METHODS
All patients with major OASIS (defined as Grade IIIb, IIIc or IV by the
Sultan classification [4]) in a single birthing unit over a two year
period underwent endoanal ultrasonography (B&K, Denmark) at 6-12 weeks
post-surgical repair (Group A). Surgical repair was performed by a
specialist consultant under anaesthesia (general or spinal) using an
overlapping technique if possible, otherwise an approximation technique
was used. Any ultrasonographic gap or discontinuity for any vertical
length, or horizontal width, in the anal sphincters was scored as a
defect. The defect was scored separately for internal anal sphincter
(IAS) or external anal sphincter (EAS). The endosonographic assessment
was blinded to the ultimate faecal incontinence scores obtained at a
later date.
At 1-3 years after the obstetric event these patients were sent a
questionnaire designed to allow extraction and calculation of the Wexner
faecal incontinence score (Figure 1). We defined Wexner score of ≥ 9 as
significantly affecting quality of life. [8] The Vaizey score was
not used because of the integral use of ability to defer defaecation in
this score, which would introduce considerable overlap with the presence
of IBS complaints. However, the ability to defer defaecation longer than
15 minutes was included as an item in our questionnaire. The
questionnaire also allowed us to calculate the presence and type of IBS
based on the Rome IV criteria (Figure 2). Other variables that were
collected were age, parity and mode of delivery, body mass index (BMI).
Two control groups were included, and these were aimed to be of equal
size to Group A. The first control group consisted of primigravid women
(Group B) who filled out a questionnaire at their first consultation of
a midwife or obstetrician in the first trimester of their pregnancy. The
second control group were women who underwent an elective Caesarean
section (Group C) who filled out a questionnaire at a minimum of 12
months post-partum. Exclusion criteria were previous anal surgery,
previous obstetric sphincter injury, inflammatory bowel disease and
coeliac disease.
Statistical analysis was done with SPSS version 24 (IBM, USA). For
comparison of binary variables Chi quare test was used, for intra-group
comparison of mean (SD) Wexner scores a t-test was used and for
inter-group comparison of mean (SD) Wexner scores ANOVA was used. Format
of data presentation was deliberately chosen to suit subsequent clinical
usefulness. The study protocol obtained ethical approval from the local
health district.