Penile Irrigation, Aspiration, and Vasoactive Injections for Priapism Treatment

Anatomy and Physiology

The basic structure of the penis is the key anatomy for intracorporal penile injections and aspiration. Superficially, the penis is covered by the skin and dartos fascia.[10] Beneath the dartos is the superficial dorsal vein.[10] Deep to that is Buck's fascia that surrounds 3 cylindrical structures and the dorsal neurovascular bundle.[10] The 3 cylindrical organs within the penis include the paired corpora cavernosa, which lie superiorly and laterally to the final cylinder, and the corpora spongiosum.[10]

These cylindrical organs perform distinct functions.[11] The corpora spongiosum surrounds and supports the urethra, preventing occlusion of the urethra during erection.[11] These structures remain flaccid during erections and priapism. In contrast, the paired corpora cavernosa are the erection bodies that fill with blood during an erection, causing the rigidity of the penis as their covering, the tunica albuginea, does not stretch.[11] As the corpora continue to fill with blood, they become stiff and rigid.[11] The erection bodies or corpora are connected by fenestrations that allow blood to flow freely between them.[10] 

Normal erection physiology begins with sexual stimulation, which causes relaxation of smooth muscles of the corpora via parasympathetic signals, leading to an increase in nitric oxide (NO) to cyclic guanosine monophosphate (cGMP) ratio.[11] These changes cause the cavernosal arterial system to dilate, increasing blood flow into the corpora while also decreasing outflow by compression of the subtunical venous plexus and the emissary veins.[11] When the penis reaches its erect state, the intracorporal pressure is around 100 mm Hg.[11][12] Detumescence begins with a decrease in the NO/cGMP ratio, stimulating contraction of smooth muscle, in turn triggering a decrease in pressure.[11] This process is likely due to decreased obstruction of venous outflow and reduction of the arterial flow back to baseline.[11][13][14]

Ischemic priapism is associated with little or no cavernosal venous outflow, which restricts arterial inflow, ultimately causing tissue ischemia, smooth muscle and endothelial tissue damage, and fibrosis or scarring.[1][6][7][15] Ischemic priapism results in limited oxygenated blood inflow and deoxygenated blood outflow.[1][6][8] This condition is believed to originate from the dysregulation of the NO/cGMP pathway, leading to decreased venous return.[1] There is stasis of blood within the corpora, which becomes thick and coagulates, preventing further venous outflow.[1] This stasis causes endothelial and smooth muscle damage, further preventing venous outflow and leading to fibrosis.[1][16] 

Nonischemic priapism is often secondary to trauma resulting in injury to the arterial system and fistula formation.[1][6] This injury causes unopposed arterial flow into the corpora but unrestricted venous outflow.[1][6] Treatment involves observation, selective or superselective embolization, or surgical ligation.[1][6][8][17]

Aspirated corporal blood gases can be used effectively to differentiate ischemic from high-flow priapism.[1]

• Ischemic priapism: pH <7.2, pO₂ <30 mm Hg, and pCO₂ >60 mm Hg.
• High-flow nonischemic priapism: pH >7.2, pO₂ >90 mm Hg, and pCO₂ <40 mm Hg.

Permanent ultrastructural changes to the corpora cavernosa begin after 14 hours.[15] The first noticeable change is trabecular interstitial edema, which is followed by the transformation of trabecular smooth muscle cells into fibroblasts.[15] After 24 hours, severe cellular damage with significant necrosis is found due to vascular stasis, prolonged deoxygenation, and ischemia.[15] After 48 hours, blood clots form within the corpora cavernosa, the endothelial lining is destroyed, and cavernosal smooth muscle cells have either transformed into fibroblasts or necrosed.[15] 

Indications

Penile irrigation, aspiration, and intracorporal injection therapy are indicated if a patient is experiencing ischemic priapism for less than 72 hours, and the erection has not resolved with other less invasive techniques.[1][18][19] Conservative treatments include increased physical activity, cold showers, application of ice, and various oral medications, including pseudoephedrine.[1] Oral terbutaline was frequently suggested in the past but is not currently recommended by the American Urological Association (AUA) or European Association of Urology (EAU) due to the lack of any proven efficacy.[8] Failure rates for such conservative measures are reported as high as 75%.[1]

