From the Outside to Inside

• Skin
• Dartos Fascia
• Bucks Fascia
• Tunica Albuginea
• Corpora Cavernosa
• Corpus Spongiosum
• Urethra

Image: Grays 1918

Penis has

• 3 Erectile tissues
• Corpora Cavernosa x 2
• Corpus Spongiosum x 1


Image: Moore

• 3 Muscles
• Bulbospongiosus
• Ischiocavernosis x 2


Image: Grays 1918

• 2 Ligaments
• Suspensory ligament
• Fundiform ligament


Image: Bourgey 1840



Image: Testut 1905

• 3 principle Arteries (paired)
• Dorsal Penile Artery
• Deep Penile Artery (or Cavernous Artery)
• Urethral Artery (or Bulbourethral Artery)


Image: Grays 1918



Image: Grays 1918

• 3 main veins
• Superficial Dorsal vein
• Deep Dorsal vein
• Bulbourethral vein


Image: Grays 1918



Image: Grays 1918



Image: Testut 1905

• 2 Nerves
• Dorsal penile nerve (Somatic supply from Pudendal Nerve)
• Cavernous Nerve (Autonomic supply)


Image: Grays 1918

Image: Grays 1918

Image: Grays 1918

• Reflexogenic
• Direct touch or stimulation
• Psychogenic
• Indirect stimulation via visual, auditory or imaginary stimulus
• Nocturnal
• During sleep at night

• Parasympathetic Stimulation (S2-4) [P for parasympathetic, P for Point]
• Vasodilation leading to engorgement of the vessels and cavernous vascular sinusoids
• Relaxation of the smooth muscles
• Sympathetic Stimulation (T11-L2) [S for Sympathetic, S for Shoot]
• Ejaculation through contraction of the Vas, the seminal vesicle and closure of the bladder neck with rhythmic contraction of bulbospongiosus muscle
• Loss of parasympathetic supply and increase in sympathetic signals results in loss of vasodilation, smooth muscle contraction and detumescence
• Somatic Control via Pudendal Nerve
• Sensory fibres take sensory signals from the external genitalia and initiate erection
• Motor fibres supplying the bulbospongiosus and ischiocavernosus muscles cause contraction of these muscles

• Contraction of the bulbospongiosus and ischiocarvernousus muscles reduces the venous outflow resulting in engorgement of the erectile tissues
• Vasodilation and smooth muscle relaxation causes distension of the corpora, which compresses the tunica albuginea and closes off the emissary veins, thus maintaining erection
• Relaxation of the bulbospongiosus and ischiocavernosus muscles, loss of vasodilation (or vasoconstriction) and return of smooth muscle tone causes shrinkage of the connective tissue releasing compression on the subtunical venous plexus and emissary veins leading to removal of blood

Nitric Oxide mediated mechanism

Nitric oxide is released from Parasympathetic NANC (non-adrenergic non-cholinergic) nerves and from the endothelial cells upon parasympathetic stimulation. This results in a cascade of reactions. cGMP and cAMP are formed, Protein Kinase is activated, which blocks the Ca Channels. This decreases the intra-cellular calcium levels and causes smooth muscle relaxation and vasodilation.

• Painful erection
• It is considered analogous to a compartment syndrome of the Penis
• It is caused by veno-occlusion, leading to poor or no blood flow (i.e. low flow), which lead to ischemia, which can be observed on blood gas analysis on penile aspirate blood
• It is the most common type of priapism (>95%)
• It is considered a urological emergency and urgent decompression is recommended
• Conservative measures are not successful and therefore are not recommended in clinical setting
• First line management: Penile coporal Aspiration with or without irrigation
• 2nd line management: Intra-corporal Phenylephrine injection
• 3rd line management: Shunt procedure
• 4th line management: Shunt procedure with tunneling or snake manouvre
• If complete detuescence is not achieved after shunting or tunneling, consider repeat blood gas. If arterial blood is identified then no further acute intervention is required as that signifies resolution of ischemia
• Early Penile Implant insertion: Delayed presentation of prolonged priapism can be considered for early penile implant insertion. If penile implant insertion is being considered, emergency shunting should not be done (as that increase risk of extrusion of the penile implant)

• Either painless or uncomfortable (not acutely painful)
• History of penile or perineal trauma is typically present
• Generally it is caused by AV fistula created from a traumatic event
• As arterial blood is flowing, blood gas does not show ischemia and therefore it is not considered a urological emergency
• Penile doppler US (including the perineum) should be considered to assess for AV fistual
• An initial period of monitoring/ observation is recommended as conservative management
• If conservative management fails and the fistula does not close spontaneously, embolisation can be considered
• If embolisation fails, a second attempt can be considered

Stuttering priapism is a rare type of priapism characterized by recurrent episodes of priapism.

