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Int Urogynecol J. 2016 Jun;27(6):909-13. doi: 10.1007/s00192-015-2909-0. Epub 2015 Dec 9.

Is the levator-urethra gap helpful for diagnosing avulsion?

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Sydney Medical School Nepean, Nepean Hospital, Penrith, NSW 2750, Australia.
Sydney Medical School Nepean, Nepean Hospital, Penrith, NSW 2750, Australia.
División de obstetricia y ginecología, Escuela de medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
Departamento de Ginecología y Obstetricia, Clínica Alemana de Santiago-Universidad del Desarrollo, Concepción, Chile.
Departamento de Ginecología y Obstetricia, Hospital Clínico de la Universidad de Chile, Santiago, Chile.



Levator avulsion is a risk factor for female pelvic organ prolapse (POP) and recurrence after POP surgery. Imaging diagnosis requires the observation of an abnormal muscle insertion on tomographic ultrasound imaging (TUI). This study was designed to compare the diagnostic performance of the qualitative diagnosis (visual qualitative assessment) to measurement of the distance between muscle insertion and urethra [levator-urethra gap; (LUG)].


This was a retrospective analysis of data obtained in a tertiary urogynecological unit. All patients presented with symptoms of pelvic floor dysfunction and underwent 4D translabial pelvic floor ultrasound (US), supine, and after voiding. Avulsion was defined qualitatively as abnormal muscle insertion and quantitatively as LUG ≥25 mm on at least three consecutive central axial plane slices, with one examiner using both methods. We examined the correlation between both methods and validated them against clinical prolapse, significant organ descent on US, and hiatal ballooning.


Between January and July 2013, 233 patients were seen, of whom 202 had complete volume data sets. The qualitative method diagnosed avulsion in 22 % and the quantitative method in 24.3 %. Agreement was good, with a kappa of 0.79 (0.70-0.87). Avulsion diagnosed by either method was associated with clinical and sonographic prolapse and hiatal ballooning, with odds ratios nonsignificantly higher for the quantitative method.


Qualitative analysis of slices on TUI and a method using LUG measurement show good agreement for the diagnosis of avulsion. The LUG method is at least equally as valid in its capacity to predict significant prolapse on clinical examination and US, as well as ballooning of the levator hiatus.


Avulsion; Levator–urethra gap; Prolapse; Tomographic imaging; Translabial ultrasound

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