Contraindications

An ischemic priapism time of greater than 72 hours is a relative contraindication, as injection and aspiration, even with pharmacological intracorporal phenylephrine injections, cannot preserve erectile function.[1][20] Patients with ischemic priapism with an erection of greater than 72 hours duration do not recover natural or normal erections.[1][20]

High-flow priapism, overlying penile cellulitis, and an uncorrected bleeding disorder are relative contraindications to performing penile injection and aspiration, as ischemic priapism is a medical emergency.[1]

Equipment

Required equipment for penile injection and aspiration includes:

• Anesthetic: 1% preservative-free lidocaine or 0.5% preservative-free bupivacaine with an 18-G needle to draw medication and a 25- to 30-G needle to administer the anesthetic as a ring or dorsal penile block
• Antimicrobial antiseptic preparation
• Blood gas syringe
• Dressings: Gauze and self-adherent wrap
• Empty syringes: 10, 20, and 30 mL
• Fenestrated drape
• Gauze sponges (4 × 4)
• Heparinized or normal saline flushes
• Large-bore butterfly needles (19 G is typically recommended)
• Phenylephrine solution: 100 to 500 µg/mL [21]
• Sterile basin for the collection of aspirated blood
• Sterile gloves

Personnel

Penile injection and aspiration procedures are generally performed in the emergency department by the on-call urologist or by a trained emergency physician. A nurse is recommended to be included as a chaperone for the procedure and to help facilitate the aspiration procedure. 

Preparation

Obtaining a detailed history and performing a thorough physical examination are essential before performing penile injection and aspiration, as they typically help identify the cause of priapism, allowing proper recommendations and long-term treatment.[1] The clinician should assess the duration of the erection, associated penile pain, history of perineal trauma, and any previous episodes of priapism.[1]

Obtaining a detailed history of medication and recreational drug use is also important. Any history of blood dyscrasias or cancers, including leukemia and sickle cell disease, should be obtained. Blood dyscrasias and cancers resulting in priapism may require exchange transfusions or leukapheresis, depending on the underlying condition.[3] 

The physical examination should include an abdominal assessment but should primarily focus on the genitalia. Blood pressure must also be evaluated, as treatment may cause significant elevations. The rigidity of the penis and glans needs to be noted. The tenderness of the penis to palpation requires assessment. If the penis is rigid and tender, this suggests ischemic priapism, where semi-rigid and less tender phallus palpation is suggestive of nonischemic (high flow) priapism.

An initial, less invasive option to differentiate ischemic from nonischemic priapism includes Doppler ultrasound. Ischemic priapism generally has minimal or absent blood flow on Doppler ultrasonography, whereas high-flow priapism has normal to high blood flow.[22]

Generally, a standard laboratory evaluation is required, including a complete blood count and a blood gas taken directly from the corpora cavernosa. A sickle cell test should be included if this disorder is suspected.[1] If the initial aspiration of corpora blood is dark and thick, this suggests ischemia, while brighter red blood suggests nonischemic high-flow priapism.[1] 

No imaging is acutely required, but if malignancy is suspected, a magnetic resonance imaging scan is the optimal modality for evaluation.[1] A penile Doppler can also be used to assess for elevated arterial flow in the setting of high-flow priapism.[23]

Phenylephrine is the preferred first-line vasoactive sympathomimetic agent utilized for the reversal of ischemic priapism by intracorporal injection due to its proven efficacy and overall safety compared to similar agents.[1][24]

The hospital pharmacy can prepare a 10- or 20-mL syringe with the desired phenylephrine concentration, such as 200 mcg/mL.[1] This concentration is commonly obtained by diluting 1 mL of 10 mg phenylephrine solution in 49 mL of normal saline.[1] Because preparation may take time, it is advisable to request the diluted medication from the pharmacy early.[1] Providing the pharmacy with the dilution formula beforehand can further facilitate the timely preparation of the drug.[1]

Technique or Treatment

Prepping and Draping

A long-acting parenteral analgesic, such as morphine or hydromorphone, can be administered, and procedural sedation and analgesia may also be considered.

