Second degree |
Injury to perineum involving perineal muscles but not
involving the anal sphincters |
Third degree |
Injury to perineum involving the anal
sphincter complex:
3a: <50% of ext anal
sphincter(EAS) thickness
3b: >50% EAS
thickness
3c: both EAS and internal anal sphincter (IAS)
involved
|
Fourth degree |
Involves anal sphincter complex (EAS and IAS) and
anorectal mucosa. |