The rise of obstetric anal sphincter injuries (OASIS): 11-year trend analysis using Patient Episode Database for Wales (PEDW) data.

The aim of this study was to establish the trend of obstetric anal sphincter injuries (OASIS) in Wales. A retrospective search of Patient Episode Database for Wales (PEDW) data was carried out. Data were available for 11 years from 1999 to 2009. The incidence of OASIS steadily increased from 1.81% in 1991 to 5.62% in 2009 (χ(2) for trend p < 0.001), which is more than a three-fold increase. This was observed alongside a significant increase in resort to episiotomy (χ(2), p < 0.001) and forceps delivery (χ(2), p < 0.001), drop in the use of ventouse delivery (χ(2), p < 0.001) as well as increase in caesarean delivery (χ(2), p < 0.001) over the same period. This showed the incidence of OASIS in Wales to have risen significantly and steadily over the period 1999-2009. This necessitates a look to identify and deal with the cause(s) of this rise and monitor its future course.