Presentation
Perineal trauma on a metal bar 9 days ago with onset of priapism 4 days ago. No spontaneous pain, minor to moderate pain only on palpation.
Patient Data
Doppler ultrasound of the perineum and the penis shows a large left arterio-cavernous fistula in the perineal region, underlying a small skin bruise behind the left scrotum. The fistula is probably from the dorsal artery of the left penis in the perineal region. Suspected small pseudoaneurysm 3 mm in diameter just proximal to the fistula. High flow in the left corpus cavernosum in the perineal region. More distally in the penis, no significantly increased vascularization in the corpora cavernosa.
Two weeks later, follow-up ultrasound showed persistence of the fistula. In consultation with pediatric urologists, decision was made to attempt endovascular embolization.
Diagnostic arteriography with a 4 Fr hydrophilic catheter was performed for both internal iliac arteries and superselective arteriography of the left internal pudendal and left common penile artery with a high-flow microcatheter. There are several tiny distal branches of the left common penile artery supplying the arterio-cavernous fistula causing the high-flow priapism. Embolization was performed with gelatin sponge pledgets injected through the microcatheter.
Clinically, there persists a priapism which is however less than pre-embolization.
By Doppler, clear decrease in flow on the embolized left arterio-cavernous fistula.
However, there are still Doppler signs of a small persistent left arterio-cavernous fistula with turbulent arterial flow in the left corpus cavernosum with maximum velocity of 45 cm/s and a resistive index of 0.63 (compared to the normal right contralateral side: maximum velocity of 24 cm/s and resistive index of 0.92.)
Case Discussion
In children without underlying illnesses such as sickle-cell disease, priapism is most often high-flow (i.e. non-ischemic), generally due to blunt perineal trauma. On Doppler ultrasound, it is crucial to evaluate the perineal region because most fistulas will be in this region rather than the penile shaft where less experienced imagers might intuitively look.
Conservative management, including attempting perineal compression and/or ice application for acute cases, can be sufficient in some cases. For failed conservative management after a few weeks, endovascular embolization can be attempted. In the litterature, various agents have been described, including autologous blood clot, gelatin sponge pledgets, polyvinyl alcohol particles, microspheres, coils and glue. Experience in pediatric patients is limited.
On arteriography, even for experienced interventional radiologists, it can be difficult to distinguish between the physiological bulbo-spongiosal blush and a small fistula.
This patient initially had full detumescence a few hours after embolization, but a much less marked priapism (on clinical exam and Doppler ultrasound) recurred 2 weeks after embolization. At the time of writing, conservative follow-up is ongoing and another embolization session might ultimately be performed depending on patient evolution.