Rupture of the tunica cavernosa

• penile fracture is a relatively uncommon urological emergency. Unfortunately it is often misdiagnosed and may therefore be mistreated
• mechanism of injury:
  • the erect penis is relatively more prone to injury - the penile erection is maintained by two fibro-elastic tubes (tunica cavernosa) which are filled with blood (at a pressure of 100-200mm Hg)
  • if there is a sudden shearing force is applied to the erect penis or the erect penis is suddenly bent then there may a consequent rupture of the tunica cavernosa (as the intracavernosal pressure momentarily rises to supramaximal levels)
  • in most cases of penile fracture the cavernous bodies are only affected. However, urethral injury may also develop in 1% to 48% of the cases, possibly depending on the mechanism and severity of the trauma (2)
• clinical features:
  • generally occurs as a 'sexual injury'; may also occur in other situations e.g. bending the penis downwards to void with an early morning erection
  • clinically there is generally no initial pain - there is however often a loud 'crack' due to the explosive decompression of the tunica. There is instant deflation of the erection and the erection cannot be regained
  • in the few hours following the injury blood gradually seeps out of the ruptured tunica cavernosa and results in extensive bruising of the penis, scrotum and lower abdomen. At this stage there is also the development of pain - this may reflect damage to the penile nerves associated with the bruising and swelling
  • clinical examination may reveal the ‘aubergine sign’, also known as the ‘eggplant sign’ - this sign summarizes the typical findings at presentation of penile fracture and consists of penile swelling, ecchymosis and penile deviation. Note though that a patient may present atypically with a straight phallus and the majority of swelling and ecchymosis occurring in the scrotal area instead of the penile shaft (3)
    • the defect in the tunica is often palpable
    • in some patients the penile skin can be rolled over the blood clot stuck in the defect
• diagnosis:
  • generally by history and examination; some authors recommend the use of ultrasound, MRI or cavernosography (2) to confirm diagnosis - however often this may only delay treatment (1)
    • a study concerning the use of corpus cavernosography (2) concluded that in the context of men with blunt penile trauma, the clinical presentation can be misleading and may result in unnecessary surgery. The study indicated that cavernosography may be helpful in selecting the treatment approach in these cases
  • if urethral injury is suspected then a retrograde urethrogram is a useful investigation
• treatment
  • early surgical repair is considered the most appropriate treatment for penile fractures

Notes:

• if there is a partial tear of one of the layers of the tunica rather than a rupture then these patients are able to have an erection again and do not have any bruising. However the healing of a partial tear is by fibrosis and the long-term consequence of this injury may be a traumatic curvature of the penis (1)

Reference:

1. GP magazine (August 12th 2005): 29.
2. Beysel M et al. Evaluation and treatment of penile fractures: accuracy of clinical diagnosis and the value of corpus cavernosography. Urology 2002; 60 (3): 492-496
3. Singh G, Capolicchio J-P. Adolescent with penile fracture and complete urethral transection. Journal of Pediatric Urology 2005; 1(5):373-376.