The entire penis, including the base, is prepped with an antimicrobial or antiseptic solution, such as betadine or chlorhexidine. If neither is available, alcohol swabs may be used. A sterile field is created using towels, drapes, or a fenestrated dressing.

Anesthesia

Treatment begins with the administration of an anesthetic block, typically achieved through either a dorsal penile nerve block or a circumferential ring block.[1] A dorsal penile nerve block is performed using 1% lidocaine or 0.5% bupivacaine, preservative-free, and without epinephrine. Alternatively, a ring block may be administered at the base of the penis. 

The procedure involves the following steps:

• Cleanse the area at the base of the penis.
• Identify landmarks at the 10 and 2 o'clock positions at the base of the penile shaft.
• (Optional) Inject a superficial wheal of local anesthetic into the skin at the identified sites of butterfly needle insertion.
• Redirect and advance the needle toward the shaft to approximately 0.5 cm.
• Once the needle is within Buck's fascia, resistance is lost, which ensures that the neurovascular bundle has been reached.  
• Aspirate to ensure the needle tip is not within a blood vessel.
• Slowly inject 2 mL of the local anesthetic at each site. This dose should not exceed 4.5 mg/kg when dealing with pediatric patients.[25] 

Procedure

• Once the block has completely anesthetized the penis, a large-bore butterfly needle (≥19 G) is placed into the corpora cavernosus at a perpendicular angle to the penis (at the 2 to 3 o'clock or the 9 to 10 o'clock position) in the midshaft near the penile base.[1][19]
• Care should be taken not to violate the urethra, the dorsal penile neurovascular bundle, obvious large superficial veins, or puncture through to the contralateral corpora cavernosa.
• Only 1 side requires irrigation and aspiration because the corpora are connected with fenestrations and free passage of blood between them.
• A second, smaller butterfly needle (21 G) may optionally be used to facilitate the irrigation inflow, leaving the larger second butterfly for aspiration and outflow.
  • This second needle may be placed on either side since the 2 corpora freely communicate with each other. 
  • Placing it through the glans into the distal corpora cavernosa is an option that has the advantage of allowing any bleeding from the cavernosal puncture site to empty into the freely draining corpora spongiosum.
  • Limiting the number of punctures to the corpora decreases the risk of a penile hematoma later. 

• Once the needle has been placed, aspiration can be attempted using a 10- to 20-mL syringe (preferred), as larger syringes, such as 30 mL, are more challenging to manipulate and aspirate.
• Aspirated blood can be used for a blood gas determination, and the butterfly can be used for further irrigation and sympathomimetic (phenylephrine) drug administration.
• This vasoactive solution for intracorporal injections can be prepared by the pharmacy using 1 mL of 10 mg phenylephrine diluted in 49 mL of normal saline.[1]
• Aspiration is often unsuccessful because the blood has become coagulated, requiring irrigation with heparinized or normal saline. 
• After the injection of irrigation solution, aspiration is attempted again. This procedure can be performed multiple times.
• Following several rounds of irrigation and aspiration, the aspirated blood should be bright red, indicating adequate oxygenation.[26]
  • This finding is a promising sign as it indicates reoxygenation of the corporal tissues, which increases the vasoactive response to the phenylephrine injections.[8]

• Injections are repeated every 5 minutes until either 60 minutes has passed, 5 phenylephrine injections have been given, or a total of 1000 µg of phenylephrine has been administered.[1]
• If no progress has been made after repeated penile irrigations and aspiration alone, phenylephrine injections are performed in approximately 200 µg increments (usually 1 mL injections from a prepared syringe of phenylephrine solution diluted to 200 µg/mL).[1][27]
• Injections are repeated every 5 minutes until either 60 minutes has passed, 5 phenylephrine injections have been given, or a total of 1000 µg of phenylephrine has been administered.[1]
  • Vital signs should be checked before and periodically after the injection of phenylephrine, along with continual reassessment for symptoms of hypertension.
  • Once phenylephrine is administered, the patient should be connected to a cardiac monitor and have frequent blood pressure measurements (every 5-10 minutes is recommended).
  • There is some evidence that higher phenylephrine concentrations may produce better results, but this also increases the risk of side effects such as hypertension.[28]

