Can diastasis recti cause pelvic floor disorder, or is diastasis recti simply associated with pelvic floor disorder, or neither?
These are the questions that have consumed me the last few days. Why? Beats me. It’s like an uncatchy song stuck in my head.
Nevertheless, the questions are important. If diastasis recti (DRA) can CAUSE pelvic floor disorder (PFD), treatment is pressing. If diastasis recti is ASSOCIATED with pelvic floor disorder, treatment for each needs to address both the DRA and the PFD, even if we don’t know the exact reason for the association. If it neither causes nor is associated with pelvic floor disorder, fruitless effort to correct PFD via treating DRA can be abandoned, and vice versa.
Is Diastasis Recti Associated with Pelvic Floor Dysfunction?
I’ll focus on the easiest question because the burden of proof is lowest. Proving causation is hard and proving a negative is thorny.
Thus, we ask, “Is diastasis recti ASSOCIATED with pelvic floor dysfunction?” Based on some statistics another source had quoted, I had assumed yes, absolutely. After reading some studies, I’ve learned assumptions can be misleading…
I’ll start with an oft cited study. It is called “Prevalence of diastasis recti abdominis in a urogynecological patient population”(from 2007).
I focused on this study because I was hoping, probably even assuming, they had separated women by c-section and vaginal birth to see if the DRA was associated with PFD or if DRA plus vaginal birth showed a higher association with PFD (In other words, if more women with both a DRA and PFD had ALSO given birth vaginally to their babies).
Sadly, the researchers didn’t answer this question. I’ll assume they were trying to thwart me. Obviously.
This study retroactively looked at the charts of 547 women who had sought care from a urogynecologist. In the abstract, the authors noted:
Fifty-two percent of the patients examined presented with DRA. Patients with DRA were older, reported higher gravity and parity, and had weaker pelvic floor muscles than patients without DRA. Sixty-six percent of all the patients with DRA had at least one support-related pelvic floor dysfunction (SPFD) diagnosis. There was a relationship between the presence of DRA and the SPFD diagnoses of stress urinary incontinence, fecal incontinence, and pelvic organ prolapse.
Okay, fine. We can conclude DRA is associated with PFD.
But wait, let’s look more closely at the study. You might be surprised by what it says. I know I was.
They hypothesized a physical cause for this correlation.
Because of the synergistic relationship between the pelvic floor and abdominal muscles, a decrease in abdominal muscle function associated with DRA could affect the performance of the pelvic floor musculature.
That’s a really interesting and plausible hypothesis. BUT… it wasn’t actually teased out by the researchers. Wouldn’t you need to control for the type of birth (vaginal versus c-section) before jumping to these conclusions?
What did they say about c-sections?
They noted that abdominal surgery was associated with a higher rate of DRA, but didn’t specify whether that means c-section. Though, looking at their charts, I think this is what they meant. Unfortunately, they didn’t focus (to my knowledge) on the c-section versus vaginal birth question.
The relative percentage of DRA was higher among c-sections, but the total number of patients who gave birth vaginally was much higher than those who had c-sections. Therefore, even though the rate of DRA among c-sections was higher, the overall number who had vaginal births and seemingly had pelvic floor problems was higher. And, of course, some had both c-sections and vaginal births. Additionally, more women have vaginal births than c-sections in the general population, which further muddles the question.
My point: this is a complicated question they don’t spend much time on, but it seems really really important if they are trying to isolate the association of DRA on PFD. Luckily, a 2016 study, this one prospective, addressed the c-section question. I’ll get to that study later.
Defining Diastasis Recti
Looking retroactively at women’s charts is fraught. You can easily adjust your search parameters to find what you want to find. Even the best researchers are susceptible to data mining, especially in a sample that is self-selected (all the women had already sought treatment for PFD). To be fair, the authors addressed this self-selection limitation, and I’m not saying they mined the data.
However, I do want to question the DRA inclusion parameters. They defined DRA as ANY GAP between the rectus abdominis. This means they included women with 0.5, 1, and 2 finger-widths in their diagnosis of DRA. No wonder they found that 52% of the urogynecological patient population had DRA. That’s a wide net.
If you look at their numbers, out of the 281 women classified with a DRA, 212 of them had a DRA of 2 finger-widths or less. This means only 69 had a DRA 3 and greater.
