The role of 3-D Ultrasonography in the evaluation of menstrual cycle-related vascular modifications of the clitoris. A prospective pilot study

Introduction: Clitoral functional modifications occur during the menstrual cycle. Aim: To prospectively evaluate, by the three-dimensional (3-D) Doppler flow analysis, the hemodynamic clitoral blood flow variations during the menstrual cycle. Methods: Fourteen young (18-35 years), eumenorrheic (menstrual cycle of >25 and 1 year) and without any sexual dysfunction (as resulted from the two-factor Italian McCoy female sexuality questionnaire ≥35) were submitted, in the early follicular (day 3-5) and in the periovulatory (day 12-14) phases of the menstrual cycle, to bi- and tridimensional ultrasonographic and color Doppler analyses of the clitoral structures. On the same days, the circulating estradiol values were assayed. Main Outcomes Measures: Two-dimensional ultrasonographic evaluation of follicular diameter and color Doppler evaluation of the dorsal clitoral arteries; 3-D power Doppler analysis of the clitoral body volume and of the indices of clitoral vascularization and blood flow; estradiol assay. Results: The mean virtual organ computer-aided analysis (VOCAL) volume of the clitoral body was lower in the follicular (0.79 ± 0.19 mL) phase with respect to the periovulatory phase (0.98 ± 0.22 mL; P <0.001); the clitoral arteries demonstrated a significant decrease of the pulsatility index (PI) from the follicular (1.75 ± 0.18) to the periovulatory phase (1.26 ± 0.21; P = 0.002); the 3-D power Doppler histogram analysis showed significant changes of the indices of vascularization and blood flow (vascularization index [VI] = 2.239 ± 1.201 vs. 3.302 ± 1.305, P = 0.001; flow index = 27.290 ± 2.454 vs. 33.620 ± 1.712, P <0.001; vascularization flow index = 0.578 ± 0.573 vs. 1.091 ± 0.461; P = 0.001) between the follicular and the periovulatory phase of the menstrual cycle. The relationship between the different parameters evidenced that estradiol is positively correlated with the VOCAL clitoral body volume (r = 0.512; P = 0.033) and inversely correlated with the dorsal clitoral artery PI (r = -497; P = 0.048) and with VI (r = 0.622; P = 0.011). Conclusions: During the normal menstrual cycle, the estrogens may, probably, influence the clitoral anatomic and vascular structures and the 3-D ultrasonography may easily and precisely demonstrate these modifications.