Often associated with SCD.

Treatment option:

• Antiandrogens
• Pseudoephedrine
• Etilefrine
• Penile Prosthesis

• Sickle Cell Disease
• Incidence with SCD (Nelson and Winter 1977)
• Most common cause in childhood priapism 63%
• Primary cause in 23% of adult cases
• SCD is predominantly associated with ischemic priapism
• Pelvic Malignancy (<2%)
• Haematological dyscrasias/ malignancy (<1%)
• e.g. SCD, thalasemia, leukaemia (CML)….
• Intracavernosal injection
• Higher risk in Papaverine-based injection (~5%)
• Low risk in prostaglandin E1 injections (<1%)
• Drug induced
• e.g. antipsychotics, anti-depressants, alpha blockers, anticoagulants….
• PDE5i (very rare and causation unclear, sporadic cases)
• Recreational Drugs
• e.g. Cocaine, marijuana….
• Neurological conditions
• e.g. Cauda Equina Syndrome, Spinal Cord injury ….

See EAU guidelines for a comprehensive list of etiologies.

• Penile/ Perineal Trauma

Key points in history as per the BAUS Consensus 2018

1. Onset of the erection. 2. Any underlying haematological disorders. 3. Current medication. 4. Illicit drug use. 5. Symptoms to suggest an underlying pelvic malignancy. 6. Previous episodes including stuttering priapism. 7. Recent perineal or penile trauma; 8. Any neurological symptoms.

Also important to ask regarding

• Presence and degree of pain
• Use of intra-cavernosal injections
• Baseline erectile function

BAUS Consensus considers Abdominal, Rectal, Penile and Neurological exams as mandatory.

• Abdominal exam and Digital Rectal Exam: to assess for Pelvic Malignancy
• Neurological exam

Blood tests

• FBC
• Coagulation profile
• Haematological screening
• Blood film/ Blood smear
• Haemoglobin electrophoresis (for SCD/ thalassemia)
• Urine Toxicology (for illicit drug use)
• Penile Blood Gas Analysis

Involve hematology in patient’s with SCD or if suspicion of any hematological disorder.

Imaging

• Penile US (can be used in diagnosis, but should not delay management and intervention to achieve detumescence)
• If considered it should be performed before aspiration (EAU)
• Abdominal and Pelvic Imaging (CT/MRI) to assess for underlying malignancy
• Penile MRI can assess viability of corpus cavernosum smooth muscle (EAU)
• Patients with viable smooth muscle generally preserve erectile function, whereas non-viable smooth muscle on MRI should be offered prosthesis if they which to regain sexual function

• To achieve penile detumescence to
• Prevent corporal smooth muscle fibrosis
• Preserve erectile function
• Relieve pain

Evidence supporting the use of conservative measures is limited. Following conservative measure have been described in the EAU guidelines,

• Exercise (walking up and down stairs)
• Ejaculation
• Ice packs (at penis and perineum)
• Cold baths
• Cold-water enemas

AUA guidelines suggest these measures are unlikely to be successful and therefore should not delay definitive management.

These options can be considered within the first 4 hours of persistent unwanted erection.

In line with the BAUS Consensus 2018

Pre-requisites

• Penile Block
• Antibiotics

What to insert

• A large bore needle/cannula or butterfly (18G Green)

AI generated image

Where to insert

Inserted into the corpus cavernosum, either through the lateral penile shaft or through the glans penis into the tip of the corpus cavernosum

Insertion on the shaft is at the lateral aspects (consider 3 or 9 o’clock) to avoid injury to the urethra and the dorsal neurovascular bundle

How much to aspirate

Aspiration is done until fresh red blood is obtained.

No specific volume of aspiration is mentioned in the guidelines.

Irrigation

Irrigation with 0.9% saline can be considered.

Irrigation can be done from the same puncture site or an additional separate puncture can be done on the contralateral side.

Data is limited to suggest if aspiration with irrigation is superior to aspiration alone.

What is Phenylephrine

Phenylephrine is an alpha-1 adrenergic agonist, therefore acts as a sympathomimetic amine and causes vasoconstriction and smooth muscle contraction. This encourages detumescence.

