Variability of the pubic arch architecture and its influence on the minimal levator hiatus area

Abstract

Objective: To investigate the association between the minimal levator hiatus (MLH) area at rest with its surrounding soft-tissue and bony structures in nulliparous asymptomatic women with a normal levator ani muscle.

Methods: A subanalysis was undertaken of a prospective study of the appearance of the levator ani in asymptomatic nulliparous women conducted between September 2010 and September 2011. The subanalysis included women with a normal levator ani muscle. Three-dimensional ultrasonography volumes were used to obtain pelvic floor measurements.

Results: The analysis included 56 women with mean age of 43.0±13.4years. The mean MLH area was 13.1±1.8cm(2) (range 9.0-17.3). The pubic arch angle had no influence on the MLH area (Pearson correlation coefficient r=0.13). Height and pubic arch length were positively correlated with the MLH area (r=0.26 [P=0.52] and r=0.50 [P<0.001], respectively).

Conclusion: The MLH size of nulliparous women varied widely and was positively correlated with the height and pubic arch length of the women. Therefore, caution is warranted when interpreting the MLH area as an indicator of a levator ani defect or a predictor of pelvic organ prolapse without taking a woman's pelvic bone characteristics into account.

Keywords: Endovaginal ultrasonography; Levator ani muscle; Minimal levator hiatus; Pubic arch angle.