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Updated: Sep 25, 2026

Anogenital Distance and Perineal Measurements of the Pelvic Organ Prolapse (POP) Quantification System
Published on: September 20, 2018
Changes in anal anatomy following vaginal delivery revealed by anal endosonography
A Frudinger1, S Halligan, C I Bartram
1Intestinal Imaging Centre, Department of Obstetrics and Gynaecology, Northwick Park and St. Mark's NHS Hospitals Trust, Harrow, Middlesex, UK.
Objective:
To investigate changes in anal canal anatomy following vaginal delivery in women without apparent sphincter injury.
Design:
Prospective controlled observational study.
Setting:
District general hospital.
Population:
Consecutive parous and nulliparous women attending a gynaecology outpatient clinic.
Methods:
All women were examined using anal endosonography, and parous subjects without apparent sphincter injury compared with age-matched nulliparous controls to determine any differences in general anal canal morphology.
Main Outcome Measures:
Individual anal canal components were measured at defined levels and subjects compared with controls.
Results:
Twenty-one of 54 parous women had no anal sphincter scar. Compared with nulliparous women, they had significant anterior sphincter thinning (mean 3.7 mm vs 4.6 mm, P< 0.01) in association with lateral external sphincter thickening (mean 7.0 mm vs 4.4 mm, P<0.01), and longitudinal muscle thickening (mean 2.8 mm vs 2.1 mm, P< 001).
Conclusions:
Specific changes in anal morphology have been demonstrated following vaginal delivery in women without apparent sphincter injury.
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