Transperineal Ultrasound for Perianal Fistulas and Abscesses – A Systematic Review and Meta-Analysis

Abstract

Purpose Transperineal ultrasound (TPUS) is a practical tool for assessing perianal inflammatory lesions. We systematically review its accuracy for detecting and classifying perianal fistulae and abscesses.

Method The National Library of Medicine and Embase were searched for articles on TPUS for the assessment of idiopathic and Crohn’s perianal fistulae and abscesses. Two reviewers independently reviewed eligible studies and rated them for quality using the QUADAS tool. The primary outcome measure was the accuracy of TPUS as measured by its sensitivity and positive predictive value (PPV) in detecting and classifying perianal fistulae, internal openings and perianal abscesses.

Results We included 12 studies (565 patients). Overall, the methodological quality of the studies was suboptimal. 3 studies were retrospective and 4 showed significant risks of bias in the application of the reference standard. The sensitivity of TPUS in detecting perianal fistulae on a per-lesion basis was 98 % (95 % CI 96 – 100 %) and the PPV was 95 % (95 % CI 90 – 98 %). The detection of internal openings had a sensitivity of 91 % (95 % CI 84 – 97 %) with a PPV of 87 % (95 % CI 76 – 95 %). The classification of fistulae yielded a sensitivity of 92 % (95 % CI 85 – 97 %) and a PPV of 92 % (95 % CI 83 – 98 %). TPUS had a sensitivity of 86 % (95 % CI 67 – 99 %) and PPV of 90 % (95 % CI 76 – 99 %) in the detection of perianal abscesses.

Conclusion The current literature on TPUS illustrates good overall accuracy in the assessment of perianal fistulae and abscesses. However, many studies had methodological flaws suggesting that further research is required.

Zusammenfassung

Ziel Der transperineale Ultraschall (TPUS) ist eine Untersuchungsmethode zur Bewertung von entzündlichen perianalen Läsionen. Wir überprüfen systematisch dessen diagnostische Genauigkeit in Bezug auf Nachweis und Klassifizierung von Perianalfisteln und –abszessen.

Methoden Die „National Library of Medicine and Embase“ wurden auf Artikel über TPUS zur Beurteilung von perianalen Fisteln und Abszessen (idiopathisch und bei M. Crohn) untersucht. Zwei Gutachter überprüften unabhängig voneinander geeignete Studien und bewerteten deren Qualität dem QUADAS Werkzeug. Der primäre Endpunkt war die Genauigkeit des TPUS, ausgedrückt durch Sensitivität und positiver Vorhersagewert (PPV) in Bezug auf Nachweis und Klassifizierung von Perianalfisteln, inneren Öffnungen und perianalen Abszessen.

Ergebnisse Wir schlossen 12 Studien (565 Patienten) ein. Insgesamt gesehen war die methodische Qualität der Studien suboptimal; 3 waren retrospektiv und 4 hatten ein signifikantes Bias-Risiko bezüglich der Anwendung von Referenzstandards. Die Sensitivität des TPUS beim Nachweis perianaler Fisteln auf Läsionsbasis betrug 98 % (95 % CI: 96 – 100), der PPV war 95 % (95 % CI: 90 – 98). Bei der Erkennung innerer Öffnungen zeigte sich eine Sensitivität von 91 % (95 % CI: 84 – 97) und ein PPV von 87 % (95 % CI: 76 – 95); Die Klassifizierung von Fisteln ergab eine Sensitivität von 92 % (95 % CI: 85 – 97) und einen PPV von 92 % (95 % CI: 83 – 98). Eine Sensitivität von 86 % (95 % CI: 67 – 99) und ein PPV von 90 % (95 % CI: 76 – 99) hatte TPUS beim Nachweis von Perianalabszessen.

Schlussfolgerung Die aktuelle TPUS-Literatur zeigt eine insgesamt gute Genauigkeit bei der Beurteilung von Perianalfisteln und -abszessen. Allerdings hatten viele Studien methodische Mängel, was darauf hindeutet, dass weitere Forschungsarbeiten erforderlich sind.

Key Words

anus - fistula - abscess - perianal - ultrasound - meta-analysis

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