia, perineum, and abdomen should be carefully examined for penile rigidity and signs of trauma or malignancy (figure 1). Ischemic priapism presents with a fully rigid erection. The erection associated with nonischemic priapism is typically semiflaccid (algorithm 1).

With both etiologies of priapism, penile examination reveals engorged corpora cavernosa, but in contrast to normal erections, the corpus spongiosum and glans penis may remain flaccid (figure 1).

Palpation of the corpus cavernosum exacerbates pain in ischemic priapism. With nonischemic priapism, palpation does not worsen pain, and the discomfort is generally mild.

Cavernous blood gas analysis — Cavernosal aspiration and blood gas analysis distinguish between ischemic and nonischemic priapism. The procedure is typically performed in the emergency department setting and should be pursued in all patients presenting with priapism, when available. Exceptions include priapism related to known sickle cell disease, because of the high likelihood of ischemic priapism, and when the priapism subtype is unequivocally clear from the history and examination (algorithm 1) [19]. (See "Overview of the clinical manifestations of sickle cell disease", section on 'Priapism'.)

●Procedure – A small caliber needle (eg, 19- to 21-gauge) is used to aspirate 3 to 5 mL of blood from one side of the corpus cavernosum. The sample should be sent for blood gas analysis.

●Gross inspection – Dark, viscous blood is suggestive of ischemic priapism, whereas red, oxygenated blood is consistent with nonischemic priapism.

●Interpretation of results – Cavernosal blood gas analysis with hypoxemia, hypercarbia, and acidemia (partial pressure of oxygen [PO₂] ≤40 mmHg, partial pressure of carbon dioxide [PCO₂] ≥60 mmHg, pH ≤7.25) confirms ischemic priapism. By contrast, blood gas analysis with normal levels of oxygen, carbon dioxide, and pH (PO₂ ≥60 mmHg, PCO₂ ≤40 mmHg, pH >7.25) is consistent with nonischemic priapism. In the normal, flaccid penis, cavernous blood gas levels are similar to mixed venous blood (PO₂ approximately 40 mmHg, PCO₂ approximately 50 mmHg, pH approximately 7.35).

When ischemic priapism is confirmed by evaluation and cavernosal blood gas analysis, additional intracavernosal injections are indicated for management. (See 'Initial therapy with intracavernosal injection and aspiration' below.)

Additional evaluation in selected patients

Laboratory testing — No laboratory tests are required in the initial evaluation and management of acute priapism. Blood tests should be performed based on clinical concern for an underlying condition. A complete blood count may suggest anemia or hematologic malignancy. Reticulocyte count, lactate dehydrogenase, and hemoglobin analysis are indicated when sickle cell disease or trait, thalassemia major, or leukemia is suspected. In sickle cell disease, the peripheral blood smear may identify sickled red cells or Howell-Jolly bodies, reflecting hyposplenia. (See "Diagnosis of sickle cell disorders".)

Urine toxicology should be performed if drug-induced priapism is suspected. Usual doses of several classes of psychiatric drugs, including trazodone and selective serotonin reuptake inhibitors, may also cause priapism (table 1) [20-22].

Doppler ultrasonography — When available, we use penile Doppler ultrasonography to distinguish ischemic and nonischemic priapism when cavernosal aspiration and blood gas analysis are not available or when the priapism subtype remains indeterminate after initial evaluation. Minimal or absent blood flow with Doppler ultrasonography is observed in the cavernosal arteries in ischemic priapism, whereas normal to high blood flow is observed in nonischemic priapism [23]. Ultrasonography may also assist with confirming the resolution of priapism after phenylephrine injection (algorithm 1). (See 'Repeat injection until detumescence' below.)

Doppler ultrasound can also detect cavernous arterial fistula, pseudoaneurysm, or other anatomic abnormalities.

DIFFERENTIAL DIAGNOSIS — 

Other conditions that result in penile tumescence include Peyronie's disease, urethral foreign body, penile surgical implant, and erection from sexual arousal. History and examination easily distinguish these from priapism.

MANAGEMENT — 

Our approach to managing priapism (algorithm 1) is consistent with recommendations from the American Urological Association [19,24]. Key management decisions include differentiating between ischemic and nonischemic priapism, urgent management of ischemic priapism, and outpatient management of nonischemic priapism.

