Physicians should first think of the most probable etiologies of penile pain, such as sexually transmitted diseases or trauma. It is important, however, to then consider a broad range of differential diagnoses in each patient with genital pain.
LOCALIZED AND REFERRED PAIN
Independent penile pain is a rare complaint1 and may be secondary to a local disease or a result of referred pain. The inferior hypogastric plexus (T10-L1 (sympathetic) and S2-S6 (parasympathetic) nerves) is thought to be the neural integrative system in the pelvis that innervates the urinary bladder, proximal and distal urethra, rectum, and reproductive and genital structures.2 The neural supply of the penis is derived from the cavernosal and pudendal nerves (S2-S4).3 When the sensory nerves that innervate organs of similar embryonic origin are stimulated by a pathologic process,4 pain can be mislocalized to any area innervated by the spinal segment that also innervates the damaged viscera.5
PRIMARY AND SECONDARY CAUSES
The radiation of pain plays an integral part in determining urologic from non-urologic processes. Primary pathologic processes within the penis that can result in pain include urethritis, urethral foreign bodies, priapism, Peyronie's disease, trauma, paraphimosis, and external dermatologic conditions and/or insect bites (for example ant and spider bites). Primary processes involving areas adjacent to the organ that result in penile pain include prostatitis and scrotal disorders (such as testicular torsion, epididymitis, and orchitis). Pain experienced in a flaccid penis typically is the result of inflammation caused by sexually transmitted diseases or balanoposthitis, whereas pain in an erect penis is usually due to priapism or Peyronie's disease. Paraphimosis and balanitis should be considered in the differential diagnosis of penile pain in men who are uncircumcised.
Penile pain is associated with testicular torsion, blunt/straddle injury (penile trauma or penile fracture), penetrating injury, and the relatively under-diagnosed conditions of male genital pain syndrome,5 reflex sympathetic dystrophy,6 and painful male urethral syndrome.7 Patients with direct inguinal hernia,8 pudendal neuralgia,9,10 and pain disorder associated with psychological factors11,12 may also experience penile pain.
Testicular torsion
Testicular torsion is a urologic emergency that can cause penile pain. Torsion should be considered first in the differential diagnosis of adolescents with groin pain.
Trauma
Penile fracture is an unusual urologic emergency characterized by traumatic rupture of the tunica albuginea (one of the strongest fascial layers of the body) and of one or both corpus cavernosa affecting the rigid penis (figure). The incidence of penile fractures is unknown because such trauma is not always reported. Patients typically report striking their erect penis on an object, followed by the sudden onset of pain in the shaft of the penis and subsequent rapid detumescence. A cracking or popping sound may be heard at the moment of injury.
Figure 1.
Cross section of the penile shaft. The corpus cavernosa consists of masses of cavernous erectile tissue enclosed in a dense fibrous capsule, the tunic albuginea
Physical examination reveals swelling and ecchymosis of the penile shaft at the area around the flaccid corpora. Hematoma formation usually causes deviation of the penis to the opposite side of the injury. Blood at the urethral meatus or gross hematuria is indicative of urethral injury. Treatment of penile fracture involves surgical intervention (evacuation of the hematoma and repair of the tunica albuginea) or the use of nonsteroidal medications and compression dressings.
A straddle injury is a relatively common cause of penile pain in adolescents. Trauma of this type may also result in urethral injury.
When blood is found at the urethral meatus following penile fracture or straddle injury, retrograde urethrography is used to evaluate the extent of injury and to ensure safe placement of a Foley catheter if catheterization is required.
Acknowledgments
I thank Martin Anderson for this thorough review of the manuscript and for his guidance throughout my fellowship.
Competing interests: None declared
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