Clinical meaning
The perineum is the diamond-shaped region between the pubic symphysis anteriorly, the coccyx posteriorly, and the ischial tuberosities laterally. The obstetric perineum specifically refers to the area between the vaginal introitus and the anus, which is the site of episiotomy incision. The perineal body is a fibromuscular structure at the center of the perineum where several muscles converge: the bulbospongiosus, the superficial and deep transverse perineal muscles, the external anal sphincter, and portions of the levator ani (pubococcygeus). This convergence point gives the perineal body its critical role in pelvic floor support, urinary continence, fecal continence, and sexual function. An episiotomy is a surgical incision through the perineal body performed during the second stage of labor to enlarge the vaginal outlet. Two types are recognized: median (midline) episiotomy, which is cut from the posterior vaginal fourchette directly toward the anus along the midline, and mediolateral episiotomy, which angles 45-60 degrees from the midline toward the ischial tuberosity. Median episiotomies are easier to repair and cause less blood loss and postpartum pain, but carry a significantly higher risk of extension into...