Management of priapism in individuals with sickle cell disease is discussed separately. (See "Priapism and erectile dysfunction in sickle cell disease", section on 'Ischemic priapism: Acute management'.)

Ischemic priapism — Management of ischemic priapism should include emergency care and urgent urologic consultation, as rapid detumescence is required to optimize the preservation of erectile function. In many locations, emergency personnel may perform initial triage, cavernosal blood gas analysis, aspiration, and injection based on the availability of urologic specialists [25].

Initial therapy with intracavernosal injection and aspiration — When ischemic priapism is confirmed by cavernosal blood gas analysis, we treat promptly with cavernosal injection. We perform a dorsal penile block before intervention for pain control. When priapism has been present for greater than four hours (and less than 24 hours), we perform aspiration along with injection. For patients presenting with ischemic priapism of prolonged duration (eg, ≥24 hours), we prefer surgical intervention as initial therapy. (See 'Surgery for refractory or prolonged priapism' below.)

●Pain control with a penile block – Prior to aspiration or irrigation, we inject 2 to 4 mL of 1% lidocaine using a 25-gauge needle at the 2 and 10 o'clock position at the base of the penis to minimize discomfort.

●Aspiration for priapism lasting 4 to 24 hours – We perform aspiration prior to phenylephrine injection for priapism lasting more than four hours. Using a nonheparinized, 19-gauge butterfly needle, approximately 5 mL of blood should be aspirated to decompress the corpora. If aspiration is difficult, irrigation with 5 mL of normal saline may be added to mobilize clotted blood.

For priapism of less than four hours' duration, injection may be performed without advance aspiration, as there is a lower likelihood of clotted blood.

●Phenylephrine injection for all patients – We perform phenylephrine injection for all cases of ischemic priapism unless the overall duration is ≥24 hours. (See 'Surgery for refractory or prolonged priapism' below.)

•Preparation – Phenylephrine is diluted with normal saline to a final concentration of 100 to 500 mcg/mL.

•Injection – Using a 19-gauge butterfly needle, approximately 1 mL of diluted phenylephrine (as above) is injected into one side of the corpus cavernosum. Lower concentrations and smaller volumes may be appropriate for patients with severe cardiovascular disease. (See 'Monitoring for adverse effects' below.)

•Postprocedure observation – The patient should be observed for five minutes after injection for detumescence and improvement in pain, which indicate resolution of priapism. Penile edema and/or partial erection may persist and do not necessarily indicate unresolved priapism. In cases of uncertainty, detumescence may be verified with repeat cavernosal aspiration showing improved oxygenation or ultrasonography demonstrating restoration of blood flow. (See 'Cavernous blood gas analysis' above.)

Sympathomimetics induce contraction of the cavernous smooth muscle and thus permit venous outflow. Resolution of priapism has been reported in 43 to 81 percent of patients who received intracavernosal sympathomimetic medication versus 24 to 36 percent of patients receiving aspiration alone [26]. In another study, 86 percent of patients had successful detumescence with the use of intracavernous high-dose phenylephrine in the treatment of ischemic priapism over a five-year period at a single institution [27]. The risk of post-priapism erectile dysfunction is also lower with sympathomimetic use.

Phenylephrine, a pure alpha-adrenergic agonist, is the preferred sympathomimetic because of its minimal risk of cardiovascular side effects compared with other sympathomimetic medications, such as epinephrine, norepinephrine, and ephedrine [19]. Although large trial data are lacking, several small, observational studies demonstrate prompt resolution of priapism with phenylephrine intracavernosal injection [28-31].

Monitoring for adverse effects — We advise blood pressure monitoring for all patients and cardiac monitoring for patients with a history of cardiovascular disease. Phenylephrine toxicity includes both alpha-adrenergic-mediated hypertensive effects and beta-adrenergic-mediated inotropic and chronotropic effects, including acute hypertension, headache, and cardiac arrhythmia.

