Perineal tear classification

Perineal tear classification is a system used to quantify the severity of trauma to the perineum during vaginal childbirth. Delivery may lead to overstretching of the vagina, causing tears in the perineal tissue between the vagina and rectum. Lacerations are classified into four categories:^{[1] [2]}

• First degree tear: laceration is limited to the fourchette and superficial perineal skin or vaginal mucosa
• Second degree tear: laceration extends beyond fourchette, perineal skin and vaginal mucosa to perineal muscles and fascia, but not the anal sphincter
• Third degree tear: fourchette, perineal skin, vaginal mucosa, muscles, and anal sphincter are torn
• Fourth degree tear: fourchette, perineal skin, vaginal mucosa, muscles, anal sphincter, and rectal mucosa are torn

Third degree tears may be further subdivided into three subcategories:^[3]

• 3a: partial 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

References