Understanding Priapism: Causes, Symptoms, and Treatment

Priapism is a pathological condition representing complete or partial penile erection that continues for more than four hours and is beyond or unrelated to sexual interest or stimulation.

• Less than 4 hours—prolonged erection
• More than 4 hours—priapism

Historical Aspects

1. Priapism: Greek; God Priapus, who was worshipped as a god of fertility and protector of horticulture.
2. First literature is attributed to Tripe (1845).
3. Frank Hinman—a natural history of priapism (Hinman, 1914). And described “acute transitory attacks of priapism.”
4. Frank Hinman Jr. in 196: Venous stasis, increased blood viscosity, and ischemia were responsible for priapism.

Anatomical Physiology of Erection

• 2 corpus cavernosum
• 1 corpus spongiosum
• Buck's fascia: surrounding corpus cavernosum and spongiosum
• Tunica albuginea: surrounding corpus cavernosum
• Helicine arteries→ subtunical venous plexus→ Emissary vein→ joining circumflex vein→ enter into deep dorsal vein.

Erect: Emissary vein comprised.

• Cavernosal smooth-muscle relaxation causes increased arterial flow and engorgement and rigidity.
• Engorgement of the corpora cavernosa compresses the venous outflow tracts (i.e., subtunical venules), trapping blood within the corpora cavernosa.
• Nitric oxide is the major neurotransmitter secreted by the endothelium that lines the corpora cavernosa.

Also read: Peyronie's Disease and It’s Management

Phases of Penile Erection

1. Flaccid Phase
2. Latent Filling Phase
3. Tumescent Phase
4. Full Erection Phase
5. Rigid Erection Phase
6. Detumescence Phase

Mechanism of Erection

• Nitric oxide is the primary neurotransmitter.
• Regulation of smooth muscle relaxation and effect of PDE5 inhibitors.
• Nitric oxide produced by endothelium: L-arginine and O2 combination.
• Nitric oxide → cGMP (controls act of erection) → PKG (CGMP specific protein kinase) → protein-p → lower Ca2+ → relaxation of vascular smooth muscle → increase the blood flow into the corpus cavernosa → ERECTION.

In cases of erectile dysfunction, PDE5 inhibitors are given to prolong the action of cGMP.

Types of Priapism

• Ischemic priapism (low flow): persistent erection marked by rigidity of the corpora cavernosa with little or no cavernous arterial inflow.
• Nonischemic priapism (arterial high flow): persistent erection caused by unregulated cavernous arterial inflow; corpora are tumescent but not rigid and not painful.
• Stuttering priapism: recurrent prolonged.

Etiology of Ischemic Priapism

• Idiopathic
• Haematological dyscrasias (sickle cell disease, thalassemia, leukaemia; multiple myeloma, Hb Olmsted variant, fat emboli during hyperalimentation, haemodialysis, glucose-6-phosphate dehydrogenase deficiency, factor V Leiden Mutation)
• Infections (toxin-mediated) (i.e. scorpion sting, spider bite, rabies, malaria)
• Metabolic disorders (i.e. amyloidosis, fabry's disease, gout)
• Neurogenic disorders (i.e., syphilis, spinal cord injury, cauda equina syndrome, autonomic neuropathy, lumbar disc herniation, spinal stenosis, cerebrovascular accident, brain tumor, spinal anesthesia)
• Neoplasms (metastatic or regional infiltration) (i.e., prostate, urethra, testis, bladder, rectal, lung, kidney)
• Medications
  • Vasoactive erectile agents (i.e., papaverine, phentolamine, prostaglandin E1/alprostadil, combination of intracavernous therapies).
  • Alpha-adrenergic receptor antagonists (i.e., prazosin, terazosin, doxazosin, tamsulosin)
  • Antianxiety agents (hydroxyzine)
  • Anticoagulants (heparin, warfarin)
  • Antidepressants and antipsychotics (i.e., trazodone, bupropion, fluoxetine, sertraline, lithium, clozapine, risperidone, olanzapine, chlorpromazine, thioridazine, phenothiazines)
  • Antihypertensives (i.e., hydralazine, guanethidine, propranolol)
  • Hormones (i.e., gonadotropin-releasing hormone, testosterone)
  • Recreational drugs (i.e., alcohol, marijuana, cocaine [intranasal and topical] crack, cocaine)

Ischemic Priapism

• 35% after intra cavernous injections of papaverine-based combinations
• Rare (< 1%) after prostaglandin E1 monotherapy
• Priapism is rarely seen with PDE5Is (only sporadic cases reports)
• Ischemic priapism (veno-occlusive, low flow): persistent erection with little or no cavernous arterial inflow.
• Progressive hypoxia, hypercarbia, and acidosis
• Penile pain d/t Ischemia after 6-8 hrs
• Analogous to muscle compartment syndrome

