Resistance index as a prognostic factor for prolonged erection after penile dynamic colour Doppler ultrasonography

To identify an objective and reliable prognostic factor for prolonged erection after penile dynamic colour Doppler ultrasonography (CDU).

From June 1995 to July 1996, 156 patients suffering from erectile dysfunction were submitted to penile dynamic CDU at our institution. From June to December 1995 (Group 1), patients with rigid erection at the end of the test were invited to wait 90 min for a review. If detumescence had not occurred at the first review, they were invited to wait another 60 min for a second review. If detumescence had not occurred at this stage, they were given an intracavernous injection (ICI) of etilefrin to induce detumescence. To test the validity of the findings obtained in Group 1, from January to July 1996 (Group 2) patients with rigid erection and resistance index (RI) < or = 1.00 at the end of penile dynamic CDU were sent home and invited to return to the hospital if erection lasted more than 2 h, while those with rigid erection and RI > 1.00 were immediately given an ICI of etilefrin to induce detumescence.

Of the 62 patients in Group 1, 31 yielded a rigid erection. Seven refused to wait for a review. They were given an ICI of etilefrin and excluded from the study. Of the 24 evaluable patients, 10 presented spontaneous detumescence at the first review. RI was < or = 1.00 in 7, and > 1.00 in the other 3. None of the remaining 14 patients presented spontaneous detumescence at the second review. RI was > 1.00 in all of them. They were successfully managed with an ICI of etilefrin. Of the 94 patients in Group 2, 43 yielded a rigid erection. Twenty had a RI < or = 1.00 and therefore were sent home. None of them returned to the hospital. Contacted by phone, they all said that spontaneous detumescence had occurred within a couple of hours. Of the 23 patients with RI > 1.00, 22 were immediately given an ICI of etilefrin. One who refused returned to the hospital 4 h later with a prolonged erection which was successfully managed with an ICI of etilefrin.

This study showed that RI is a reliable prognostic factor for prolonged erection. In patients with RI > 1.00 at the end of penile dynamic CDU, immediate prevention of prolonged erection is recommendable to avoid unpleasant sequelae.