Urology
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Question 27 of 180
A 21 year old man presents to ED with a sustained erection ongoing now for about 4 hours. He is in significant pain. He explains that he has taken a couple of sildenafil tablets as a practical joke. He has no significant past medical history and takes no regular medications. You administer a local anaesthetic block. What is your next immediate management step?
Answer:
- In the majority of patients presenting within 24 h, prompt intervention should be able to achieve penile detumescence.
- Arrange Doppler ultrasonography urgently, but do not let this delay aspirating blood from the penis which is both diagnostic and therapeutic.
- Following a local anaesthetic penile block, a large 19-gauge needle or butterfly is inserted into the corpus cavernosum, either through the lateral penile shaft or through the glans penis into the tip of the corpus cavernosum, followed by aspiration of blood from the corpus cavernosum.
- Following aspiration of blood from the corpus cavernosum, failure of detumescence should be followed by instillation of a sympathomimetic or a-adrenergic agonist. Phenylephrine is recommended and can be given in 200–250 µg aliquots. Injection is directly into the corpus cavernosum at the 3 or 9 o’clock position, therefore avoiding the urethra and dorsal neurovascular bundle. The injection can be repeated after 10 minutes, up to a total dose of 1000 µg, provided that there is no significant systemic hypertension.
Priapism
Urology
Last Updated: 19th September 2022
Priapism is defined as a prolonged penile erection (>4 h) which is maintained without sexual stimulation and persists despite ejaculation and orgasm. Priapism is a medical emergency requiring an accurate diagnosis and urgent medical intervention.
The two main subtypes of priapism are ischaemic priapism (also referred to as low-flow priapism), and non-ischaemic priapism (also referred to as high-flow priapism). A rarer subtype, referred to as stuttering or recurrent priapism, is defined by frequent prolonged and painful erections which are generally self-limiting and are common in patients with sickle cell disease (SCD).
Causes
- Ischaemic priapism
- Thromboembolic/hypercoagulable states
- Haemoglobinopathies (e.g. sickle cell disease, thalassaemia), thrombocytosis, assorted haematological dyscrasias, heparin-induced platelet aggregation
- Neoplastic disease
- Local primary (penile carcinoma, squamous cell carcinoma, prostatic adenocarcinoma) or metastatic neoplasia (metastases to the penis from, e.g. urothelial carcinoma of the urinary bladder, cancer of the prostate, rectosigmoid, kidney, or colon, and chronic myeloid leukaemia)
- Neurological disease
- As a consequence of 'spinal shock' in acute spinal cord injury, cauda equina syndrome, multiple sclerosis, spinal cord tumour with compression, or neurotoxins
- Infection
- Rarely, ischaemic priapism may be seen in pelvic infection
- Vasoactive agents, medications, and legal/illegal drugs
- These include erectile dysfunction pharmacotherapies (e.g. phosphodiesterase-5 [PDE5] inhibitors and intracavernous alprostadil), antihypertensives (e.g. hydralazine, prazosin), antipsychotics (e.g. chlorpromazine), and antidepressants (e.g., trazodone).
- In addition, alcohol and cocaine may predispose to ischaemic priapism.
- Thromboembolic/hypercoagulable states
- Non-ischaemic priapism
- This is much rarer than ischaemic priapism, and is predominantly caused by traumatic injuries. Mechanisms include straddle injury, coital trauma, kicks to the penis or perineum, pelvic fractures, birth canal trauma to the newborn male, and vascular erosions complicating metastatic cancer infiltration of the corpora cavernosa.
Pathophysiology
- Ischaemic priapism
- Ischaemic priapism is thought to be the result of an imbalance in the vasoconstrictive and vasorelaxatory mechanisms governing penile erection. Studies suggest that both vascular stasis within the penis and reduced venous outflow are the primary pathophysiological features in ischaemic priapism. Deoxygenated blood in the penis becomes trapped, creating venous congestion. The tissue ischaemia and increased pressure generated within the corporal bodies lead to the pain and penile rigidity clinically seen with ischaemic priapism.
- Non-ischaemic priapism
- Non-ischaemic priapism is much rarer and has a different pathophysiological basis. It is the result of unregulated cavernous arterial inflow. Most episodes are trauma-induced, whereby the cavernous artery or one of its tributaries within the corpora becomes lacerated, creating an arteriolar-sinusoidal fistula. The disruption of penile arterial circulation results in excessive arterial inflow to the penis. This produces unregulated pooling of blood in the sinusoidal spaces, with consequent erection. Cavernous blood gases do not show hypoxia, hypercarbia, or acidosis. Therefore, non-ischaemic priapism is not a medical emergency.
History and examination
History:
The duration of the priapism episode should be established and categorised into one of three time periods: (i) duration <48 h; (ii) duration 48–72 h; and (iii) duration >72 h.
Key points to establish from the clinical history include:
- Onset of the erection.
- Any underlying haematological disorders.
- Current medication.
- Illicit drug use.
- Symptoms to suggest an underlying pelvic malignancy.
- Previous episodes including stuttering priapism.
- Recent perineal or penile trauma.
