Reliability of vulvar blood perfusion in women with provoked vestibulodynia using laser Doppler perfusion imaging and laser speckle imaging

Background: Microvascular assessment has become increasingly used in gynecology to better understand the pathophysiology of various vulvar conditions and to study sexual function. Alteration in blood perfusion of the vulvar area has been observed using laser technologies in women with provoked vestibulodynia (PVD), the leading cause of vulvar pain. However, no studies have thus far investigated the reliability of and agreement between lasers for evaluating vulvar blood perfusion. Objectives: The main objective was to investigate the between-session reliability of the laser Doppler perfusion imaging (LDPI) and laser speckle contrast imaging (LSCI) for assessing blood perfusion of the vulvar vestibule in women with PVD. Secondary aims were to evaluate the association and agreement between the two laser technologies. Methods: Twenty-six women with PVD participated in the study. Blood perfusion of the vulvar vestibule was assessed with LDPI and LSCI during two sessions 2 to 4 weeks apart. Blood perfusion was analyzed in five specific areas of the vulvar vestibule: 1) 3 o'clock site, 2) 6 o'clock site, 3) 9 o'clock site, 4) central area (delimited by areas 1, 2 and 3), and 5) posterior fourchette. The reliability of the measurements of the two instruments was calculated with intraclass correlation coefficients (ICCs), standard errors of measurement (SEMs) and coefficients of variation (CVs). Paired t-tests were also computed to compare the CVs of each laser technology. The association and agreement between LDPI and LSCI measurements were evaluated by Pearson's correlation coefficients and Bland-Altman plots, respectively. Results: Excellent reliability was found for LDPI (ICCs = 0.78-0.80, p < 0.001, SEMs = 16.1-47.9) and LSCI measurements (ICCs = 0.75-0.81, p <= 0.001, SEMs = 17.0-52.2) for all vulvar vestibule areas. However, CVs were significantly higher using LDPI (CVs = 15.1-19.8) when compared to LSCI (CVs = 7.0-11.6) for all areas (p <= 0.031), except for area 4 (p = 0.079). Significant correlations were found between LDPI and LSCI for all areas (r = 0.58-0.89, p <= 0.003). Bland-Altman plots revealed a systematic difference between LDPI and LSCI measurements. Conclusion: Findings show that both LDPI and LSCI measurements are reliable for assessing blood perfusion of the vulvar vestibule in women with PVD. The LSCI appears to be a more reliable measurement as it presents less variation than LDPI. Finally, although LDPI and LSCI measurements are related, the systematic difference observed between them makes it impossible to compare absolute units.