A 34-year-old man comes to the office due to a persistent, painful erection for 12 hours without sexual stimulation. He has had no trauma to the perineal region. Over the past few months, the patient has also had fatigue. He has no prior medical conditions and takes no medications. Family history is significant for stroke in his father and hypothyroidism in his mother. The patient does not use tobacco, alcohol, or illicit drugs. Temperature is 36.8 C (98.2 F), blood pressure is 120/78 mm Hg, and pulse is 100/min. There is no lymphadenopathy. Cardiopulmonary examination is normal. The liver and spleen are palpable. The penis is erect, is tender, and has venous engorgement. The remainder of the examination shows no abnormalities. The patient is given appropriate treatment, with reduction of symptoms. Which of the following is the most appropriate diagnostic test to identify the cause of this patient's symptoms?
Priapism | |
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Priapism is a prolonged, painful erection in the absence of ongoing sexual stimulation. In an erection, parasympathetic activation induces dilation of the cavernous arteries, increasing blood flow into the corpora cavernosa; this compresses the emissary veins against the tunica albuginea, blocking the outflow of blood. Subsequent sympathetic stimulation normally constricts arterial inflow and induces cavernosal smooth muscle contraction, leading to detumescence. However, persistent inflow or obstructed outflow can lead to priapism.
Most cases of priapism are idiopathic. However, priapism can be seen in hematologic disorders that cause altered blood viscosity or local microthrombi, leading to decreased outflow through the emissary veins. Common disorders include sickle cell disease, hematologic malignancies (eg, chronic myelogenous leukemia [CML]), thalassemia, and multiple myeloma. Priapism can also be caused by conditions (eg, spinal cord injury) or medications/drugs (eg, sildenafil, trazodone, cocaine) that cause abnormal autonomic or vascular tone.
This patient has priapism associated with fatigue and hepatosplenomegaly, suggesting a possible hematologic malignancy, such as CML, which usually presents in older adults although a minority of cases present in children and young adults. Appropriate laboratory studies are indicated, including a complete blood count (eg, leukocytosis with median count 100,000/mm3 in CML).
(Choice A) This patient has no cardiopulmonary signs or symptoms to indicate a chest x-ray. Chest imaging has low utility in identifying the cause of priapism.
(Choice C) Treatment of priapism with intracorporal phenylephrine can cause hypertension and reflex bradycardia; some experts advise electrocardiographic monitoring during treatment for patients with comorbid heart disease, but electrocardiography is not needed for routine evaluation.
(Choice D) Infectious mononucleosis can cause hepatosplenomegaly but not altered blood viscosity or priapism. Also, this patient has no other features of mononucleosis (eg, pharyngitis, lymphadenopathy).
(Choice E) Spinal cord disorders (eg, traumatic injury, spinal metastasis) can cause priapism due to disruption of autonomic innervation. However, this rarely occurs as an isolated finding; most patients have additional neurologic abnormalities (eg, urine retention, spinal shock).
(Choice F) Iron studies (eg, serum ferritin level) are indicated in the evaluation of hereditary hemochromatosis. This condition can cause central (secondary) hypogonadism, leading to erectile dysfunction but not priapism.
Educational objective:
Most cases of priapism are idiopathic. However, it can be seen in hematologic disorders that cause altered blood viscosity or local microthrombi, leading to decreased outflow through the emissary veins. Common disorders include sickle cell disease, hematologic malignancies (eg, chronic myelogenous leukemia), thalassemia, and multiple myeloma.