Diagramatic representation shows which degree of perineal tear:

First-degree tear: Laceration is limited to the fourchette and superficial perineal skin or vaginal mucosa Second-degree tear: Laceration extends to perineal muscles and fascia, but not the anal sphincter Third-degree tear: Anal sphincters are torn Third-degree tears - Three subcategories: 3a: paial tear of the external anal sphincter involving less than 50% thickness 3b: greater than 50% tear of the external anal sphincter 3c: internal sphincter is torn Fouh-degree tear: Rectal mucosa is torn First and Second degree tears are called Paial Perineal tears. Third and Fouh degree tears are called Complete Perineal tears.