Association between pelvic organ prolapse types and levator-urethra gap as measured by 3D transperineal ultrasound

J Ultrasound Med. 2018 Dec;37(12):2849-2854. doi: 10.1002/jum.14644. Epub 2018 Apr 19.


Objectives: To evaluate the association between pelvic organ prolapse (POP) types and levator-urethra gap (LUG) as measured by 3-dimensional transperineal tomographic ultrasound.

Methods: A retrospective study was carried out on 98 women with symptomatic POP. Three-dimensional transperineal tomographic ultrasound images and POP quantification coordinates were reviewed. Each vaginal compartment was staged for the degree of prolapse, and total number of involved compartments identified. LUG was measured on 3-dimensional tomographic sonograms as the distance between the center of the urethra and the levator insertion bilaterally. Based on prior studies, an abnormal LUG of 25 mm or greater indicated levator avulsion. The LUG and the presence or absence of unilateral/bilateral avulsions was analyzed with reference to the clinical diagnosis of prolapse (single versus multicompartment, and mild [stage II] versus severe [stage III-IV]). Generalized logit models were used to evaluate the association between avulsion and prolapse type and stage.

Results: The LUG was substantially larger in women with multicompartment compared to single-compartment POP (28.9 ± 4.1 mm versus 22.7 ± 4.1 mm, P < .01). Similarly, LUG was substantially larger in women with severe (stage III-IV) compared to mild (stage II) POP (28.8 ± 4.7 mm versus 23.3 ± 4.5 mm, P < .01). Women with severe prolapse were 32 times more likely than women with mild prolapse to have bilateral levator avulsion. Those with POP involving all 3 vaginal compartments were 76 times more likely than single-compartment POP to have bilateral levator avulsions.

Conclusions: Bilateral levator ani avulsion as diagnosed by LUG measurements of 25 mm or greater at rest is associated with multicompartment, severe prolapse.

Keywords: levator ani avulsion; levator-urethra gap; pelvic organ prolapse; transperineal ultrasound.

MeSH terms

  • Body Weights and Measures / methods*
  • Cohort Studies
  • Female
  • Humans
  • Imaging, Three-Dimensional / methods*
  • Middle Aged
  • Pelvic Floor / diagnostic imaging*
  • Pelvic Organ Prolapse / diagnostic imaging*
  • Perineum / diagnostic imaging
  • Retrospective Studies
  • Ultrasonography / methods
  • Urethra / diagnostic imaging*