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Penis Ultrasound Imaging and Doppler Sonography

Penile ultrasound is used in the diagnostic workup of a patient with erectile dysfunction, Peyronie’s disease, priapism, penile fracture, penile urethral strictures, urethral stones, urethral diverticulae and penile cancer involving deep tissues of the penis. Penile Doppler ultrasound is used in addition in patients with erectile dysfunction and priapism.

Ultrasonography of the penis (transverse section from ventral): corpora cavernosa (1+2), corpus spongiosum (3).

Ultrasonography of the penis (transverse section from dorsal): corpora cavernosa (1+2), corpus spongiosum (3), penile skin (4) and dorsal penile vessels (5)..

Examination Technique

A high-resolution linear probe of 7.5–10 MHz is used for imaging of the penis. The penis is examined longitudinally and in transversal sections with the probe on the dorsum and/or ventrum of the penis [fig. transverse ultrasound imaging from ventral and transverse ultrasound imaging from dorsal]. The tunica albuginea is a thin echogenic structure surrounding the hypoechogenic erectile tissue. The penile vessels can be identified dorsal to the tunica albuginea. The lumen of the urethra cannot be seen without injection of lubrication gel, after the injection the urethra is examined from the ventrum of the penis. Imaging of the urethra is best done with an assistant who stretches the penis to the side while injecting the lubricant, this enables the examiner to do imaging with both hands free [see section urethral stricture].

Penile Doppler Ultrasonography

The measurement of penile blood flow after pharmacologically induced erection provides valuable information about the erectile function, see section diagnostic workup of erectile dysfunction for details. The quality of erection is assessed every 5–10 min after intracavernous injection of alprostadil until full erection is achieved and a Doppler sonography of the penile arteries and veins is done. If the erection does not occur within 30 minutes, the examination will be terminated.

Measurements of Doppler sonography are done at the cavernous artery in the corpus cavernosum [fig. Penile Doppler ultrasonography (longitudinal section)]. The standard value for the peak systolic velocity (PSV) is at least 25 cm/s. At full erection, the end-diastolic velocity (EDV) in the arteries should be below 5 cm/s, higher values suggest venous leakage from the corpus cavernosum. The flow in the penile veins should also be below 5 cm/s. The RI (resistive index) is close to 1 at maximum erection because end-diastolic blood flow should near to zero. An RI below 0.75–0.8 indicates venous leakage.

Penile Doppler ultrasonography (longitudinal section) 15 min after intracavernous injection of alprostadil: tunica albuginea (1), corpus cavernosum with cavernous artery (2), corpus spongiosum (3). With kind permission, Dr. med. W. Unkhür, Augsburg.

References

  Deutsche Version: Sonographie des Penis