Perineal lacerations can be divided into three degrees according to the degree of laceration, as follows:
1I° perineal laceration: Perineal skin and mucosal laceration, including labial and vestibular mucosal rupture.
2II° perineal laceration: Perineal skin, mucosa, and muscle laceration, but the anal sphincter is intact.
3III° perineal laceration: Occurs during the second stage of labor, when the fetal head is crowning, the pregnant woman may feel a tearing sensation in the perineal area. Immediate discovery of III° laceration and suture after delivery. Due to the varying degree of rupture, the symptoms can be mild or severe, such as if the anal sphincter is only partially torn, then it can only be uncontrollable when the stool is loose. In this case, the patient tries to make the stool dry. The control of stool mainly relies on the anal sphincter, so that the stool does not suddenly overflow when the abdominal pressure increases, but the autonomous control of stool response not only relies on the sphincter, but also relies on the levator ani. Severe cases cannot control even dry stool, and the vulva is often contaminated with stool.