=Laceration through the Sphincter Ani, involving the Recto-vaginal Septum.=--In case the recto-vaginal septum has been torn, it may be necessary to repair the tear before operating on the perineum and the sphincter ani muscle. In some cases the laceration extends for three or more inches up the septum (Fig. 40). The edges of the septal tear should be denuded, the strip of tissue being cut away to the line of normal rectal mucous membrane. Annoying bleeding may occur if the mucous membrane of the rectum is injured. The denudation may be extended on the vaginal aspect as far as is necessary to obtain a sufficiently broad surface for approximation. The tear in the septum should be closed by interrupted sutures introduced from the vaginal aspect. The suture is passed through the vaginal mucous membrane at about an eighth of an inch from the edge of the wound, and emerges in the edge of the rectal mucous membrane. It should not pass through the rectal mucous membrane. [Illustration: FIG. 41.--Denudation. Sutures introduced to close the laceration of the recto-vaginal septum.] [Illustration: FIG. 42.--Laceration of the recto-vaginal septum closed. The operation is completed by the introduction of sutures as in Fig. 38.] After the sutures in the recto-vaginal septum have been shotted, the operator may proceed to repair the perineum and the sphincter ani muscle (Figs. 41, 42). There is a variety of perineal laceration (between the first slight median laceration and the second complete laceration through the sphincter ani) in which only the outer fibers of the sphincter muscle are injured. In this injury partial incontinence results. The woman may be able to control feces when the movements are hard, but loses control over liquid feces and flatus. There is no loss of support of the pelvic floor, and the indication for operation is the partial incontinence. The operation is performed in a way similar to that already described for complete laceration. The ends of the ruptured fibers of the sphincter muscles are usually indicated by a slight depression on the overlying skin or mucous membrane. =Laceration in One or Both Vaginal Sulci.=--In this form of injury the tear takes place not in the median line, but in the direction of the vaginal sulci or furrows. The left sulcus is usually the more deeply torn.