Interobserver variation in measuring the anovaginal distance (AVD) with perineal ultrasound

Aims: This study describes perineal ultrasound measurement of the AVD in regard to ease of learning and interobserver agreement, in order to establish if the method is reliable to use in further research about objective postpartum description of perineal tears.

Methods: To educate the examiners, the method was shown and described by an experienced examiner. The examiners then measured the anovaginal distance in one woman repeatedly with until similar results (+/- 5 mm ) were achieved. The woman was in the lithotomy position and a vaginal ultrasound probe was used. The AVD in another 40 women was then measured and documented by two examiners, right after the other, who were blinded to the other´s results. The distance was measured between the mucosal margin of the internal anal sphincter and the vaginal probe. Interobserver agreement was calculated using Kappa-score.

Inclusion Criteria:

Examiners; the gynecologists authoring the study

Patients:

• any women visiting the gynaecological outpatient clinic of Linköping University Hospital where a vaginal ultrasound examination was performed

Exclusion Criteria:

Examiners: n/a

Patients:

• inability to understand spoken or written Swedish

The examiners whose measurements were compared for interobserver varialility were gynecologists working inte the department.

The study population to perform measurements on was recruited from women visiting the gynaecological outpatient clinic of Linköping University Hospital.