Penile Doppler ultrasonography
When is this exam indicated?
This examination is the best functional test to analyze inability to achieve or maintain an erection, and also possible reasons of vascular origin of the erectile dysfunction.
How is it performed?
Modern ultrasound scanners, equipped with wide-band and high-frequency transducers, allow to obtain ultrasound images with high spatial resolution and the increased sensitivity of color Doppler allows an excellent evaluation of penile arterial and venous vessels in normal and pathological conditions. Ultrasound study of the penis should be performed using linear transducers with a frequency of 7.5 MHz or higher. The examination is performed with the patient lying supine, evaluating the penis predominantly with longitudinal and transverse scans of the ventral aspect. After a preliminary study in flaccid conditions, we proceed to the pharmacostimulation of the erection obtained by injecting into a corpus cavernosum about 10-20 micrograms of prostaglandin E1 (PGE1). The injection is given laterally to the vasculo-nervous bundle, typically 2-4 cm dorsal to the balano-preputial groove, using a fine needle (25-27G). At this point, blood circulation within the penile vessels is examined after a phase of manual self-stimulation of the penis, performed privately by the patient. This technique aims to obtain the complete relaxation of the smooth muscles of the corpora cavernosa and then to optimize the erectile response to the vasodilator injection in order to be able to accurately assess the circulatory function of the penis. At the end of the examination, an erection of variable quality (from very reduced to completely rigid) can be obtained. In case of a very stiff erection, the patient is kept under observation for about an hour and if necessary a microinjection with a pharmacological antidote (phenylephrine) is used to facilitate the return to flaccidity. Foreseeable risks and possible complications related to the execution of this examination are: soreness at the injection site that may last a few hours, small hematoma at the injection site, or a prolonged erection. This last condition configures the picture of priapism, which if neglected can become a serious complication. For this reason, it is important that the patient does not leave the clinic without being examined by the doctor. If upon leaving the clinic the patient observes a resumption of rigid erection for more than two hours, he should then visit the emergency room for treatment.
Intolerance to the test, problems with blood pressure control, previous negative reaction to PGE1.