Prerequisite:

• Cardiovascular monitoring throughout the procedure and then every 15mins for 1 hours afterwards (EAU)
• Blood Pressure
• Pulse

Dose of single injection:

• 200-250ug

Repeition interval between doses:

• Every 5-10mins (EAU=5min, BAUS=10min)

Maximum dose:

1000ug (i.e. 1mg)

How to prepare:

See BAUS Consensus Statement 2018

Other sympathomimetic agents that are described in EAU guidelines include

• Etilefrine (described in Priapism associated with SCD)
• Ephedrine
• Epinephrine
• Norepinephrine
• Metaraminol
• Adrenaline

As phenylephrine offers the safest risk profile, it is considered the first line option for injectable therapy for priapism.

Side effects:

• headache, dizziness, hypertension, reflex bradycardia, tachycardia and palpitations, and sporadic subarachnoid hemorrhage

Contraindications:

• In patients with malignant or poorly controlled hypertension (risk of CVA)
• Alongside monoamine oxidase inhibitors (risk of hypertensive crisis)

All shunt procedure have a very high rates of achieving detumescence but low rates of preserving erectile function (especially in case of prolonged ischemic priapism/ late presentation).

Some studies report a reoperation rate of 50% and ED rate as high as 90% (Nixon 2003).

Essentially, the risk of needing shunting (due to failure of other management options) increases after 24hr of priapism and similarly the risk of loss of erectile function also sharply rises after 24hr of priapism. Hence, patient who require shunting are inherently part of the cohort who would be at a high risk of erectile dysfunction with or without the shunting procedure. (data from Nelson Bennett MSKCC 2008)

Shunting procedures in patients who fail other management options would help resolve pain, achieve detumescence and limit ischemia and resultant fibrosis and penile shortening. Thus in early presentation it can potentially preserve erectile function whereas in late presentations it can improve outcomes of penile prosthesis implantation.

Described by Morey in 2018 as a safer final resort measure instead of an immediate penile implant in cases of Refractory Ischemic Priapism (RIP) when all other measures fail.

It involves making a 3cm peno-scrotal incision to reach the proximal corpora cavernosa. A 2cm corporotomy is done, which delivers dark ischemic bloods. Then a paediatric sucker is inserted through the corporotomy to such out rest of the old blood until fresh red oxygenated blood is recieved. Iriigation is done with saline. Similar procedure can be repeated on the other side.

The original paper describes closure of all layers however some expert suggest leaving a drain behind instead to prevent early recurrence.

Original paper reported a case series of 6 patients with 100% success rate and no significant complications reported. They compared it with 8 other patients who underwent immediate malleable penile implant, which had a 37% rate of revision surgery mainly due to implant extrusion.

A follow-up multi-institutional US retrospective study in 2020 on PSD was published by Morey on 25 patients, with key findings as

• Unilateral PSD had a 20% rate of recurrence of priapism, which was successfully managed with bilateral PSD. Therefore authors recommend doing bilateral PSD as standard.
• Mean duration of priapism was 71hr (minimum was 24hr)
• No significant complications were reported
• 15 patients completed follow-up. Of those 9 (60%) reported spontaneous erections adequate for penetration while 6 (40%) reported ED. Patients with preservation of erectile function has a shorter mean duration of priapism (59hr vs 72hr)

Types of Penile Implants:

• Malleable Semi-rigid implant
• Cheaper
• 3-piece inflatable implant
• More expensive

Timing of Penile Implantation:

• Immediate Implant
• Immediate implantation has been advocated in literature for Refractory Ischemic Priapism (RIP) when all other measures have been unsuccessful
• Immediate implant is offered after appropriate counseling and after smooth muscle biopsy or Penile MRI scan to confirm smooth muscle necrosis
• A malleable semi-rigid penile prosthesis is considered the implant of choice in most cases of Immdediate Penile Prosthesis Implantation
• David Ralph in UCLH reported their long-term data in 2009
• 50 patients who underwent immediate penile prosthesis implantation
• 96% patient satisfaction rate reported
• 84% had resumed sexual intercourse on follow-up
• 6% rate of infection reported
• Peno-scrotal decompression is being presented as a safer alternative in this group of patients with early studies showing very promising results (Morey 2020)
• Early Implant
• BAUS Consensus statement 2018 recommends early implantation (as compared to immediate or delayed implantation)
• EAU suggest early implant to be within 3 weeks of priapism episode
• This duration allows resolution of edema and healing from any shunt procedure that might have been attempted
• This is the preferred timing as it prevents the excessive penile fibrosis that happens with delayed implantation
• Delayed Implant
• It is considered less optimal as delays lead to fibrosis setting in which results in penile shortening, a difficult and more challenging procedure and therefore a higher risk of complications.