Comparison of retrograde CT pneumovaginography with positive CT vaginography in the assessment of the lower urogenital tract in female dogs

Introduction / Purpose: Computed tomography (CT) is commonly used to investigate pathologies of the urogenital tract in female dogs. Even though positive contrast medium is frequently used, negative contrast medium has proven valuable in the assessment of urinary pathologies. The aim of this study is to compare the use of CT pneumovaginography with positive CT vaginography in the assessment of the lower urogenital tract in female dogs. Methods: This retrospective method comparison study gathered 30 cases retrieved from the database of three referral hospitals and equally divided them into two groups: positive contrast CT-vaginography group and CT-pneumovaginography group. Criteria for inclusion in the current study were CT images of diagnostic quality with intravenous post-contrast injection, vaginography, and complete patient history. The degree of visibility of seven anatomical urogenital structures was blindly scored from 0 to 2 by two board-certified radiologists. A mean was established between both observers. The agreement between both readers was assessed with Cohen's kappa statistics. Positive and negative contrast vaginographies were compared using Wilcoxon tests. Results: The agreement between readers was near perfect to moderate for the vagina and the external urethral orifice. A significant grading difference was observed for only two structures: the cervix (p-value=0.000592) was better visualized on positive vaginography whilst the external urethral orifice (p-value=0.02136) was better identified on negative vaginography. Discussion / Conclusion: Both techniques offered similar quality for most of the scored structures. CT pneumovaginography is a valuable alternative technique to positive CT vaginography to assess the lower urogenital tract in female dogs.