Menstrual cycle-related morphometric and vascular modifications of the clitoris

The evaluation of clitoral anatomy and function is of paramount importance to understand the physiology and pathology of clitoral function. To prospectively evaluate the clitoral volumetric and vascular modifications during the menstrual cycle, and analyze their relationship with circulating hormones and nitric oxide levels. Thirty healthy eumenorrheic women were studied in different phases of the menstrual cycle (day 3, 10, 14, 20, and 27). They were submitted to ultrasonographic (US) and Doppler analyses, and to hormonal and biochemical evaluations. Transvaginal US evaluation of uterus, ovaries, and clitoris; Doppler analysis of uterine and dorsal clitoral arteries; and measurement of plasma luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol, androstenedione, testosterone, and nitrites/nitrates concentration. Sex hormone binding globulin was assayed, and free androgen index was calculated. During the menstrual cycle, FSH, LH, and estradiol changed as expected, whereas androgens did not show any significant change. The US assessment of the clitoral body volume evidenced a progressive increase with significant modifications during the periovulatory phase, after which it remained stable until day 20. Subsequently, the clitoral body volume decreased into the premenstrual phase (day 27), reaching values similar to those observed on cycle day 3. A comparable trend was observed in the nitrite/nitrate circulating values. The uterine and clitoral arteries presented significant modifications with reduced resistances in the periovulatory period. Estradiol levels resulted positively correlated with the clitoral body volume and inversely correlated with the dorsal clitoral artery pulsatility index (PI). Furthermore, the dorsal clitoral artery PI was inversely and significantly correlated with the nitrite/nitrate circulating values and the clitoral body volume.