Tomographic ultrasound imaging of the pelvic floor: which levels matter most?
OBJECTIVE
Tomographic ultrasound imaging has greatly simplified pelvic floor assessment. Abnormalities of the insertion of the levator ani can be documented in a single frame. In this study we aimed to determine which levels of the levator hiatus are associated with alterations in ultrasound parameters of pelvic organ support.


METHODS
This was a subanalysis of a study conducted in 296 women seen before and after their first delivery. We analyzed postpartum changes in bladder neck descent and hiatal area as indicators of altered pelvic organ support. Tomographic ultrasound examination was performed on volumes obtained at maximal pelvic floor muscle contraction, at 2.5-mm slice intervals, from 5 mm below to 12.5 mm above the plane of minimal hiatal dimensions.


RESULTS
Two hundred and eight recruits (70%) returned for a postnatal appointment. Of these, 130 had delivered vaginally and 26 (20%) were diagnosed with an avulsion injury. An abnormality in slices 3-8 was associated with increased bladder neck descent postpartum (P = 0.038 to P = 0.001) and increased hiatal area on Valsalva maneuver (P = 0.029 to P < 0.001). This was not the case for the two most distal slices.


CONCLUSIONS
We found no association between levator ani defects observed on tomographic ultrasound imaging below the plane of minimal hiatal dimensions and indices of increased hiatal distension or bladder neck descent on Valsalva maneuver. This implies that defects observed below this plane are either irrelevant for pelvic organ support or artifactual.
Nepean Clinical School, University of Sydney, Nepean Hospital, Penrith, New South Wales, Australia. hpdietz@bigpond.com
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D000328:Adult; D001003:Anal Canal / Q000000981:diagnostic imaging; D052858:Cystocele / Q000000981:diagnostic imaging*; D036861:Delivery, Obstetric / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D007744:Obstetric Labor Complications / Q000000981:diagnostic imaging*; D017773:Pelvic Floor / Q000000981:diagnostic imaging / Q000293:injuries; D011247:Pregnancy; D014463:Ultrasonography; D014596:Uterine Prolapse / Q000000981:diagnostic imaging*