(A) Fourth-degree laceration. (B) The torn anal mucosa is repaired using a running stitch, but interrupted stitches are also acceptable. (C) The internal anal sphincter should be properly identified and repaired as a separate layer. (D) The external sphincter is then identified and repaired. The repair consists of either end-to-end or overlapping plication of the disrupted external anal sphincter and capsule using interrupted or figure-of-eight sutures.