Etiopathogenesis of Ischemic Priapism

Most common, most serious and most dangerous (acute ischemia of corpora cavernosa)
Seriousness is directly related to severity of the obstruction and the duration of the blockage
Cavernous hypoxia and acidosis begin after 4 hours and increase to peak levels in 24 hours
Po2 and pH of the trapped blood decrease to the levels of anoxia and acidosis

Hypoxia and acidosis lead to loss of contractility of the cavernous smooth muscle, impairing the venous stasis
Changes: edema, anoxia, and necrosis—leading to irreversible fibrosis
TGF beta: progression of the corporal, smooth-muscle fibrosis

Also read: Prostatic Carcinoma: Screening, and Treatment Options

SCD Priapism

Stagnation of the blood within Sinusoids of corpora cavernosa during physiologic erection, secondary to obstruction of Venous outflow by sickled erythrocytes

Pathology

Tissue necrosis and progressive fibrosis are the end-stage manifestations of ischemic priapis

• After 12 hrs: trabecular interstitial edema develops
• After 24 hrs: sinusoidal endothelium is denuded and thrombocytes adhere to the exposed basement membrane
• After 48 hrs: thrombi form in the sinusoidal spaces and smooth muscle cells, undergo necrosis or become transformed to fibroblast-like cells
• Irreversible effects: hypoxia, acidosis, and glucopenia
• Reperfusion injury: cavernosal tissue sustains damage from oxidative stress

Evaluation and Diagnosis of Priapism

History

• Duration of erection
• Presence and degree of pain
• Previous episodes of priapism and method of treatment
• Baseline erectile function
• Use of any erectogenic therapies
• Medications and recreational drugs
• Sickle cell, hemoglobinopathies, hypercoagulable states
• Trauma to the pelvis, perineum, or penis
• History of malignancy (prostate cancer)
• Penile prosthesis: may mimic priapism
• Recent urologic surgery

Physical Examination

• Penile color, rigidity, and sensation
• Penile discharge, lesions
• Evidence of local trauma
• Presence of prosthetic devices
• Regional lymphadenopathy (metastatic disease)
• Rectal tone: High spinal cord lesions or stenosis
• Abdominal Examination
• Testicles, perineum, rectum, and prostate—primary
• Malignant infiltration of the penis can cause indurated nodules within corporal tissue
• Aspiration of cavernosal blood—diagnostic and therapeutic

Also read: Undescended Testis: Causes, Treatment Options, and Risks

Investigations

Blood gas analysis and color duplex ultrasonography are currently the most reliable diagnostic methods of distinguishing ischemic from non-ischemic priapism
Blood aspirated from the corpus cavernosum—in pts with ischemic priapism is hypoxic and therefore dark red, while in pts with non-ischemic priapism is normally oxygenated and therefore bright red.

• Blood gas analysis: Aspiration of penile blood and analysis
• Color Doppler ultrasonography:
  • Lithotomy or frog leg position
  • Inspect the perineum and then the entire penile shaft
  • Colour Duplex ultrasound can be used as an alternative or adjunct to blood gas analysis
  • Scanning of the penis should be performed before aspiration in ischaemic priapism
  • Examination of the penile shaft and perineum is recommended. In ischaemic priapism there will be an absence of blood flow in the cavernous arteries
  • The return of the cavernous artery waveform will result in successful detumescence
  • Ischemic priapism: no blood flow in the cavernosal arteries
  • Nonischemic priapism: normal to high blood flow velocities in the cavernosal arteries
  • Screening test for anatomical abnormalities such as cavernous artery fistula or pseudoaneurysm
• Penile arteriography: Identify the presence and site of cavernous artery fistula. Reserved for the management of high flow priapism when embolization is planned.

Role of MRI

• Imaging of a well-established arteriolar sinusoidal fistula to demonstrate presence and extent of tissue thrombus and corporal smooth muscle infarction/fibrosis
• Imaging of corporal metastasis/primary lesion

Laboratory Testing

• Hemoglobin
• WBC with differential count
• Platelet count
• Coagulation profile
• Reticulocyte count and hemoglobin electrophoresis should be considered in all unless there is another obvious cause of priapism
• Emergency setting: screening for SCD should be performed by either the Sickledex test or examination of a peripheral smear

Sickledex Test

• Principle: Deoxygenated Hb-S is insoluble in the presence of a concentrated phosphate buffer solution and forms a turbid suspension
• Positive: cloudy turbid suspension, through which black lines are not visible
• Negative: transparent suspension, through which black lines are clearly visible

