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Ivan Koay, MBChB, FRNZCUC, MD
A 40-year-old man walks into the Urgent Care center complaining of a painful penis, having woken up a few hours earlier with the pain. He initially woke up with a painful erection. The pain continued but the erection has subsided a little. He denies any trauma, there was no sexual activity in the preceding hours or previous evening. He had taken some Tylenol a couple of hours prior to presenting to the UCC. He had passed urine a couple of times since the pain started; he denied noticing any blood in the urine during those times. There was no abdominal pain and no fever. There was no other past medical history of note.
Clinical examination noted no fever, pulse of 78 beats per minute and regular, oxygen saturations of 98% on air. He had a normal cardiovascular examination, abdominal examination was unremarkable, genitalia examination showed a semi-tumescent penis that was slightly painful to palpate, non-tender and normal lying testes. Urine dip revealed 1+ blood and 1+ leukocytes, negative nitrates, negative glucose, and ketones.
What are the plausible differentials:
A. Lower urinary tract infection
B. Sexual transmitted infection
C. Cellulitis
D. Priapism
E. More information needed
On further direct questioning, he denied any previous history of STIs and he has one female partner with whom he has been with for the last 10 years and never been unfaithful. He also denies using any other recreational substances. He admits to having a similar episode about a year ago which resolved after going for a walk.
Answer D: Priapism
Priapism is defined as a prolonged and persistent penile erection, unassociated with sexual interest or stimulation, lasting longer than 4 hours. It is divided into three main categories based on the aetiology and pathophysiology of the condition: ischemic, non-ischemic and stuttering priapism.
Ischemic priapism (the most common with 95% of presentations), also termed veno-occlusive or low flow priapism, is a persistent erection marked by rigidity of the corpora cavernosa and little or no cavernous arterial inflow. It consists of an imbalance in vaso-regulatory mechanisms, predisposing the penis to an ischemic environment. The tissue ischemia and increased pressure generated within the corporal bodies lead to pain and rigidity, classically seen with ischemic priapism. This constitutes a true urological emergency.
Non-ischemic priapism, also termed arterial or high-flow priapism, is a persistent erection caused by unregulated cavernous arterial inflow. This generally occurs due to trauma, creating a disruption in the cavernous arterial anatomy, resulting in an arteriolar-sinusoidal fistula. The cavernous environment does not become ischemic secondary to the continuous influx of arterial blood. The corpora are tumescent but not rigid, and patients typically do not complain of pain with erection, therefore non-ischemic priapism is not an emergency and does not require immediate intervention.
Stuttering priapism, also termed intermittent or recurrent priapism, is characterized by recurrent episodes of ischemic priapism and typically last <4h prior to remission. These episodes may increase in frequency and duration, however, compromising the patient’s quality of life and potentially developing into major episodes of ischemic priapism. Both stuttering and ischemic priapism result in the same consequence, namely, ischemic damage to the corporal tissue. Therefore, all episodes of recurrent priapism that progress to prolonged, painful erections should be treated promptly, according to the guidelines set for ischemic priapism.
Diagnosis
Conditions predisposing to ischaemic priapism include sickle cell disease (SCD), assorted haematological dyscrasias, parenteral hyperalimentation, haemodialysis, heparin-induced platelet aggregation, and local primary (penile carcinoma/squamous cell carcinoma, prostatic adenocarcinoma) or metastatic neoplasia (metastases to the penis from prostate, rectosigmoid colon, kidney, urothelial carcinoma of the urinary bladder, chronic myeloid leukaemia). Medications implicated include alpha-adrenergic receptor antagonists (prazosin, terazosin, doxazosin, tamsulosin), anti-anxiety agents (hydroxyzine), anticoagulants (heparin, warfarin), antidepressants and antipsychotics (trazodone, bupropion, fluoxetine, sertraline, lithium, clozapine, risperidone, olanzapine, chlorpromazine, thioridazine), and antihypertensives (hydralazine, guanethidine, propranolol). Second-generation antipsychotics (33.8%), other medications (11.3%), and alpha-adrenergic antagonists (8.8%) account for most reported cases of drug-induced priapism. Alcohol and cocaine may predispose to ischaemic priapism.
