The determinants of minimal levator hiatus and their relationship to the puborectalis muscle and the levator plate

Abstract

Objective To determine the muscles comprising the minimal levator hiatus.Design Cross-sectional study.Setting The University of Oklahoma Health Sciences Center, USA.Population Eight female fresh frozen pelves and 80 nulliparous women.Methods Three-dimensional endovaginal ultrasound was performed in eight fresh frozen female pelves. The structures of the levator hiatus were tagged with needles and the cadavers were dissected to identify the tagged structures. A group of 80 nullipara underwent 3D endovaginal ultrasound, and the minimal levator hiatus area, puborectalis area, and anorectal angle were assessed, and normal values were obtained.Main outcome measures Anatomic borders of minimal levator hiatus and normality in pelvic floor measurements.Results The pubococcygeus forms the inner lateral border and anterior attachment of the minimal levator hiatus to the pubic bone. The puboanalis fibres are immediately lateral to pubococcygeus attachments. There are variable contributions of the puborectalis fibres lateral to the puboanalis attachment. The posterior border of the minimal levator hiatus is formed by the levator plate. Eighty community-dwelling nulliparous women underwent 3D endovaginal ultrasound. The median age was 47 years (range 22-70 years). The mean of minimal levator hiatus and puborectalis hiatus areas were 13.4 cm 2 (±1.89 cm 2 SD) and 14.8 cm 2 (±2.16 cm 2 SD). The mean anorectal and levator plate descent angles were 156°(±10.04°SD) and 15.9°(±8.28°SD).Conclusion Anterior and lateral borders of the minimal levator hiatus are formed mostly by pubococcygeus. The puborectalis, pubococcygeus, and iliococcygeus form the bulk of the levator plate.

Levator plate descent correlates with levator ani muscle deficiency

“…It is known that there is a moderate correlation between ultrasound detected LAD and pelvic organ prolapse . Normal ranges of MLH area, LPDA and ARA measurements with EVUS in normal nulliparous women has been reported previously . Mean of MLH area, LPDA, and ARA in normal nulliparous women were 13.6 cm 2 , 15.9°, and 156.8°, respectively.…”

“…It has been shown that lack of adequate pelvic organ support is associated with changes in static and dynamic shape of pelvic floor . The detailed anatomy of the levator plate as it relates to the levator ani muscle subdivisions has been reported . Furthermore, using EVUS the LAD score's relationship to pelvic organ prolapse severity has been reported .…”

Interobserver agreement of multicompartment ultrasound in the assessment of pelvic floor anatomy

“…Studies have shown that images obtained using EVUS have good-to-very good correlation in cadaveric sections for pelvic floor muscle subdivisions. 10,39 Post-processing of the images acquired on 3D-EVUS facilitates the evaluation of LAM in the plane of minimal hiatal dimensions, and good-to-excellent correlation has been reported in the LH measurements. 8 A recent publication has studied the change in LH dimensions using 3D high-frequency EVUS 1 year before and after treatment for POP and found that in contrast to conservative management, there is a significant decrease in LH dimensions 12 months following surgery.…”

Is there a correlation between levator ani and urethral sphincter complex status on 3D ultrasonography?

“…These two major components of the 'continence control system' function separately [25] and may compensate one another to maintain continence [10,26]. Normal urethral support system requires the contraction of the levator ani muscle which supports the urethra through elevation of the pubocervical fascia [27]. During a cough, there is simultaneous contraction of the levator ani muscle, the diaphragm and abdominal wall muscles to build abdominal pressure.…”