The overall risk of obstetric anal sphincter injury is 1% of all vaginal deliveries. With increased awareness and training, there appears to be an increase in detection of anal sphincter injury. Obstetricians who are appropriately trained are more likely to provide a consistent, high standard of anal sphincter repair and contribute to reducing the extent of morbidity and litigation associated with anal sphincter injury.
Obstetric anal sphincter injury encompasses both third- and fourth-degree perineal tears:
- A third-degree perineal tear is defined as a partial or complete disruption of the anal sphincter muscles, which may involve either or both the external (EAS) and internal anal sphincter (IAS) muscles
- A fourth-degree tear is defined as a disruption of the anal sphincter muscles with a breach of the rectal mucosa
The purpose of this guideline is to provide evidence-based guidance on the diagnosis, management and treatment of third- and fourth-degree perineal tears.