P1186 Transperineal ultrasound is accurate in detecting perianal complications in Crohn’s disease: a systematic review and meta-analysis

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Abstract Background 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 CD (PACD). This review evaluates the diagnostic accuracy of TPUS compared with MRI, transrectal ultrasonography (TRUS), and examination under anaesthesia (EUA) for detecting and classifying perianal fistulas and abscesses. Methods A comprehensive literature search was conducted across multiple databases from their inception to December 2023 to identify studies evaluating TPUS accuracy in detecting perianal fistula and abscesses using MRI, TRUS, or EUA as reference standards. Meta-analysis was performed to assess TPUS accuracy for fistula detection (FD), fistula classification (FC), internal opening (IO) detection and abscess detection (AD) with a subgroup analysis carried out in CD patients. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate the risk of bias. Results Of the 994 studies identified, 25 (involving 1435 patients) met the inclusion criteria for the meta-analysis. These included 24 studies on FD, 11 on FC, 21 on AD and 10 on IO detection. Overall, these studies had a moderate risk of bias, with moderate applicability concerns due to high risk of bias in patient selection (non-consecutive enrollment) and reference standard chosen (non-blinding interpretation of scans). Significant heterogeneity was observed across study domains with I2 and X2 values of 98%, 88.0%, 93.0%, and 105.6, 16.0, 27.5 for FD, FC, and AD, respectively (p<0.001). Pooled sensitivities for FD, FC, IO detection and AD were 97.7%, 99.9%, 91.5% and 94.2% respectively while pooled specificities for FD, IO detection and AD were 77.8%, 73.1% and 78.6% respectively. Diagnostic Odd’s Ratio for FD, IO detection and AD were 148.13, 29.39 and 280.07 respectively. The overall accuracy of TPUS for FD, FC, IO detection and AD was 92.5%, 90.7%, 88.3% and 94.3% respectively (Table 1). A subgroup analysis focusing on CD patients (from 13 studies) showed pooled sensitivities of 96.6%, 99.9% and 85.5%, with overall accuracies of 85.2%, 86.5% and 83.4% for FD, FC and AD respectively. Stratification by publication date demonstrated improved accuracy in FD and AD in studies published after 2017 (91.6% vs 96.0% and 87.3% vs 96.8%). Conclusion TPUS demonstrates high accuracy in detecting perianal fistulas and abscesses in both CD and non-CD patients, supporting its use as a non-invasive, first-line diagnostic tool.