Perineal lacerations can be divided into three degrees according to the degree of laceration, as follows:
1. Degree I perineal laceration: Perineal skin and mucosal laceration, including the labia and vestibular mucosal rupture.
2. Degree II perineal laceration: Perineal skin, mucosa, and muscle laceration, but the anal sphincter is intact.
3. Degree III 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 and suture of degree III laceration after delivery. Due to the varying degree of rupture, the symptoms may vary in severity. If only part of the sphincter is torn, it may only be unable to control diarrhea 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, which does not cause the stool to overflow suddenly when the abdominal pressure increases. However, the voluntary control of stool response not only relies on the sphincter but also on the levator ani muscle. Severe cases may not be able to control dry stool, and the vulva is often contaminated by stool.