Prior to 1998, cavernosometry and cavernosography were widely used for the diagnosis of male erectile dysfunction (ED). However, with the launch of a new oral drug treatment — sildenafil (Viagra ®),, the need to diagnose cavernous insufficiency has changed greatly. What was the reason for this? Quite simply stated, the treatment of erectile dysfunction was no longer a function of any testing. Rather, the introduction of the oral phosphodiesterase type 5 inhibitors (PDE-5i) changed the diagnostic and treatment paradigm. Invasive diagnostic testing was no longer required for the introduction of treatment of erectile dysfunction (ED). Essentially, if a man complained of erectile dysfunction, then he was offered a PDE-5i for his erectile dysfunction (ED). The distinction between organic and psychogenic erectile dysfunction became blurred and the etiology of the erectile dysfunction, be it arteriogenic, neurogenic or venogenic was no longer a prerequisite for treatment.
Historically, animal experiments and clinical observations in humans have demonstrated that a chronic, disturbed arterial blood supply to the cavernous tissue with subsequent hypoxemic/ischemic conditions, impaired the veno-occlusive mechanism in the long term and resulted in the symptoms of cavernous insufficiency. The severity of arteriosclerosis correlated with the severity of the veno-occlusive dysfunction. These observations led to the implementation of cavernosography and cavernosometry.
The technique, involving use of a 27-30g needle, is used to inject varying µg (microgram) doses of PGE1 (Caverject ®), or a triple drug mixture, approximately 5-15min before the actual investigation. The penile shaft is then draped with a sterile, perforated drape. Patients who are sensitive to pain receive 1-2 cm3 of a 1% local anesthetic containing lidocaine, which is infiltrated prior to insertion of the 19 g butterfly needle. The butterfly needles should be applied vertically to the penis axis to avoid needle dislocation during erection and subsequent edema. The cavernosography pump is then used to infuse pre-heated physiologic saline in 20 — 40mL/min steps until an erection considered firm enough for intercourse is achieved. The infusion is then stopped at a cavernous pressure of 150 mm Hg, and the fall in pressure within 30-60 sec is measured. The infusion is then restarted. When an erection considered firm enough for intercourse is achieved again (i.e. pressure > 90-100mmHg), the maintenance flow that is necessary to maintain a stable erection is measured.
Non-ionic contrast agent is then added via a three-way stopcock, and after 50-100 mL of contrast agent, X-ray is performed in four different planes. This includes two anterior/posterior projections with the penis bent upwards and downwards, as well as two lateral/oblique projections using the urethrogram technique. Infusion is then stopped and 300-500 µg of phenylephrine is injected intracavernosally to achieve detumescence. The butterfly cannula are removed after detumescence has occurred and the puncture sites are compressed with a sterile swab for 2-3 min. An elastic compression dressing is applied at the end of the investigation for 1-2 h.
Gravity cavernosometry, first described by Puech Leao in 1990 is a simplified method of cavernosometry/cavernosography A pump is not required for this method. Cavernous pressure is continuously measured using a manometer via one butterfly needle, and saline at body temperature is infused via the other butterfly needle. The infusion solution is placed at a gravity pressure of 112mmHg. Following injection of the vasoactive substance, intracavernous pressure is measured continuously until a plateau has been achieved (equilibrium pressure). The infusion tube is then completely opened and the maximum cavernous pressure is measured using a manometer. However, gravity cavernosometry could never establish itself against pump cavernosometry as a routine method.