Trends in obstetric anal sphincter injury in spontaneous vaginal delivery versus operative vaginal delivery over a 10-year period: Lessons learned.

OBJECTIVE

To evaluate trends in the incidence of women with obstetric anal sphincter injuries (OASIS) over a 10-year period comparing spontaneous vaginal delivery (SVD) and operative vaginal delivery (OVD).

METHODS

A retrospective study was performed in which all women who underwent vaginal delivery over a 10-year period (n = 86 242, 2009-2018) at the Rotunda Hospital were reviewed. The overall incidence of OASIS was compared with incidence rates stratified by parity and type of vaginal birth.

RESULTS

The 10-year vaginal delivery rate was 69% (n = 59 187) where 24 580 women (42%) were primiparous and 34 607 women (58%) were multiparous. SVD rate was 74% and OVD rate was 26%. The overall incidence of OASIS was 2.9%. The incidence of OASIS in OVD was 5.5% and the incidence in SVD was 2%. Of 498 multipara who sustained OASIS, 366 (73%) had an SVD without episiotomy compared with 14 (3%) who had an episiotomy. There was a significant reduction of OASIS over the 10-year period in primipara who had an OVD but no reduction in the other groups.

CONCLUSION

The primiparous OVD group had a significant reduction of OASIS. Continued education around perineal protection and episiotomy at SVD could positively impact further reduction in OASIS, particularly in the SVD groups.