- Any neurological symptoms.
Examination:
With regard to patient examination, the following points should be considered:
- It is important to differentiate between ischaemic priapism and non-ischaemic priapism. Ischaemic priapism presents as a painful rigid erection with a progressive increase in the pain as the duration of the priapism increases.
- Non-ischaemic priapism is painless or uncomfortable. There may be evidence of perineal or penile trauma.
- An abdominal examination and a digital rectal examination is required as there may be an underlying pelvic malignancy.
- A neurological examination should also be performed and documented.
| Ischaemic priapism | Non-ischaemic priapism |
|---|---|
|
|
Investigations
- Blood tests
- A full blood count and, in selected cases, a blood film should be performed to diagnose haematological disorders, and an autoimmune screen is also required.
- Cavernous blood gas analysis
- Blood aspirated from the penis should undergo blood gas analysis. A sample of the blood aspirated from the penis is sent for estimation of pO2/pH and glucose using a standard blood gas analyser. The presence of hypoxia, acidosis and glucopenia confirms a diagnosis of ischaemic priapism. The presence of normoxia correlated with the clinical history indicates that this is a non-ischaemic priapism; however, this should be confirmed with penile Doppler studies.
- Imaging
- When possible, arrange an urgent penile Doppler study. In ischaemic priapism, minimal or absent blood flow is seen in the cavernosal arteries, as well as within the corpora cavernosa; patients with non-ischaemic priapism have normal to high blood flow velocities in the cavernosal arteries with evidence of blood flow in the corpora cavernosa.
- Penile MRI can be used in order to assess the viability of the corpus cavernosum in refractory cases and aid in the decision to proceed with an early penile prosthesis.
- Abdominal and pelvic imaging using CT/MRI is performed in patients with a possible underlying pelvic or abdominal malignancy and in idiopathic cases. Idiopathic priapism also requires chest X-ray.
Management
- Ischaemic priapism
- Priapism Duration <48 h
- In the majority of patients presenting within 24 h, prompt intervention should be able to achieve penile detumescence; however, with presentations up to 48 h there is a decreased probability of achieving complete penile detumescence.
- Ensure that patients have adequate analgesia and broad-spectrum antibiotic cover prior to the procedure.
- Arrange Doppler ultrasonography urgently, but do not let this delay aspirating blood from the penis which is both diagnostic and therapeutic.
- Following a local anaesthetic penile block, a large 19-gauge needle or butterfly is inserted into the corpus cavernosum, either through the lateral penile shaft or through the glans penis into the tip of the corpus cavernosum, followed by aspiration of blood from the corpus cavernosum.
- Following aspiration of blood from the corpus cavernosum, failure of detumescence should be followed by instillation of a sympathomimetic or a-adrenergic agonist. Phenylephrine is recommended and can be given in 200–250 µg aliquots. Injection is directly into the corpus cavernosum at the 3 or 9 o’clock position, therefore avoiding the urethra and dorsal neurovascular bundle. The injection can be repeated after 10 minutes, up to a total dose of 1000 µg, provided that there is no significant systemic hypertension.
- If the priapism continues, then shunt surgery must be performed. Under local or general anaesthetic the simplest shunts to perform are distal shunts. In non-specialist centres either a Winter shunt or a T-shunt can be performed. If, despite these measures, the priapism persists, the patient should undergo a tunnelling procedure if the centre has the expertise or experience to perform this, or they should be referred to a specialist andrology unit for further management.
- Priapism Duration 48–72 h
- Corporal blood aspiration, followed by instillation of phenylephrine can still be attempted if there is doubt regarding the duration of priapism. Refractory priapism should then undergo shunt surgery. If imaging shows absent distal corpus cavernosum perfusion and the tunnelling procedure has failed, patients should be counselled regarding a penile prosthesis.
- Priapism Duration >72 h
- Patients presenting with a priapism after 72 h are unlikely to have viable smooth muscle within the corpus cavernosum. Corporal blood aspiration followed by the instillation of phenylephrine can still be undertaken if there is doubt regarding the duration of the priapism. The patient should then be referred urgently to a specialist andrology unit for further intervention or suitability for an early penile prosthesis insertion.
- Priapism Duration <48 h
- Non-ischaemic priapism
- If the underlying diagnosis is non-ischaemic priapism, based on the clinical history, penile Doppler studies and blood gas analysis, then the initial management can be conservative. If a fistula is demonstrated then duplex compression of the fistula can be performed. Failure of resolution of the priapism requires referral to a specialist unit offering superselective arteriography and embolisation with absorbable material.
- Stuttering priapism
- Stuttering priapism is a rare condition and the management is mainly based on small case series or anecdotal reports. In idiopathic cases, hormone manipulation using antiandrogens appears to be the most effective treatment to control the frequency of these episodes; however these should be avoided in prepubertal boys. Patients with SCD should be managed jointly with the haematology team. In patients with SCD etilefrine has been shown to be useful, but only available on a named patient basis.
Complications
- Penile ischaemia
- Penile fibrosis and deformity
- Erectile dysfunction
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