Repeat injection until detumescence — If priapism persists after the initial phenylephrine injection, repeat injection is indicated. A 1 mL intracavernous injection of diluted phenylephrine solution may be administered every three to five minutes for up to one hour until detumescence is achieved [26]. In refractory cases in which there is minimal improvement, aspiration with or without saline irrigation may be added to subsequent injections [19].

If detumescence is not achieved after one hour of intracavernosal treatment, including phenylephrine, aspiration, and saline irrigation, surgical intervention is indicated. Priapism of longer duration (≥4 hours) is associated with prolonged ischemia and decreased efficacy of phenylephrine; in such patients, it is reasonable to stop phenylephrine if no improvement is noted after two to three rounds of aspiration and injection and proceed directly to urologic consultation. (See 'Surgery for refractory or prolonged priapism' below.)

Surgery for refractory or prolonged priapism

Indications

●Nonresponse to intracavernosal injection – If ischemic priapism persists beyond one hour of intracavernosal injection and aspiration, urgent urologic surgery is indicated. For patients with priapism of longer duration (≥4 hours), earlier surgical intervention may be appropriate. (See 'Repeat injection until detumescence' above.)

●Priapism of prolonged duration (≥24 hours) – If priapism has been present for ≥24 hours at presentation, intracavernosal injection may be bypassed in favor of shunt surgery as first-line therapy, as detumescence with phenylephrine is unlikely [32,33].

Observation with pain control and outpatient urology follow-up is a reasonable alternative, as the likelihood of preservation of erectile function is low given the duration of ischemia [24]. The decision between surgery and observation should be made through shared decision-making with the patient, accounting for the duration of priapism, baseline sexual function, and comorbidities.

Procedure — Surgical intervention involves the creation of a shunt with or without a penile prosthesis. Using various approaches, a surgical fistula is created between the corpus cavernosum and the glans penis or one of the penile veins to decompress the compartment syndrome and trapped blood within the corpora. Several observational studies have shown some efficacy of shunt surgery in relieving ischemic priapism, with limited preservation of erectile function [34-37]. Some patients may require multiple surgical procedures.

Penile prosthesis implantation at the time of shunt surgery may be offered for patients with late presentation or prolonged duration (≥24 hours) or in patients for whom the prognosis for sexual function is otherwise poor (eg, older patients, patients with poor baseline erectile function, and patients with cardiovascular disease or other chronic comorbidities) [19,38-40].

Prosthesis implantation increases the likelihood of return to sexual activity and reduces fibrosis of corpora cavernosum smooth muscle, penile shortening, and curvature in cases of prolonged refractory priapism [39,41-43]. In such patients, gadolinium-enhanced, high-definition magnetic resonance imaging of the penis can be useful in determining whether acute penile prosthesis implantation would be beneficial, as it is highly sensitive in detecting necrosis of the cavernosal smooth muscle and corporal bodies [44,45].

A penile prosthesis may also be pursued electively for erectile dysfunction after several prolonged priapism episodes [19,39]. Further details regarding preoperative preparation, candidate selection, and prosthesis types are discussed separately. (See "Surgical treatment of erectile dysfunction".)

Nonischemic priapism

●Primary conservative management – Nonischemic priapism is a nonurgent condition that does not require specific intervention and can be managed expectantly as an outpatient; spontaneous resolution within several hours to up to three days has been reported in 62 percent of untreated cases (algorithm 1) [16,26].

Aspiration and injectable sympathomimetic agents have not been shown to be effective and risk unnecessary cardiovascular side effects [4,5]. The risk of short-term complications in patients with nonischemic priapism appears to be small, and follow-up with a urologist within approximately four weeks is appropriate unless the patient is severely bothered by the tumescent penis.

●Evaluation for symptoms lasting longer than four weeks – For patients with persistent nonischemic priapism beyond four weeks, a Doppler ultrasound should be performed to assess for a fistula or other anatomic abnormality.

●Elective surgical options – If a fistula is identified, percutaneous fistula embolization using absorbable gelatin powder, metallic coils, or autologous clot may be offered. In several observational studies, percutaneous embolization has resulted in the relief of nonischemic priapism, with preservation of erectile function [41,42,46]. Resolution of nonischemic priapism with embolization can be as high as 89 percent [47].