Also read: Injuries Of Testis And Testicular Torsion

Management of Ischemic Priapism

Therapeutic Goals

1. Alleviate pain and fear
2. Abort the erection
3. Maintain detumescence
4. Prevent long-term complications, particularly ED (Fibrosis set in 36-48 hours starts by 24 hours (TGF beta))

Stepwise Management

• Recommendation: Aspiration should be the initial treatment of ischemic priapism.
• Aspiration alone may relieve priapism in 36% of patients.
• Can be repeated until fresh, bright red blood is obtained.
• A marked decrease in the intracavernous pressure relieves pain and removes anoxic, acidotic, and hypercarbic blood.
• Initial corporaaspirations in ischemic priapism show dark, deoxygenated blood; subsequent aspirations will show brighter blood.

Initial Conservative Measures

• Local anesthesia of the penis
• Insert wide-bore butterfly (16-18G) through the glans into the corpora cavernosa
• Aspiration of cavernosal blood until bright red arterial blood is obtained.

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Cavernosal irrigation

• Irrigate with 0.90% w/v saline solution

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Intracavernosal Therapy

• Inject intracavernosal adrenoceptor agonist
• Current first-line therapy is phenylephrine, with aliquots of 200 μg being injected every 3-5 min. until detumescence is achieved (maximum dose of phenylephrine is 1 mg within 1 hour)

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Surgical Therapy

• Surgical shunting
• Consider primary penile implantation if priapism has been present for more than 36 hours. A large-bore, 1–21-gauge needle should be inserted at the peno-scrotal junction at 2 o'clock or 10 o'clock positions. The surgeon should compress the penile shaft just below the 19-gauge needle, aspirating the shaft until it is soft.

Also read: Anatomy Of The Testis And Its Types

Treatment of SCD-Induced Ischemic Priapism

• Analgesics
• Hydration
• Oxygen
• Bicarbonate
• Blood transfusion
• Systemic resolution alone is not effective in the management of SCD priapism.
• Best resolution rates are achieved with therapy directed at the penis.

Medical Treatment of Ischemia

• Phenylephrine: Intravavernous injection of 200 μg every 3-5 min.
• Maximum dosage is 1 mg within 1 hour.
• The lower doses are recommended in children and patients with severe cardiovascular disease.
• Etilephrine: intravenous injection at a concentration of 2.5 mg in 1-2 mL normal saline.
• Methylene Blue: intracavernous injection of 50-100 mg, left for 5 min. It is then aspirated and the penis compressed for an additional 5 minutes.
• Adrenaline: Intracavernous injection of 2 mL of 1/100,000 adrenaline solution up to five times over a 20-minute period.
• Terbutaline: Oral administration of 5 mg for prolonged erections lasting more than 2.5 hours after intracavernous injection of vasoactive agents.

Surgical Treatment of Ischemic Priapism

• Surgical shunting should not be considered as first-line therapy
• Consider only after:
  1. Failed trial of intracavernous injection of sympathomimetics
  2. Such an attempt has resulted in significant cardiovascular side effects.

Treatment of Non-Ischemic Priapism

• Not painful
• Natural history is resolution
• Rarely non-ischemic Priapism can occur after resolution of ischemic priapism
• 62% resolve it conservative management (ice compression)
• Corporal aspiration has only a diagnostic role
• No comparative outcome studies of intervention vs conservative management
• Aspiration with or without injection of sympathomimetic agents is not recommended
• Initial management: observation
• Immediate invasive interventions embolization or surgery: at the request of the patient

Also read: High-Yield NEET SS Surgery Urology Questions

Treatment of Stuttering Priapism

• Oral Terbutaline: beta 2-agonist with minor beta-1 effects and some alpha agonist activity
• Dose of 5 mg for prolonged erections > 2.5 hours after intracavernous injection of vasoactive agents
• Main use: prevention of recurrent episodes of prolonged erections.
• Goal: prevention of future episodes
• Oral alpha-adrenergic medications (e.g., etilefrine 0.5 mg/kg / day at bedtime)
• Hormonal therapy: GnRH agonists, antiandrogens

Contraindications

a. Children who have not completed their growth and sexual maturation;
b. Those trying to conceive

• Baclofen: Oral 40 mg at bedtime
  • Inhibits penile erection and ejaculation through GABA receptor activity
• PDE5 Inhibitors: Selective vasodilation of the corporal blood vessels prevents sickling of red cells in the corporal bodies.
  • Sildenafil: 25 mg OD; Tadalafil: 5 or 10 mg thrice weekly
• Intracavernosal self-injection of phenylephrine should be considered in patients who either fail or reject systemic treatment of stuttering priapism.

Hope you found this blog helpful for your NEET SS Surgery urology preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.