Penile ultrasonography
Penile ultrasonography is medical ultrasonography of the penis. Ultrasound is an excellent method for the study of the penis, such as indicated in trauma, priapism, erectile dysfunction or suspected Peyronie's disease.
Ultrasound is an imaging modality that, in addition to being well tolerated and widely available, is considered an excellent method for the evaluation of many penile diseases. Penile trauma, priapism, Peyronie's disease, and erectile dysfunction are some of the conditions in which penile ultrasound finds significant applicability.
Currently, linear transducers have a maximum frequency of 12-15 MHz, which increases the definition on ultrasound images. Although penile evaluation is usually performed when the penis is flaccid, in some situations, such as in cases of erectile dysfunction, the examination should be performed during erection, by injection of vasoactive drugs into the corpora cavernosa. The penis should be positioned in the anatomical position and evaluated in the transverse and longitudinal directions, from the glans toward the base of the penis. In specific situations, such as in the evaluation of Peyronie's disease, the penis should also be positioned on a towel/sheet or on the testicular sac, with a lateral approach.
Anatomy and physiology
The corpora cavernosa are homogeneous and relatively hypoechoic cylindrical structures lined with tunica albuginea, a thin membrane that has a thickness of approximately 2 mm when the penis is flaccid and 0.25 mm when it is erect. The corpus spongiosum, a ventral, medial body that is more echoic than the corpora cavernosa, is also covered by the tunica albuginea and contains the urethra. As can be seen in Figures 1 and 2, it is more dilated and prominent in its proximal segment, known as the bulb, and in its distal segment, constituting the glans. Buck's fascia is superficial to the tunica albuginea and covers all of the structures described.Venous drainage is performed by the deep and superficial dorsal veins of the penis. The dorsal arteries of the penis are located adjacent to the deep dorsal vein and a cavernous artery is located in the center of each corpus cavernosum. On color Doppler, the cavernous arteries present single phase flow. In the flaccid penis, the normal cavernous arteries show a systolic peak between 11 and 20 cm/s. At the beginning of erection, the systolic and diastolic flows undergo progressive increases. When vein occlusion begins, the diastolic flow decreases progressively, and once stiffness is established, it becomes negative.