Provoked vestibulodynia (PVD) is defined as a “provoked vestibular pain of at least 3 months duration, without clear identifiable cause, which may have potential associated factors” [1]. This highly prevalent condition is the main cause of dyspareunia and is associated with a significant psychosocial burden [2]. However, its pathophysiology is still unclear, which may explain the lack of effective treatments. Among the proposed contributing factors, increased tone in the pelvic floor muscles was shown to be involved in PVD [3]. Due to mechanical pressure, this tensed musculature may possibly interfere with blood flow, which may, in turn, promote inflammation and increase pain sensitization. No studies thus far have investigated whether women with PVD would present a reduction in peripheral blood circulation in the dorsal clitoral artery, a branch of the pudendal artery irrigating the vulvar area. Therefore, this original research aimed to evaluate and compare the dorsal clitoral blood flow in women diagnosed with PVD and healthy controls using color Doppler ultrasonography.

This cross-sectional study involved 20 women diagnosed with PVD according to Friedrich`s criteria and 21 healthy controls. A trained evaluator blinded to the participant’s diagnosis performed the assessments of dorsal clitoral artery blood flow using color Doppler ultrasound. Participants were asked to abstain from sexual activities 24 hours prior to the exam. The evaluation was performed in the morning, during the follicular phase (from 1st to 3rd day of menstrual cycle), in a room with temperature set at 22 ºC. After a 10-min rest period in a supine lying position, the blood flow of the dorsal clitoral artery was assessed using the color Doppler ultrasound (Voluson, 730 Expert; linear transducer 3-8 MHz). The measures of the resistance index (RI), time-averaged maximum velocity (TAMX), peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI) were performed at rest considering the mean value of three consecutive waveforms. Mann-Whitney tests were used to compare blood flow parameters and student t-tests were used to compare sexual function between the two groups.

Participants with PVD and healthy controls were comparable for socio-demographic characteristics. They were predominantly white (75.6%), non-smokers (85.4%), nulliparous (46.3%) and aged 31 (±9) years old. Patients with PVD obtained a lower score for sexual function index, according to FSFI (mean total score = 16.9±7.5, p≤0.05). When compared to controls, women diagnosed with vulvodynia showed increased values for RI (PVD: median 0.72 [0.59; 0.84] vs. control: median 0.64 [0.51;0.66], p=0.003). The PVD group also had higher values for PSV (PVD: median 11.44 [9.27;15.2] vs. control: median 8.13 [7.66;8.7], p<0.001); TAMX (PVD: median 5.8 [4.33;6.74] vs. control: (median 5.26 [3.91;5.28], p=0.02) and EDV (PVD: median 3.22 [2.21;5.17] vs. control: median 3.17 [2.08;3.2], p=0.17). No statistically significant difference was found in PI between the two groups (p>0.05).

Our findings showed that women with PVD had higher values in most doppler parameters compared to controls, which are consistent with restriction in blood flow. Higher RI and TAMX values observed in women with PVD reflects a lower blood flow and a higher downstream vascular resistance. This resistance to blood flow can be explained by a vasoconstriction or a distal occlusion. Consistent with these results, higher velocities (PSV and EDV) were observed in women with PVD and could be explained by the interrelation between velocity and area of the blood vessel. According to the following formula (Flow = Velocity x Area), resistance distal to the measurement site and vasoconstriction (i.e. reduction of the area) could be counterbalanced by an increase in velocity. In sum, our findings suggest a lower blood flow in women with PVD which could play a role in the pathophysiology of PVD. It is plausible that this blood perfusion restriction may be related to pelvic floor muscle tensions.

Findings of the present study contribute to advance the understanding of the pathophysiology of PVD by unveiling a novel contributing factor. Future studies should be undertaken to further investigate the association between blood flow restriction and women’s symptomatology.

Bornstein J, Goldstein A, Coady D; International Society for the Study of Vulvovaginal Disease (ISSVD), International Society for the Study of Women’s Sexual Health (ISSWSH), International Pelvic Pain Society (IPPS). 2015 Consensus terminology and classification of persistent vulvar pain. Obstet Gynecol. 2016 Apr;127(4):745-51.
Morin M, Binik YM, Bourbonnais D, et al. Heightened Pelvic Floor Muscle Tone and Altered Contractility in Women With Provoked Vestibulodynia. J Sex Med 2017;14:592-600.
Gates EA, Galask RP. Psychological and sexual functioning in women with vulvar vestibulitis. J Psychosom Obstet Gynecol 2001; 22:221.