How valid is tomographic ultrasound imaging in diagnosing levator and anal sphincter trauma?

Objectives: Three"/four"dimensional translabial ultrasound (US) is increasingly used to image the levator ani and anal sphincters, especially in the form of tomographic US. The aim of the study was to evaluate the validity of these published methods. Methods: This work was a retrospective analysis of datasets of 172 nulliparous women who attended 2 tertiary urogynecologic centers for symptoms of pelvic floor dysfunction between June 2012 and September 2016. All patients had a standardized interview, clinical examination, and 4"dimensional translabial US examination. An evaluation of volume data was performed by the first author, who was blinded against all clinical data, including parity. An assessment for levator avulsion and anal sphincter defects was performed using stored US volume data. Results: Data sets of 162 and 153 nulliparous women were available for levator and anal sphincter assessments, respectively. On the assessment by the first author, a complete avulsion was diagnosed in 3 nulliparas. On a review by 2 senior authors, 1 was judged as positive and the other 2 as normal. On the sphincter assessment, 2 significant external anal sphincter defects were detected. On the review, 1 was judged as false"positive. The second was judged as highly abnormal by all authors. Therefore, 1 nullipara each was diagnosed with avulsion and a significant external anal sphincter defect. Conclusions: Published diagnostic criteria for levator avulsion and external anal sphincter trauma on tomographic US imaging are highly unlikely to result in false"positive findings. This finding supports the clinical validity of this method.