If initial embolization fails, repeat angiographic embolization or open surgical ligation of the ruptured artery with the aid of intraoperative ultrasonography may be necessary. Relief of nonischemic priapism after failed embolization therapy has been reported with surgical ligation, with partial to full recovery of erectile function [48-50].

Embolization, surgery, and other interventions for nonischemic priapism carry a risk of erectile dysfunction and priapism recurrence and should be pursued electively through shared decision-making with the patient, accounting for duration of priapism, sexual function, comorbidities, and disruptiveness of symptoms [24].

FOLLOW-UP, PROGNOSIS, AND PREVENTION

●Follow-up – Following detumescence and resolution of priapism, patients with both ischemic and nonischemic priapism should follow up with urology to ensure resolution of symptoms and monitor for erectile dysfunction or other complications. (See "Evaluation of male sexual dysfunction".)

●Prognosis – In ischemic priapism, the duration of priapism is strongly associated with subsequent erectile dysfunction. Significant structural changes in the cavernous smooth muscle can be seen after 12 hours' duration of priapism [10,51-53]. Irreversible damage has been identified after greater than 24 hours of priapism, including necrosis of cavernosal smooth muscle and endothelial cells, fibroblast proliferation, and fibrosis of the corpus cavernosa. Ninety percent of patients with an ischemic priapism lasting greater than 24 hours do not regain the ability to have sexual intercourse [54]. In contrast, early relief of priapism with the return of normal flaccidity is not likely to be associated with long-term sequelae.

●Prevention – Patients whose priapism was the result of erectile dysfunction treatment (intracavernosal injections, etc) may need their treatment revised. In cases with associated conditions (eg, sickle cell disease, hematologic malignancy), the underlying condition should be addressed to reduce the likelihood of future episodes. (See 'Recurrent priapism' below.)

For priapism not associated with an underlying condition or medication, optimal strategies to prevent subsequent episodes are unknown. Phosphodiesterase 5 inhibitors, oral baclofen, dutasteride, ketoconazole with prednisone, pseudoephedrine, cyproterone acetate, and aspirin have been used in case reports with some evidence of efficacy [55-60].

RECURRENT PRIAPISM

●Definition – Recurrent priapism (also known as "stuttering priapism") is an uncommon form of ischemic priapism, usually occurring in men with sickle cell disease. In recurrent priapism, the patient experiences recurrent ischemic episodes, with any frequency or over any period of time, with or without meeting the four-hour time criteria for acute priapism. These episodes may become longer in duration and more frequent, eventually leading to a full-blown ischemic priapism event. The pathophysiology of this type of priapism is not fully understood. A mechanism based on the dysregulation of nitric oxide and phosphodiesterase 5 (PDE-5) in the corporal smooth muscle has been proposed [13,61-64].

●Management – Acute episodes should be treated as individual ischemic priapism events. Anticipatory guidance regarding the escalating nature of each event should be discussed, including the importance of prompt emergency care to avoid refractory priapism requiring surgery.

●Preventive treatment – Patients with sickle cell disease or other hematologic disorders also benefit from additional therapies to prevent future episodes. (See 'Ischemic priapism' above and "Priapism and erectile dysfunction in sickle cell disease".)

Several preventive treatments have been proposed. Because these treatments are investigational, we discuss these with prospective patients using a shared decision-making approach, acknowledging the potential risks and limited data. In one study of 24 patients with idiopathic and sickle cell-associated recurrent priapism, sildenafil 25 mg daily decreased priapism duration and priapism frequency and reduced emergency department visits at three-month follow-up [65]. Larger studies are necessary, as a clinical history of ischemic priapism is otherwise a contraindication to treatment with PDE-5 inhibitors. Hormonal manipulation with ketoconazole and cyproterone acetate has also been investigated in small studies and case reports with variable results [55,66,67].

Additional preventive strategies for priapism in patients with sickle cell disease are discussed separately. (See "Priapism and erectile dysfunction in sickle cell disease", section on 'Prevention'.)

