Introduction. Blood flow parameters in cavernous arteries during full-erection phase on Doppler ultrasonography are associated with intracavernosal pressure and, consequently, with penile rigidity.
Aim. To examine the relationship between blood flow parameters in cavernous arteries and the penile rigidity.
Materials and methods. A total of 54 healthy men and patients with erectile dysfunction of various degrees of severity, with mean age of 43,0 ± 2,2 years ranging from 18 to 74 years, were included in the study. Erectile function was examined and 81 Doppler ultrasonography were performed after intracavernosal injection of alprostadil (10 mcg). In full-erection phase, peak systolic velocity (PSV) and systolic acceleration (SA) were measured, as well as resistive index (RI). Mean values were calculated for both cavernous arteries. Penile rigidity was assessed in three ways: clinical evaluation according to I. Goldstein, measurement of surface rigidity and evaluation of longitudinal rigidity.
Results. During Doppler ultrasonography a strong correlation of penile rigidity with RI (0,71-0,85) and SA (0,63-0,69) was found. Indirect assessment of penile rigidity using PSV values was less precise. With RI values close to 1,0, SA is a more reliable method for indirect rigidity assessment.
Conclusion. Penile blood flow parameters, RI and SA, allow to evaluate a degree of rigidity and to eliminate subjectivity of the specialist performing the examination, as well as to obtain a range of penile rigidity values.

Keywords: extension rigidity, surface rigidity, resistivity index, systolic blood flow acceleration, systolic blood flow velocity, Doppler ultrasonography with pharmacologic stimulation, cavernous arteries, penis