Investigation of vascular and structural abnormalities of the penis

Since the advent of phosphodiesterase-5 (PDE-5) inhibitors, in routine clinical practice, patients presenting with ED typically do not require further investigation beyond a thorough history, physical exam, basic hematologic and biochemical laboratory analyses, and a possible hormonal assessment (if there is reason to suspect an endocrinopathy). For further information on these general evaluations, see Chapter 22; for further information on PDE-5 inhibitors, see Chapter 29. A number of additional studies exist, however, to aid the clinician in assigning a specific cause to a patient’s ED. These investigations fall into one of three categories: (i) vascular testing such as duplex ultrasound and dynamic infusion cavernosometry/cavernosography, (ii) neurological testing such as a biothesiometry, somatosensoryevoked potentials, and pudendal electromyography, and (iii) daytime and nocturnal penile tumescence and rigidity analysis. The indications for such adjunctive investigations have been controversial, but, in the authors’ experience, these are typically reserved for the following groups of patients: (i) patients who are potentially curable, including young males with purely arteriogenic ED of traumatic etiology and young males with isolated crural venous leak, (ii) patients with penile curvature who require evaluation prior to undergoing penile reconstructive surgery, (iii) patients who require documented evidence of abnormalities for medicolegal purposes, and (iv) rare patients with unclear and difficult-to-diagnose psychogenic disorders in whom evidence for normal organic function could help the patient to focus on addressing the true underlying psychosocial problem.