Management must begin with a detailed history and physical examination. Diagnosis should focus on identifying any contributory/predisposing conditions, listed above. The duration of priapism, any clinical treatments used, previous priapism episodes, presence of pain, and erectile function status prior to the priapism episode should be noted. In patients with known SCD, it is particularly important to determine the presence of any other systemic symptomatology associated with SCD, such as a sickle crisis. A physical examination involving inspection and palpation of the penis, to assess for the extent of tumescence or rigidity, degree of corporal body involvement, and presence and severity of tenderness, is essential. Abdominal, perineal, and rectal examinations may reveal signs of trauma, pelvic infection, or malignancy. A full neurologic exam may be indicated when a spinal cord injury or lesion is suspected.
Within the UC centers, there is limited other modalities for imaging or laboratory testing to be performed. Patients that present to the UC and have been diagnosed with priapism require referral to the local urological service or emergency department for further work-up and assessment. In secondary care centers, where laboratory and imaging facilities are available, certain tests can be considered. However, these investigations should not delay the referral process but can be used as adjuncts for the referral process.
Laboratory Tests
A cavernous blood gas analysis will provide direct visualization and evaluation of penile blood, serving to provide immediate distinction between the different variants of priapism. In patients with ischemic priapism, the aspirated blood is hypoxic and dark, and typical blood gas values show a partial pressure of oxygen (pO2) of less than 30 mmHg, partial pressure of carbon dioxide (pCO2) of greater than 60 mmHg and a pH of less than 7.25. Conversely, in non-ischemic priapism, the blood is oxygenated and bright red with cavernous blood gas values of a pO2 greater than 90 mmHg, pCO2 less than 40 mmHg, and pH 7.40, consistent with normal arterial blood at room air. A complete blood count, white blood cell differential, and platelet count which may reveal the presence of acute infections or hematologic abnormalities. Reticulocyte counts and hemoglobin electrophoresis may signify the presence of SCD/trait or other hemoglobinopathies. These tests are recommended in all men unless the etiology of priapism is evident.
Radiological Imaging
Penile imaging may assist in the diagnosis of otherwise equivocal priapism cases and may be used in follow up to verify treatment success. Color duplex ultrasonography (CDU) of the perineum and penis can evaluate intracorporeal arterial blood flow in real time. This serves in conjunction with penile blood gas sampling to further differentiate ischemic from non-ischemic priapism. In ischemic priapism, minimal or absent blood flow is seen in the cavernosal arteries within the corpora cavernosa. Patients with non-ischemic priapism, however, will show characteristic normal to high blood flow velocities in the cavernosal arteries.
Treatment of ischemic priapism
Medical management
The most common complication of priapism is erectile dysfunction, which can occur in as many as 59% of cases. However, recovery of erectile function may be seen in up to 44% of patients who experience priapism for 24–36 h, therefore, “time is erectile tissue,” and timely treatment is crucial. First-line therapy for patients with episodes of acute ischemic priapism is aspiration of blood with irrigation of the corpora cavernosa, in combination with intra-cavernous α-agonist injection therapy (Fig 1,2,3). For most Urgent Care practitioners, this should only be done after discussion with the local urological service and only if there are significant delays in getting the patient definitive treatment by a urologist. The technique of penile blood aspiration involves using a transglanular intracorporal angiocatheter insertion or a proximal penile shaft needle access. For proximal penile shaft access, a 16- or 18-gauge angiocatheter is placed percutaneously into the lateral aspect of the penile shaft entering the corpus cavernosum. With a syringe attached, aspiration and evacuation of blood from the corpora cavernosa is performed with irrigation of normal saline or in combination with intra-cavernous injection of an α-adrenergic sympathomimetic agent.
Other treatment modalities include e hormonal therapies, which include gonadotropin-releasing agonists, androgen receptor antagonists, and 5α-reductase inhibitors, as well as other agents including digoxin, gabapentin, baclofen, terbutaline, and even phosphodiesterase 5 (PDE5) inhibitors.
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