Rarely, nonischemic priapism may present with features of recurrent priapism, including sleep-related painful erections and periodic priapism as a manifestation of chronic spinal cord injury, among other conditions [68]. Though there are limited data on the management of recurrent nonischemic priapism, because there is no underlying ischemia, emergent intervention is not indicated, and observation is appropriate [24] (see 'Nonischemic priapism' above). Case reports suggest intrathecal and oral baclofen may be beneficial in reducing the duration and frequency of spinal cord injury-related periodic priapism [69,70].

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Male sexual dysfunction".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Priapism (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Definition and clinical features – While there is no uniform, temporal definition for priapism, most studies describe priapism as an unwanted, painful erection lasting more than four hours, unrelated to sexual stimulation. In clinical practice, symptom duration and classification by time course are less important than the presence of pain; we diagnose priapism and initiate treatment for erections lasting more than two hours, especially if pain is present, as this suggests ischemic priapism.

Ischemic priapism usually presents with a painful, rigid erection. If untreated, it may result in permanent erectile dysfunction. Nonischemic priapism is less common. Patients present after trauma with a semiflaccid erection that is usually painless and resolves spontaneously. (See 'Etiologies and pathophysiology' above.)

●Causes – Priapism has been associated with several medications and diseases, including sickle cell disease (table 1). Issues related to priapism in sickle cell disease are addressed separately. (See "Priapism and erectile dysfunction in sickle cell disease".)

●Evaluation – The primary objective is to differentiate ischemic and nonischemic priapism. Key features of ischemic priapism include rapid onset, severe pain, and fully rigid erection, usually associated with underlying sickle cell or hematologic condition, intracavernosal injection, or other medication exposure. Nonischemic priapism is minimally painful, semiflaccid, and of subacute onset (algorithm 1 and table 1). (See 'Diagnostic evaluation' above.)

Cavernous blood gas analysis distinguishes between ischemic and nonischemic priapism and should be performed as part of the initial evaluation (algorithm 1). Exceptions include priapism related to known sickle cell disease, because of the high likelihood of ischemic priapism, and when the priapism subtype is unequivocally clear from the history and examination. (See 'Cavernous blood gas analysis' above.)

No laboratory tests are required in the initial management of acute priapism. However, if specific underlying conditions (eg, hematologic abnormality or drug-induced priapism) are suspected (table 1), additional tests may be performed. (See 'Laboratory testing' above.)

Doppler ultrasonography is useful in situations where cavernosal blood gas analysis is not available or the priapism subtype remains indeterminate after initial evaluation. Ultrasound is also used to confirm the resolution of priapism after intervention. (See 'Doppler ultrasonography' above.)

●Management

•Ischemic priapism of <24 hours' duration – In patients with ischemic priapism presenting within 24 hours, we suggest intracavernosal injection with a sympathomimetic agent (eg, phenylephrine) rather than cavernosal aspiration alone (Grade 2C). For priapism duration >4 hours, we perform cavernosal aspiration first. Sympathomimetics are associated with more rapid resolution of priapism and less erectile dysfunction; we typically use phenylephrine, as it has fewer side effects than other agents.

If priapism persists after the initial phenylephrine injection, a repeat injection may be given every three to five minutes for up to one hour. Aspiration and saline irrigation may also be added if not already performed. (See 'Initial therapy with intracavernosal injection and aspiration' above.)

Patients who do not achieve detumescence after one hour of medical therapy require surgery.

•Ischemic priapism of ≥24 hours' duration – For patients who present with prolonged (≥24 hours) priapism, we suggest surgery (Grade 2C). However, observation with pain control and outpatient urology follow-up is a reasonable alternative as the likelihood of preservation of erectile function is low given the duration of ischemia. (See 'Surgery for refractory or prolonged priapism' above.)

•Nonischemic priapism – In patients with nonischemic priapism, we suggest conservative management rather than a specific intervention (Grade 2C). Nonischemic priapism can last hours to days and resolves spontaneously in most patients. (See 'Nonischemic priapism' above.)

●Prognosis – Following detumescence and resolution of priapism, patients with both ischemic and nonischemic priapism should be seen in follow-up with urology to ensure resolution of symptoms and monitor for erectile dysfunction or other complications. In ischemic priapism, the duration of priapism is strongly associated with subsequent erectile dysfunction. (See 'Follow-up, prognosis, and prevention' above.)