pelvic floor muscle tone between women with and without pelvic pain

For what seems like months, 90% of my inquiries have been for symptoms of pelvic floor tightness. Most of these people also report having chronic pelvic pain and even though clinically I know what to do to get them on track, I couldn’t help but wonder what the research says about chronic pelvic pain conditions and the pelvic floor. 

Among the searching I came across a systematic review and meta-analysis that was published in 2023 titled ‘Is there a difference in pelvic floor muscle tone between women with and without pelvic pain?’ 

Study details → Kadah S, Soh S, Morin M, Schneider M, Heron E, Clinphys M, Frawley H. Is there a difference in pelvic floor muscle tone between women with and without pelvic pain? A systematic review and meta-analysis. The journal of sexual medicina 2023;20 65-96

Is there a difference in pelvic floor muscle tone between women with and without pelvic pain? A systematic review and meta-analysis – PubMed (nih.gov)

Chronic pelvic pain is quite a prevalent problem within women’s health not only impacting the individual but can also having a negative impact on relationships due to the associated sexual dysfunction that often comes with it. This issue alone is often the driving force behind why a woman reaches out for help.

Many of my pelvic pain clients are living with Endometriosis which is one of 4 of the conditions the paper considers a condition included in the review. The other three being:

• Vulvodynia
• Genitopelvic pain/penetration disorders (dyspareunia and vaginismus)
• Interstitial Cystitis (ICS) and bladder pain syndrome (PBS)

Everything else including cancer, pelvic floor disorders such as incontinence and pelvic organ prolapse and any history of perineal or pelvic surgery was excluded

Before we dive into the results of the review/meta analysis, there were a couple of really interesting points covered in the introduction that really stood out to me and landed a little differently when I read them.

1. Muscle tone can consist of 2 components; the active component and the passive component. 
   1. The active component being the contractile aspect of muscle tissue that is driven by the myoelectric activity.
   2. Whereas the passive components being that of its viscoelastic properties is independent of myoelectrical activity.
2. Digital palpation might be suitable for clinical practice and evaluating the pelvic floor however in research is considered more subjective in nature and does not demonstrate a level of reproducibility.

More on these 2 points later on…

The primary aim of the review was to produce the evidence relating to the difference in pelvic floor muscle tone between women with and without persistent non cancer pelvic pain (PNCPP). 

After identifying 1604 potential papers only 21 studies were included in the review that met the criteria for inclusion.

Parameters measured and reported on within this review:

• PFM tone measurements – methods included EMG, digital palpation, ultrasound imaging, MRI, dynamometry, myotonometry, manometry and strain elastography. 
• Myoelectrical activity – women with PNCPP showed a large and significantly higher degree of PFM activity compared to those without PNCPP.
• PFM Resistance – measured with digital palpation or with a speculum there was pressure applied slowly to the PFM to assess resistance. Again women with PNCPP presented with a large and significant higher degree of PFM resistance compared to those who were pain free.
• Morphometry – which included measuring various angles, levator hiatus dimensions and length of pelvic floor muscles
  • Anterior-posterior diameter of the levator hiatus – women with PNCPP had significantly smaller anterior-posterior levator hiatus distance.
  • Levator hiatus area – 4 studies measured the levator hiatus area with different PNCPP conditions, 3 of which found significantly smaller LHA.
  • PFM length – 2 studies measured the length of deep PFM and found no significant difference between women with and without pain, however one of them reported significantly shorter deep PFM in women with PNCPP. It was mentioned within the paper the discrepancy between the citations within the meta-analysis and the meta analysis results was due to the varying methods of data comparison. 
  • Anorectal angle – there was conflicting data between the studies in regard to findings of this measure
  • Levator plate angle – another measure with conflicting data between studies
  • Puborectalis angle – only 1 study measured this and it found significantly wider angle in women with PCNPP.

Due to the low number of studies reporting on the following measures a meta analysis was not conducted on these but results were reported based on studies that assessed the following:

• Stiffness of the pelvic floor – observed within the studies included in the review was higher resting PFM stiffness in women with PVD (provoked vestibulodynia) and in women with IC/BPS.
• Flexibility – All 3 studies that compared flexibility of the pelvic floor in women with and without pain found women with PVD had significantly lower flexibility than women without pain
• Pelvic floor relaxation – 2 out of 3 studies found significantly reduced ability to relax the pelvic floor in women with PNCPP and one found no difference. 
• Intravaginal pressure – 2 out of 3 studies reported no significant difference with 1 study finding women with pain had significantly higher intravaginal pressure.
• Passive component of PFM tone – only one study assessed passive tone and found significantly higher resistance and stiffness in the passive component of the pelvic floor in women with PVD compared to those who were pain free.

After reading this review it was pretty clear that most measures of the pelvic floor in women with pain were favouring tightness, stiffness and smaller levator hiatus dimensions of the pelvic floor muscles. Not surprising really.

But what else can we take from this study to apply clinically?

1. Women with persistent pelvic pain as a result of conditions such as Endometriosis, Vulvodynia, Genitopelvic pain/penetration disorders such as dyspareunia and vaginismus, Interstitial Cystitis (ICS) and bladder pain syndrome (PBS) are all prone to pelvic floor tightness. Whether or not pelvic floor tightness contributes to pain in these conditions has not been thoroughly researched. However I know from clinical experience that addressing pelvic floor tightness, as step number one in an exercise program, before working through deep core retraining and functional movement, has drastically improved pain symptoms in many of my clients who are living with Endometriosis, Vulvodynia and IC. If you see clients with these persistent pelvic pain conditions and are not including pelvic floor release, relaxation and retraining within your treatment I would highly recommend you begin including this. It makes such a difference!
2. Within the discussion of this paper they refer to one particular paper that caught my interest. A paper that compared 2 different PFM conditions and found women with vaginismus had significantly higher PFM tone than women with PVD indicating that there may in fact be differences in tone across the varying PNCPP conditions. Is this something research could dive into further that can guide clinicians who may not have access to internal assessments.
3. There are many parameters that influence the pelvic floor muscle tone and with a proper assessment and understanding of how these parameters are impacted by certain PNCPP conditions we can tailor a more effective intervention to help our clients. This might look like better relaxation of the pelvic floor if myoelectrical activity and resistance is high versus more focus on decreasing stiffness in those with smaller hiatal dimensions, more stiffness and a lack of flexibility. We could be utilising dynamic stretching in these people with less focus on muscular relaxation. When I really sat down and thought about this point it took me back to a few of my clients with pelvic pain conditions. Pelvic floor symptom presentation varied between them and also their ability to feel what was happening in their pelvic floor. Some reported being able to successfully relax their pelvic floor whilst others didn’t. I now wonder which parameter of pelvic floor muscle tone was more impacted by their PNCPP condition, the active or passive component?
4. The paper suggests that internal palpation as a form of assessment is more subjective in nature rather than objective which made me feel over the moon. Not because I don’t think it’s great but because clinically it feels like any report writing to GP’s or specialists requires objective measures and this can feel impossible to do when we assess clients in pelvic health. So even though an internal assessment may provide more insight into different parameters it will always rely heavily on the experience and skillset of the examiner and will be based on their subjective assessment. The review itself mentions the importance of establishing normative values and thresholds of increased pelvic floor muscle tone that is considered problematic in order to guide clinicians with their assessments and determinations.

That was a BIG one! 

I do try and keep these quick and to the point but this one was a heavy read!

I hope you have found this valuable and excited to learn more about helping clients with persistent pelvic pain or even how to incorporate more programming specific to pelvic floor tightness within your current practice.