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    Vaginal delivery and the pelvic floor: Outcomes of levator ani injury

    Dr Hoyte is Professor, Fellowship and Division director, Female Pelvic Medicine and Reconstructive Surgery, University of South Florida Morsani College of Medicine, Tampa. He has no conflicts of interest to report with respect to the content of this article.

     

    Dr Wyman is Clinical Fellow, Female Pelvic Medicine and Reconstructive Surgery, University of South Florida Morsani College of Medicine, Tampa. She has no conflicts of interest to report with respect to the content of this article.

     

     

    Dr Hahn is Clinical Fellow, Female Pelvic Medicine and Reconstructive Surgery, University of South Florida Morsani College of Medicine, Tampa. She has no conflicts of interest to report with respect to the content of this article.

     

    Levator ani injury occurs in 3 of 10 vaginal deliveries and often results in pelvic floor dysfunction including pelvic organ prolapse and incontinence. Understanding the mechanism of injury to the muscle of the levator ani is imperative to minimizing injury with delivery. It has long been recognized that the levator ani muscle group plays a key role in female pelvic floor function.1

    When functioning normally, this muscle group has multiple roles, including support of the vagina and pelvic organs, and maintenance of urinary and fecal continence.2 The levator ani muscle complex is composed of 3 main muscle groups: the puborectal, the pubococcygeal, and the iliococcygeal portions with motor nerve input from the nerve to levator ani (S2,3,4), which courses over the ventral surface of the levator ani.3

    The levator ani muscle complex encircles the largest potential hernia portal in the human body and compromise of this muscle complex is currently the best-defined pathogenesis for pelvic organ prolapse.1 Force vectors on the muscle during distention and passage of a fetal head result in excessive strain and stretch on the muscle, increasing the chance for injury.

    During vaginal childbirth, the opening of the genital hiatus distends substantially to allow the passage of the fetus. This requires the distal-most portions of the levator ani (pubococcygeal and puborectalis) to stretch to greater than 3 times their original length, thereby putting strain on the muscles and their attachments to the pubic symphysis.4 Increased strain can result in damage or even complete disruption and detachment of the levator ani muscles from their insertion point on the pubic symphysis.

    In addition, during the second stage of labor as the fetal head descends, excess stretch and distention of the iliococcygeus portion of the levator ani results 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, thereby disrupting the motor signaling to this normally tonic muscle, possibly leading to laxity or sagging of one or both sides of the Iliococcygeus muscle.5

    The 2 childbirth-related mechanisms described above have the potential to cause significant injury to the levator ani muscle attachments and nerve supply increasing the risk of urinary and fecal incontinence and future development of pelvic organ prolapse (POP).6-8

     

    Lennox Hoyte, MD, MSEECS
    Dr Hoyte is Professor, Fellowship and Division director, Female Pelvic Medicine and Reconstructive Surgery, University of South Florida ...
    Allison M Wyman, MD
    Dr Wyman is Clinical Fellow, Female Pelvic Medicine and Reconstructive Surgery, University of South Florida Morsani College of Medicine, ...
    Lindsey A Hahn, DO
    Dr Hahn is Clinical Fellow, Female Pelvic Medicine and Reconstructive Surgery, University of South Florida Morsani College of Medicine, ...

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    • This article comes disturbingly close to encouraging women to elect Caesarian section in order to avoid pelvic floor trauma. I seriously question the idea that a forceps delivery carried out by a skilled operator leads to an increased risk of injury. ACOG's advice to require a nullip to push for 3 full hours before employing forceps is where the real problem lies. At the end of those 3 hours, the vulva, having been subjected to unrelenting pushing, is swollen to a point where tearing rather than stretching is the likely outcome. It's only reasonable to conclude that the same dynamic applies to the levator muscles. Moreover, this prolonged pushing results in distortion of the fetal fontanelles, making proper forceps application difficult and injury more likely. Dr.Joseph DeLee's classic paper, "The Prophylactic Forceps Operation" of 1920 stated correctly that this technique preserved the integrity of the pelvic floor. That was the case then and is the case today. Sadly, forceps delivery is no longer taught, which why we need so many specialists in pelvic floor reconstruction.
    • RuthMielke
      Agree with the first statement re: "coming close to recommending ECD". As a certified nurse-midwife in clinical practice for 30 years who has worked in very high volume labor settings, I challenge the statistic cited by the authors "More than 30% of all women who deliver vaginally will experience some form of direct trauma to the pelvic floor resulting in injury to their levator ani muscle". Levator ani injury: damage to said muscle - either a third degree or fourth degree perineal laceration occurs rarely- not 3 out of 10 vaginal births. There is a dearth of research that routine use of episiotomy is correlated with greater levator ani injury - Why wasn't this mentioned? Also - challenge the suggestion that pudendal/regional anesthesia may promote pelvic relaxation and prevent injury. Regional anesthesia is well-known to be associated with prolonged second stage as compared to women without it and therefore the "relaxation" hypothesis is obviated by the resulting prolonged period of perineal distention that often results. I appreciated the excellent anatomical explanation/images but wish the authors gave more consideration to actual practice e.g. < 0.5% 3rd/4th degree lacerations which I would say is typical practices if routine episiotomy is not done, and focused more on aspects of prevention that were only touched on - pelvic floor strengthening prenatally and during interconception, pre-pregnancy attention to high BMI, as such women have more genital tract trauma and larger babies etc.
    • ROBERTCWALLACH
      nicely done; better discussion than found in most texts; disappointed that seminal article by Porges,Porges, Blinick in the green journal has disappeared

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