Transperineal ultrasonography in detecting penetrating perianal disease: a systematic review and meta-analysis

BACKGROUND AND AIMS: Perianal complications such as fistulas and abscesses are common in Crohn's disease (CD) and contribute to significant morbidity. Transperineal ultrasonography (TPUS) has emerged as a non-invasive and accurate method for perianal fistulizing CD (pfCD). This review evaluates the diagnostic accuracy of TPUS compared with magnetic resonance imaging (MRI), transrectal ultrasonography (TRUS), and examination under anesthesia (EUA) for detecting and classifying perianal fistulas and abscesses.

METHODS: A comprehensive literature search was conducted across multiple databases through January 2025 to identify studies evaluating TPUS accuracy in detecting perianal fistulas and abscesses compared with MRI, TRUS, or EUA as the reference standard. Meta-analysis was performed to assess TPUS accuracy for fistula detection (FD), fistula classification (FC), internal opening (IO) detection, and abscess detection (AD). The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate risk of bias.

RESULTS: Of 1059 studies identified, 29 were included in this review. Pooled sensitivities for FD (18 studies, 1474 patients), FC (11 studies, 585 patients), IO detection (six studies, 481 patients), and AD (16 studies, 1276 patients) were 97.5%, 80.3%, 89.6%, and 93.5% respectively while pooled specificities for FD, IO detection, and AD were 69.0%, 66.3%, and 94.5% respectively. The overall TPUS accuracy for FD, FC, IO detection, and AD was 88.0%, 88.6%, 77.8%, and 91.8% respectively. Subgroup analysis on CD patients showed an accuracy of 86.4%, 87.6%, and 83.3% for FD, FC, and AD respectively.

CONCLUSIONS: TPUS demonstrates high accuracy in detecting perianal fistulas and abscesses, supporting its use as a non-invasive, first-line diagnostic tool.