Transperineal Ultrasound Combined with Contrast-Enhanced Ultrasound Enema for Diagnosis and Surgical Planning in Rectovaginal Fistula: A Prospective Study.

Background/Objectives: Rectovaginal fistula (RVF) is a challenging condition that can substantially impair quality of life and often requires individualized surgical management. Accurate preoperative imaging is essential for identifying fistulous tracts, assessing pelvic floor involvement, and guiding surgical planning. However, conventional imaging modalities, including magnetic resonance imaging (MRI), may still have limitations in detecting small, occult, intermittently patent, or anatomically complex fistulas, particularly under static imaging conditions. This study aimed to evaluate the diagnostic performance of transperineal pelvic floor ultrasound (TPUS) combined with ultrasound contrast agent enema (UCAE) and its potential value in preoperative assessment of RVF. Methods: In this prospective single-center study, 62 women with surgically confirmed RVF were enrolled between January 2022 and April 2025. All patients underwent TPUS combined with UCAE before surgery, while subsets also underwent contrast-enhanced CT, contrast-enhanced MRI, or barium enema according to clinical indications. Imaging findings were compared with intraoperative findings as the reference standard. Fistula detection, morphological classification, size, anatomical location, pelvic floor injury assessment, and concordance between ultrasound-based surgical proposals and actual surgical procedures were systematically analyzed. Comparative analyses with conventional imaging modalities were performed based on available non-paired subgroups. Results: UCAE detected RVF in 60 of 62 patients, yielding a detection rate of 96.8%. In the available comparative cohort, UCAE demonstrated higher detection rates than conventional imaging modalities, particularly in small and complex fistulas. UCAE showed high agreement with intraoperative findings in terms of fistula morphology, size, and anatomical location. TPUS provided additional and complementary information regarding levator ani and anal sphincter injuries and yielded higher sensitivity and accuracy in pelvic floor injury assessment within the studied cohort. Ultrasound-based surgical proposals showed directional concordance with final intraoperative decisions in 88.7% of cases. No adverse events were observed during UCAE. Conclusions: TPUS combined with UCAE appears to be a safe and feasible preoperative imaging approach for RVF. By integrating fistula detection, anatomical classification, pelvic floor assessment, and surgical planning, this combined ultrasound approach may serve as a complementary imaging strategy to conventional imaging modalities, particularly for small or intermittently patent fistulas. Further multicenter studies and standardized imaging protocols are warranted to validate its clinical utility and generalizability.