• After detumescence, patients should be monitored for the recurrence of priapism and for any adverse effects related to phenylephrine injections.
• Direct pressure should be applied to the butterfly needle insertion sites for 1 minute after removal.
• If repeated irrigation, aspiration, and intracavernosal injections are unsuccessful, surgical intervention with a cavernosa to spongiosum shunt, which is typically performed in the operating room, should be considered.[1][8][19][29]
• Please see StatPearls' companion resource, "Priapism," for further information.[1]

Post-Procedure: Ischemic Priapism

Gauze and a self-adherent elastic wrap can be placed on the puncture site to help prevent any penile hematomas. If possible, the underlying cause of the priapism should be eliminated. Patients should be instructed to seek immediate medical attention if the priapism returns.

Proximal shunts and penoscrotal corporal decompression should be considered when distal shunting procedures are unsuccessful.[30] Early penile prosthesis implantation is another option after the failure of distal shunting procedures.[31]

The intermittent use of vacuum erection devices to passively engorge the corpora and stretch the penile tissues is encouraged after shunting.[30][32] This approach helps reduce the risk of penile fibrosis, particularly when a late penile prosthesis may be needed due to medically unresponsive erectile dysfunction before the priapism.[30]

Other Recommendations: Ischemic Priapism

The American Urological Association Guideline states that conservative management for ischemic priapism, including exercise, ejaculation, ice packs, cold baths, and cold water enemas, lacks evidence of benefits and is unlikely to be successful.[33][34]

In the setting of sickle cell disease, exchange transfusion may be necessary for definitive treatment.[3][35][36] Please see StatPearls' companion resource, "Stuttering Priapism (Recurrent or Intermittent Priapism)," for further information.[3][27][34][37]

Nonischemic Priapism

This type of priapism is generally non-emergent, painless, and does not require immediate corrective therapy. Conservative measures can generally be used, including ice and perineal pressure, or in some cases, it may spontaneously resolve. Surgical treatment should be managed and coordinated by urology and may consist of selective or superselective arterial embolization by interventional radiology or surgical ligation.[1][6][33][38][39][40][41]

Complications

Procedure

Pain is commonly associated with this procedure, even when an adequate penile block is performed. Phenylephrine is an alpha-adrenergic agonist that can cause headaches, dizziness, blurry vision, hypertension, bradycardia, tachycardia, and irregular cardiac rhythms. Because of these risks, the patient's vitals need to be closely monitored, and the dosage of phenylephrine should be limited to 1000 µg in 1 hour. Recurrence is possible and is an indication that the patient may require additional treatment, possibly including a more invasive procedure.

Post-procedure

• Penile irrigation, aspiration, and injection therapy should be treated as a sterile surgical procedure.[1]
• Prophylactic antibiotics are not routinely recommended after such procedures.
• Familiarity with penile anatomy and proper procedure will prevent inadvertent needle placement in the urethral or damage to the neurovascular bundle.
• A penile hematoma can form following the puncture of the tunica albuginea, but this can be reduced with an appropriate pressure dressing. Direct manual compression over the puncture site for 1 minute is generally sufficient to minimize this problem.
• Endothelial cell damage, fibrosis, and scarring may occur and are directly related to the duration of the priapism. Such changes start at about 14 hours, become significant after 36 hours, and are almost certain after 72 hours.[15]
• The duration of the priapism is directly correlated with future erectile dysfunction due to ischemic and vascular damage, as well as associated fibrosis. Loss of penile length can also occur due to fibrosis if an early (within 3 weeks) penile prosthesis is not placed in patients with refractory or long-duration ischemic priapism.[42][43][44][45]
• Recurrent episodes of priapism (stuttering priapism) are possible but can be suppressed with low-dose, continuous PDE5 inhibitors.[3]
• Patients with recurrent priapism should be screened for sickle cell disease.[3]
• Glans necrosis is a devastating but very rare complication of ischemic priapism. Distal shunt procedures can minimize this risk.[1][46]

Clinical Significance

Penile injection and aspiration is a vital procedure in the preservation of penile erectile tissue when patients experience ischemic priapism.[1][18] These techniques can be performed by clinicians who feel comfortable with minimally invasive bedside procedures.

