Rigi10™ Malleable Penile Prosthesis
Also Known As
Non-ischemic priapism, arterial priapism, high-flow priapism, traumatic priapism, red priapism.
Definition
High-flow priapism, also known as non-ischemic or arterial priapism, is a type of persistent penile erection that occurs in the absence of sexual stimulation and is caused by unregulated, excessive arterial blood flow into the corpora cavernosa, the erectile tissues of the penis.¹ It is distinct from ischemic (low-flow) priapism in that the blood within the corpora cavernosa remains well-oxygenated, and therefore, tissue ischemia (damage due to lack of oxygen) does not typically occur.² Consequently, high-flow priapism is usually not painful.¹
The underlying mechanism often involves the formation of an abnormal connection, or fistula, between an artery and the sinusoidal spaces within the corpora cavernosa. This fistula allows arterial blood to bypass the normal regulatory mechanisms that control penile blood flow, leading to a sustained erection that is often not fully rigid but is persistent.² High-flow priapism most commonly develops following direct trauma to the penis or perineum, which can damage a cavernosal artery and lead to fistula formation.¹ The onset can be immediate or delayed, sometimes appearing days or even weeks after the initial injury.¹ While it is a less common form of priapism compared to the ischemic type, it requires accurate diagnosis and appropriate management to prevent long-term complications, although it is not typically considered a urological emergency in the same way as ischemic priapism.²
Clinical Context
High-flow (non-ischemic) priapism is typically encountered in clinical settings following trauma to the penis or perineum, which results in the formation of an arteriovenous fistula and unregulated arterial inflow to the corpora cavernosa.¹ The presentation is often delayed, occurring days or weeks after the inciting injury.¹ Unlike ischemic priapism, it is generally not painful and the penis is often not fully rigid, but the erection is persistent.²
The diagnosis is confirmed through a combination of history, physical examination, and specialized investigations. Penile blood gas analysis will typically show bright red (oxygenated) blood, consistent with arterial blood, contrasting with the dark, hypoxic, and acidotic blood found in ischemic priapism.² Color Doppler ultrasonography of the penis and perineum is the gold standard diagnostic tool; it can identify the characteristic high-flow state and often visualize the site of the arteriocavernosal fistula.²
Management of high-flow priapism is often initially conservative, as spontaneous resolution can occur in a significant number of cases, particularly if the fistula is small.¹ Observation with reassurance and reassessment after a period (e.g., four weeks as suggested by AUA/SMSNA guidelines) is a common first step.² If the priapism persists or if the patient desires more immediate resolution, intervention is considered.²
Patient selection for intervention involves counseling about the risks and benefits. The primary treatment modality is selective arterial embolization, performed by an interventional radiologist.² This procedure aims to occlude the fistula, thereby stopping the unregulated arterial inflow. Materials used for embolization can be absorbable (e.g., gelatin sponge) or non-absorbable.² Success rates for embolization are generally high, but potential complications include erectile dysfunction, recurrence of priapism (if the fistula recanalizes or new ones form), and failure to correct the priapism.² If an initial embolization attempt with resorbable materials is unsuccessful, a repeat procedure with non-absorbable materials may be considered.² Surgical ligation of the fistula is an alternative but is typically reserved for cases where embolization fails or is not feasible.²
Expected outcomes after successful treatment are generally good, with resolution of the priapism. However, the risk of subsequent erectile dysfunction is a key consideration, particularly related to the underlying trauma or the interventional procedure itself.² Close follow-up is necessary to monitor for resolution and any potential complications.