Preventing serious tears: Midline episiotomies cause, not prevent, serious tears. Tears into the anus or upper vagina almost never occur in the absence of midline episiotomy. In the sole trial in which women were randomly assigned* to liberal or restrictive use of midline episiotomy, of the 58 women experiencing tears into the anus or upper vagina, only one occurred on its own, rather than as an episiotomy extension (12). Anyone who has ever snipped a piece of cloth in order to tear off a length will understand why this should be so. Mediolateral episiotomies neither cause nor prevent tears (3).
* randomized controlled trial -- In a randomized controlled trial, participants are assigned by chance to the treatment group versus a standard care or no treatment - control -- group. Randomized controlled trials produce the strongest research evidence.
Preventing overstretching or injury to pelvic floor muscles, ligaments, and nerves: The pelvic floor is a complex group of muscles that form a hammock suspended between the pubic bone in front and the base of the spinal column in back. The urethra, vagina, and anus all pass through it. Pelvic floor weakness or injury can lead to:
- Sexual dysfunction (unsatisfactory sexual relations)
- Urinary stress incontinence (leakage of urine when there is a sudden increase in abdominal pressure, such as when you cough, laugh, sneeze, or lift a heavy object)
- Anal incontinence (gas incontinence, urgency, or fecal incontinence)
- Uterine prolapse (the uterus sags into the vagina)