<unk> s are classified into four categories: *First-degree<unk> : laceration is limited to the fourchette and superficial<unk>  skin or vaginal mucosa *Second-degree<unk> : laceration extends beyond fourchette,<unk>  skin and vaginal mucosa to<unk>  muscles and fascia, but not the anal sphincter *Third-degree<unk> : fourchette,<unk>  skin, vaginal mucosa, muscles, and anal sphincter are torn; third-degree<unk> s may be further subdivided into three subcategories: *3a: partial<unk>  of the external anal sphincter involving less than 50% thickness *3b: greater than 50%<unk>  of the external anal sphincter *3c: internal sphincter is torn *Fourth-degree<unk> : fourchette,<unk>  skin, vaginal mucosa, muscles, anal sphincter, and rectal mucosa are torn *Button-hole<unk> : the<unk>  involves rectal mucosa with an intact anal sphincter complex
Perineal tear
Perineal hernia
Perianal hematoma
Rectovaginal fistula
Retroperitoneal fibrosis
Vesicovaginal fistula
Sigmoidocele
Urethrovaginal fistula