Intraobserver and interobserver agreement in anal endosonography

Background: The aim of this study was to determine intraobserver and intero bserver agreement for sonographic measurements of anal canal structures usi ng anal endosonography (AES), and to determine interobserver agreement for the diagnosis of anal sphincter disruption. Methods: Fifty-one consecutive patients referred for AES for the investigat ion of possible sphincter abnormality were examined. Studies were reviewed by two observers who measured anal canal structures at defined levels and l ocations, and recorded an opinion on sphincter integrity. Repeated measurem ents made by each observer were compared to determine intraobserver agreeme nt, and measurements and diagnoses were compared between observers to deter mine interobserver agreement. Results: Intraobserver agreement was better than interobserver agreement fo r measurements of anal canal structures. Interobserver limits of agreement for external sphincter measurements spanned 5 mm, whereas those for the int ernal sphincter spanned 1.5 mm. Interobserver agreement for diagnosis of sp hincter disruption and internal sphincter echogenicity was very good (kappa = 0.80 and 0.74 respectively). Conclusion: The limits of agreement for intraobserver and interobserver mea surements of anal canal structures on AES have been defined. Interobserver assessment of sphincter disruption is very good.