Evaluation of regiscan reliability in assessing potency status prior to nerve sparing radical retropubic prostatectomy (NS-RRP)

In order to clarify the reliability of current available penile tests to correlate with potency status, sixteen consecutive potent patients were evaluated before NS-RRP using: 1) a detailed questionnaire of patient and partner sexual habits; 2) penile biosthesiometry; 3) Rigiscan testing for three nights; and 4) Duplex Doppler scanning of the cavernosal arteries before and after intracorporeal injection of PgE1. Three patients had moderate erections by questionnaire. The other thirteen were normal (age ranging from 47 to 70, with median of 61). Penile biosthesiometry correlated quite poorly with potency status with 9 patients being normal (56%). Continuous nighttime monitoring of penile tumescence and rigidity was interpreted using accepted standards. Of thirteen patients who completed the testing, only four potent patients (31%) had normal Rigiscan studies whereas three others were normal but discontinued monitoring after two nights because of pain or discomfort during sleep. Eight Rigiscan tests were abnormal: tip-base dissociation in two patients, and short periods of rigidity in six. Duplex scanning demonstrated excellent peak velocities (>25 cm/sec; average 43 cm/sec) and a normal erection with PgE1 in thirteen potent patients, while lower peaks and a weak to moderate erection were obtained in the remaining three. Thus, the duplex doppler results were well correlated with the patient's and partner's evaluation of potency status. As more insight is obtained regarding postoperative sexual function of patients after NS-RRP, this limited well-studied prospective series underscores the need for careful preoperative assessment of these surgical candidates. Among the available penile tests, the Rigiscan appeared to correlate very poorly with patient's potency status. Duplex Doppler scanning, combined with the intracorporeal injection of PgE1, correlated best with reported potency status.