Pelvic floor (Levator ani) injury occurs in 3 of 10 vaginal deliveries and often results in pelvic floor dysfunction including pelvic organ prolapse and incontinence.
The pelvic floor muscles is consist of three main muscle groups: the puborectal, the pubococcygeal, and the iliococcygeal. The main function is to support the vagina and pelvic organs, and maintenance of urinary and fecal continence.
During vaginal childbirth, the opening of the genital hiatus distends substantially to allow the passage of the fetus. This stretches the pelvic floor muscle greater than 3 times their original length, thereby putting strain on the muscles and can result in damage.
In addition, during the second stage of labor as the fetal head descends, excess stretch and distention of the muscles result in stretch and distention of the nerve to the levator ani. Prolonged stretching of this motor nerve has the potential to permanently damage the nerve, leading to laxity or sagging of one or both sides of the Iliococcygeus muscle.
The above two labor related mechanisms have the potential to cause significant injury to the pevic floor muscle attachments and nerve supply, leading to an increase risk of urinary and fecal incontinence and future development of pelvic organ prolapse (POP).
The prevention for pelvic floor dysfunction may be reduced by pelvic floor education and exercises during and after pregnancy. In one study, women who received pelvic floor therapy from 20 weeks’ gestation were less likely to report urinary incontinence in late pregnancy, at 3 months and 6 months postpartum. It appears that routine pelvic floor education or referral to pelvic floor physical therapy during the intrapartum and postpartum period may be beneficial, especially in high-risk patients.
- Dietz HP. Pelvic Floor trauma in childbirth. Aust N Z J Obstet Gynaecol. 2013;53:220-230.
- Dietz HP, Lanzarone V. Levator trauma after vaginal delivery. Obstet Gynecol. 2005;106:707–712.