Teaching Case

While moving his furniture this patient slipped and sustained a blunt perineal trauma with minor haematoma. After three days he was suffering from a painless partially erect penis accompanied by difficulty attaining an erection sufficient for sexual intercourse. Clinical examination showed a semi-rigid erection with soft corpus spongiosum and glans.

A penile colour ultrasound showed a defect in the left cavernosal artery with a small fistula between this artery and an adjacent cystic cavity. The surrounding venous sinusoids where dilated as seen in normal penile erection. Colour Doppler showed a turbulent flow with aliaising in the fistula and in the adjacent cavity. On spectral Doppler there was a persistent forward flow in the fistula with a low-resistance pattern with elevated PSV (>200mm/s) and high EDV.
A conservative treatment (ice application, no sexual intercourse) was chosen by the patient, clinical and sonographic re-evaluation was agreed after two months. This showed a decreased painless tumescence, a volume-reduction of the cystic cavity (7mm) and fistula flow-reduction (49mm/s). After five months there was sufficient erectile function for sexual intercourse and a further decrease in flow velocity (30mm/s) with a stable cystic cavity. Further conservative treatment was advised, Avanafil 50mg could be used when experiencing erectile dysfunction.

A. Priapism is a symptom defined as a persistent penile erection longer than 4 hours continuing beyond or unrelated to sexual stimulation. It is thought to be caused by a disturbed balance between blood inflow and outflow. The American Urological Association differentiates two main causes: high flow or non-ischaemic priapism and low flow or ischaemic priapism. Pathophysiologic processes, clinical presentation and management differ vastly between these types [1, 2].
B. High-flow priapism is mostly caused by blunt perineal trauma which causes a disruption of the cavernosal artery and initiates an uncontrolled arterial inflow into the venous sinusoids. Since venous outflow is not impaired the erection is not fully rigid and mostly painless [2]. In contrast to this ischaemic priapism, which is more frequent and almost never traumatic, is primarily a disorder of venous outflow. Patients present with painful and very rigid tumescence. Once intracorporeal pressure raises above capillary pressure, arterial blood supply is impaired and the corpora cavernosa are at risk for ischaemia. Fibrosis and definitive erectile dysfunction develop between 24 and 72 hours after onset [2]. Blood gas analysis of the corpus cavernosum shows bright red blood with high PO2, low PCO2 and normal pH in high flow priapism whereas dark acidic blood with high PCO2 value indicates ischaemic priapism [3, 4].
C. Although not strictly necessary to make the diagnosis, ultrasound is recommended [3, 4, 5]. In high flow priapism the presence and location of an arteriovenous fistula can be clearly demonstrated. This shunt shows turbulent low resistance flow with very high PSV and continuous forward flow [6]. In ischaemic priapism ultrasound shows a very low or absent blood flow (PSV <50mm/s) with high resistance pattern and often diastolic flow reversal. In more advanced stages signs of oedema or fibrosis can be seen [7].
D. High flow priapism is not an emergency, observation will result in spontaneous detumescence in 60% of patients, selective arterial embolisation is the primary treatment modality in those who require intervention [3, 4, 8]. Ischaemic priapism is a true emergency that requires urgent detumescence by drugs, percutaneous puncture or surgical intervention [4, 6].
E. As a consequence all patients presenting with priapism should be examined promptly to be able to treat those with ischaemic priapism as soon as possible. Ultrasound is an excellent tool for diagnosis and follow-up. Keep in mind, and if necessary further investigate, additional traumatic perineal, penile, scrotal or urethral lesions.