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 < 35 days) women in a stable heterosexual relationship (> 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.