Coronal Plane Assessment for Levator Trauma

Levator avulsion is a major etiological factor of pelvic organ prolapse (POP) and is primarily diagnosed on tomographic axial plane imaging. Two-dimensional imaging can also image the levator. The objective was to test reproducibility and validity of coronal plane assessment for diagnosis of levator trauma by assessing the coronal plane obtained on tomographic ultrasound imaging.

A retrospective study of women who had undergone an interview, POPQ and four-dimensional translabial ultrasound at a tertiary urogynecological unit. Post-processing of archived volume data was performed for assessment; and levator muscle area and estimate of remnant muscle mass in the coronal plane. Interobserver reproducibility of the latter two measures and associations between various measures of levator trauma and POP were tested.

Interobserver agreement was good for percentage estimates (ICC 0.743), but fair for area measurements (ICC 0.482). Six hundred and twenty four women were seen, 468 (75%) had significant clinical prolapse. Full levator avulsions were diagnosed in 137 (22%). Mean TTS was 2.7 (range 0-12). On coronal plane assessment average muscle area was 1.47 (SD 0.76) cm² and 1.55 (SD 0.74) cm² on the right and left, respectively (P = .005). It was 76% and 79% for average estimates of muscle mass (P = .021). Both measures were strongly associated with POP; however, they were not superior to TTS in predicting POP.

Coronal plane assessment in volume data is reproducible and valid for evaluation of levator trauma. Muscle mass estimate may be a better measure than muscle area.