=Perineal Lacerations.= A large proportion of women during the birth of the first baby sustain some degree of perineal laceration, which may amount to nothing more than a nick in the mucous membrane, or it may extend entirely across the perineal body and tear through the rectal sphincter. The causes of these tears are generally conceded to be rigidity of the perineal muscles; disproportion between the size of the child’s head and the vulval opening; a sudden expulsion of the child’s head, before the perineum is fully distended, and certain abnormalities in the mechanism of labor. Lacerations may, therefore, be prevented, or limited, in many cases by holding back the baby’s head and allowing it to dilate the perineum slowly. But in spite of the most skillful and careful efforts, tears of some degree occur in most primiparæ, and probably in half of all multiparæ. These injuries are usually described as being of the first, second or third degree, according to their extent. =A first degree tear= is one that extends only through the mucous membrane, usually at the margin of the perineum, without involving any of the muscles. =A second degree tear= is one that extends down into the perineal body and may involve the levator ani, or even extend down to, but not through the rectal sphincter. Such a tear usually extends upward on one or both sides of the vagina making a triangular injury. =A third degree tear= extends entirely across the perineal body and through the rectal sphincter and sometimes up the anterior wall of the rectum. This variety is often called a =complete tear=, in contradistinction to those of first and second degree, which are incomplete. It is a fairly general custom to repair these lacerations at the time of labor, no matter what their extent, the sutures being introduced but not tied, during the third stage. The patient is usually sufficiently anesthetized to permit of this, without further anesthesia, in all but complete tears, and as there is usually but very slight bleeding before the expulsion of the placenta, the field is comparatively clear and the stitches are easily put into place. They are not tied, as a rule, until after delivery of the placenta because of the strain which its expulsion would put upon the fresh stitches. In all but very slight tears, the doctor will usually want the patient turned across the bed, with her hips brought to the edge, and her legs supported in the lithotomy position. As the few instruments necessary for perineal repairs should be boiled and placed in readiness before labor, there is usually no further preparation for the nurse to make, and the perineal dressing, after the stitches have been taken, is ordinarily the same as that following a normal delivery. (See Fig. 80 for necessary instruments.)