Positive and Negative Retrograde Computed Tomographic Vaginography Studies Offer Similar Visibility of the Anatomy of the Lower Urogenital Tract in Female Dogs with Urogenital Signs

Computed tomography is commonly used to investigate pathologies of the lower urogenital tract in female dogs. Even though a positive contrast medium is commonly used, negative contrast has proven to be a valuable tool in the assessment of urinary pathologies. This study aims to compare the use of negative with positive retrograde CT vaginography in the assessment of the lower urogenital tract in female dogs. This retrospective method comparison study gathered 30 cases retrieved from the database of three referral hospitals and equally divided them into two groups: positive CT vaginography group and negative CT vaginography group. Criteria for inclusion were CT images of the entire urogenital tract before and after intravenous contrast agent injection, followed by retrograde vaginography. The degree of visibility of seven anatomical structures from the fossa clitoridis to the cervix was blindly scored from 0 (nonvisible) to 2 (well visible) by two board-certified radiologists. The agreement between the two readers was assessed using Cohen's kappa statistics. Positive and negative vaginographies were compared using Wilcoxon tests. The agreement between readers varied between structures. A significant difference in grading was observed for the cervix, which was better visualized with positive vaginography (p-value = .0006), and the ostium of the urethra, which was more conspicuous on negative vaginography (p-value = .02). Both techniques offer similar visualization on most of the structures analyzed. Negative retrograde computed tomographic vaginography is a valuable and alternative technique to positive CT vaginography to assess the lower urogenital tract in female dogs.