Aspiration alone is successful in only about one-third of patients, whereas adding irrigation increases the success rate to about two-thirds.[1][47] The overall success rate is reported at about 86% with aspiration, irrigation, and vasoactive phenylephrine intracorporal injections if performed within 24 to 36 hours of the onset of the priapism.[28]

The duration of the ischemic priapism before treatment is the most reliable prognostic indicator.[48]

Approach to Priapism When Irrigation, Aspiration, and Phenylephrine Injections Fail

From 80% to 94% of ischemic priapism cases that are resistant to irrigation and aspiration with phenylephrine intracorporal injections will respond positively to distal corpora-spongiosum shunts with or without tunneling, with low complication rates and the maintenance of normal erectile function in up to 62%.[1][49][50][51][52][53] The longer the duration of the priapism, the lower the success rate and the poorer the outcome.

In general, ischemic priapism greater than 24 hours results in erectile dysfunction in 90% of affected men.[1][8] If the patient has exceeded the 72-hour mark before treatment commences, the chances of normal future erectile function are virtually zero, and he can be treated conservatively, controlling his pain.[1][20][49] In such long-duration priapism cases, consideration should be given to the insertion of a penile prosthesis, anticipating that erectile dysfunction inevitably follows, together with penile shortening and severe corporal fibrosis.[1][30][31][34][42][54][55][56][57]

Placement of a penile prosthesis is recommended within approximately 3 weeks of priapism onset, but no longer than a few months before corporal fibrosis occurs, making the surgery far more technically challenging.[1][31][42][43][44][57][58]

Proposed benefits include the lack of corporal fibrosis, less penile shortening, lower overall complication rates, easier prosthesis implantation, shorter operative times, higher patient satisfaction scores, and lower overall cost.[31][42][43][54][55][56][58][59][60][61][62][63][64] Overall, the best outcomes were found when a penile prosthesis was used for definitive therapy in patients with ischemic priapism >48 hours, and it is the recommended treatment for such patients according to the AUA and EAU Sexual and Reproductive Health Guidelines panel.[34][56][57]

The American Urological Association (AUA) Guidelines recommend immediate insertion of a penile prosthesis for patients who have failed all less aggressive measures, including conservative therapy, irrigation and aspiration, phenylephrine intracorporal injections, and shunt procedures, as well as for patients with priapism of more than 36 hours duration.[33][34][34][57] Immediate penile prosthesis insertion is the recommended first-line treatment for ischemic priapism with a duration of more than 72 hours.[34]

Enhancing Healthcare Team Outcomes

Prompt diagnosis of priapism allows for the early initiation of proper treatment. Effective management requires coordinated communication within an integrated interprofessional team to ensure prompt implementation of treatment plans. This approach minimizes delays in diagnosing and treating ischemic priapism, thereby improving clinical outcomes and reducing the risk of subsequent erectile dysfunction.

Preserving erectile function reduces the need for additional interventions, lowers overall healthcare costs, and promotes higher patient satisfaction. Knowing when not to perform an intervention decreases unnecessary pain, costs, and risks to the patient.

An interprofessional team that provides a holistic and integrated approach to priapism can help achieve the best possible outcomes. Treating priapism in a timely manner using injection and aspiration therapy can prevent the new development of erectile dysfunction. Therefore, with timely treatment, further intervention for erectile dysfunction can be avoided, improving patient satisfaction and decreasing the risk to patients.

Collaboration, shared decision-making, and communication are key elements for a good outcome. The interprofessional care provided to the patient should use an integrated care pathway combined with an evidence-based approach to planning and evaluation of all joint activities. The earlier signs and symptoms of a complication are identified, the better the prognosis and outcome of treatment.