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Article Review: Intrapartum Risk Factors for Levator Trauma

Intrapartum Risk Factors for Levator Trauma KL Shek and HP Dietz British Journal of Obstetrics and Gynaecology 2010

News spread quickly across the internet last week that epidurals may help prevent pelvic organ prolapse. A paper just published in the British Journal of Obstetrics and Gynaecology (BJOG) claims that avulsion (tearing away) of pelvic floor muscles from the pubic bones provides the link between vaginal delivery and pelvic organ prolapse.

The study was authored by Hans P. Dietz, MD, leading researcher of pelvic floor “microtrauma” using translabial ultrasound, which places an abdominal curved array transducer on the perineum.1 This is the latest in a series of imaging strategies used to detect “irreversible traumatic overdistention of the levator hiatus.”2

John DeLancey, MD, pioneered research using magnetic resonance imaging to locate “gaps” believed to exist between the sides of the pubic bones and the muscles that have ripped away from them. In 2007 DeLancey told us:

“The identification of discrete injuries to the muscles and connective tissues that lead to pelvic organ prolapse is needed to improve our understanding of the pathophysiology of prolapse and to develop strategies of prevention.”3

Direct trauma to the insertion of the puborectalis muscles on the sides of the pubic bones is said to occur in 15-35% of women who give birth vaginally, almost always results in cystocele, and is “very likely related to crowning of the fetal head.”4 In 2008 Dietz stated:

“To date, there have been no attempts at developing preventive strategies aimed at reducing the prevalence of female pelvic organ prolapse. Such strategies should be a high research priority, given the fact that in the USA alone over 250,000 surgical procedures are carried out each year for prolapse.”5

That year he was already testing his “prevention” strategy:

“This finding opens up novel opportunities for prevention because levator avulsion is likely to be a useful intermediate outcome variable for intervention studies. Any change in clinical practice resulting in a reduced prevalence of levator avulsion, detectable a few weeks or months after childbirth by palpation or imaging, would be expected to have a positive effect on the prevalence of significant prolapse later in life. We are currently undertaking two randomized controlled trials aimed at reducing the incidence of levator avulsion in childbirth, using antenatal intervention strategies.”

However, prevention is not all that was motivating Dr. Dietz:

“It is probable that the presence of such defects reduces the likelihood of successful surgical correction of prolapse. Consequently, diagnosis of such defects is likely to be clinically useful and may help in directing surgical technique, e.g. as regards the decision to use modern meshes such as the anterior compartment transobturator implants.”6

Dietz is a consultant for American Medical Systems and Continence Control Systems, manufacturers of transvaginal mesh. He is also a paid speaker for General Electric Medical Ultrasound and several other transnational surgical supply corporations.

Whether translabial ultrasound can actually yield accurate assessment of pelvic floor defects is debatable, as Dietz himself elucidates:

“Although single-slice representations of the puborectalis muscle are clearly insufficient to give an impression of the entire craniocaudal extent of the insertion of the muscle on the pelvic sidewall, rendered volumes of the puborectalis can easily be manipulated to show a defect where there is none in reality. This is partly due to the non-Euclidean, i.e. warped, nature of the levator plate.”7

The midwifery community was up in arms over the study. An overwhelming body of evidence points to epidurals, supine position and increased duration of the second stage of labor as direct causes of maternal injury. The illogical doublespeak contained in this study reveals a remarkable level of confusion about the birth process, which BJOG blatantly published as legitimate:

“Among the various intrapartum obstetric factors, only use of intrapartum epidural and the length of second stage were significantly associated with irreversible overdistention or microtrauma. An intrapartum epidural appeared to have a protective effect, but the longer the length of second stage, the higher the likelihood of microtrauma. As intrapartum epidural is commonly linked to prolonged second stage, one wonders whether it is the duration of active second stage rather than the duration of the whole second stage that matters in the pathogenesis of levator microtrauma. It is plausible that it is the active pushing in labour that distends and compresses the pelvic floor more forcefully, causing neuromuscular or vascular injury. Intrapartum epidural may be beneficial by preventing premature pushing. Another potential explanation may be a degree of levator relaxation in women with dense epidurals, because a paralyzed muscle is less likely to suffer trauma, given a certain degree of distention.”

Every study cited in this review assessed for muscle damage weeks or months postpartum. It is common for women to develop symptoms over this same time period, rather than immediately after delivery. If true avulsion is responsible for the majority of postpartum prolapse cases, why does it take so long for symptoms to arise? Likewise, why are these women able to reverse the symptoms of prolapse by adopting Whole Woman™ posture?

Rather than avulsion causing prolapse, it is far more likely the opposite is true: that over postpartum weeks and months a heavy, distended, malpositioned bladder stretches the dense, fibrous tissue connecting pelvic floor muscles to the pubic bones. Thinning of muscle and fascia seems far more plausible than complete tears, and would conceivably show up on ultrasound images as dark or “absent” areas.
Large numbers of women continue to suffer from OBGYN’s distorted view of the female reproductive system. Technologies such as MRI and ultrasound can be manipulated to “prove” something that doesn’t exist. DeLancey himself reveals the remarkable and dangerous truth of reconstructive surgery:

“Current surgical approaches are based upon hypotheses regarding what defect has occurred (midline, paravaginal, apical support loss), yet reliable and reproducible assessments of these defects have not been possible.”8

Levator avulsion is just one more conjecture in gynecology’s long game of smoke and mirrors.

Notes:


1 Dietz H Simpson J Does delayed child-bearing increase the risk of levator injury in labour? Australian and New Zealand Journal of Obstetrics and Gynaecology 47: 491-495 2007

2 Shek K Dietz H Intrapartum risk factors for levator trauma British Journal of Obstetric and Gynaecology. 2010

3 DeLancey J et al Comparison of levator ani muscle defects and function in women with and without pelvic organ prolapse. Obstetrics & Gynecology 109(2): 295-302 2007

4 Dietz H Kirby A Shek K Bedwell P Does avulsion of the puborectalis muscle affect bladder function? International Urogynecology Journal 20: 967-972 2009

5 Dietz H Simpson J Levator trauma is associated with pelvic organ prolapse. British Journal of Obstetrics and Gynaecology 115: 979-984f 2008

6 Dietz h Shek C Validity and reproducibility of the digital detection of levator trauma. International Urogynecology Journal 19: 1097-1101 2008

7 Dietz H Shek Tomographic ultrasound imaging of the pelvic floor: which levels matter most? Ultrasound Obstetrics and Gynecology 33: 696-703 2009

8 Larson K Hsu Y Chen L Ashton-Miller J DeLancey J Magnetic resonance imaging-based three-dimensional model of anterior vaginal wall position at rest and maximal strain in women with and without prolapse. International Urogynecology Journal 21: 1103-1109 2010

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