If they had narrowed the definition of a DRA to a gap wider than 2 finger-widths, as physical therapists often do, only 13%, not 52%, would have had a DRA. That’s a pretty big difference. Even if they had included women with a gap of 2 finger-widths, only 32% would have had a DRA. Changing the definition of DRA dramatically changes the conclusions.
Why did they include any gap as a DRA? Is this the going definition or did they want to make their evidence more compelling? Food for thought.
Even so, what is more intriguing is that so many women were found to have no gap, not even half a finger-width? That’s pretty amazing considering other studies show nulliparous women with an average gap of 1 finger-width.
Leaving aside the DRA inclusion parameters, their data on strength of pelvic floor muscle contraction is interesting. Oddly at the lowest level of muscle contraction (0), a higher percentage of women DID NOT HAVE A DRA than did.
But overall, the percentage of women with a DRA AND a weak muscle contraction was slightly higher than the percentage of women without a DRA AND a weak muscle contraction. This could indicate a connection between a DRA and a weak pelvic floor.
Lamentably, this connection wasn’t broken down by size of the DRA, which makes a difference when 0.5 finger-widths and 5 finger-widths were in the same DRA pot.
Also, an association can’t answer why. For example, if a woman had a baby vaginally and had a DRA from carrying around that baby, the baby, not the DRA, is the joining factor.
Similarly, they hypothesized about why age, higher parity, hormone replacement, etc.. would be causing the DRA that would be affecting the PFD without noting that these are independent risk factors for urogynological problems. Association with DRA may have been coincidental (in other words, noise).
The most interesting thing about this study is a throw away paragraph:
There have been only a few studies that suggest a relationship between abdominal muscle function and the SPFD diagnoses of interest in the current study. Three case reports of outcomes after an abdominoplasty documented resolution of UI [33–35]. In a study of children who had hypoplastic abdominal walls (prune belly syndrome), those who underwent an abdominoplasty procedure reported improvement in bowel and bladder voiding . These studies, when taken together, suggest that repair of impair- ments of the abdominal muscles results in an improvement in symptoms of UI and FI.
I’ve learned my lesson about drawing too many conclusions from tangentially related studies, but if a tummy tuck can affect UI, this does indeed provide some evidence of the structural connection. I did find one recent study showing the relationship between tummy tucks and SUI, which is promising, but the authors thought the reason had something to do with how the tummy tuck was performed and not with just closing the gap. Therefore, the structural relationship between DRA and pelvic floor disorder is still an open question.
Why Would Diastasis Recti be Associated with Pelvic Floor Dysfunction?
The evidence for the association is not as “robust” as I had assumed. Nonetheless, the association is still plausible.
Here are two possible reasons:
These reasons are not mutually exclusive.
One: The synergy of the pelvic floor and inner abdominals
Perhaps a DRA prevents this co-contraction, and the pelvic floor muscles do not automatically stiffen against the downward pressure of the TvA.
Some other studies have shown automatic activation of the internal obliques (IO) as well, which makes sense because the TvA and IO are intimately connected.
Additionally, the study showed that drawing in the lower abdomen (TvA and IO) caused similar force closures of the urethra as did contracting the pelvic floor muscles. This would mean the nervous system coordinates the force closure if it feels pressure from above.
The implications of the study are limited because it only included 7 subjects (!) and all were healthy, so this doesn’t say much about unhealthy subjects.
But it does highlight the connection between the abdominals and the pelvic floor. Theoretically, a DRA could compromise activation of the TvA and IO, which wouldn’t trigger the nervous system to contract the pelvic floor.
OR, perhaps women with a DRA have weak pelvic floor muscles that can’t close the urethra, meaning the correlation of DRA and PFD is there without a clear causation. Interesting question.
Although this was not a DRA study, the connection between the abdominals and pelvic floor is relevant.
Therefore, DRA and PFD could be related because a DRA inhibits the feedback mechanism between the pelvic floor and abdominals.
Two: Or, the correlation between DRA and PFD may only be circumstantial.
The overlapping variable—pregnancy and childbirth—may be more important than the feedback mechanism in explaining the connection. A large baby can cause DRA. A large baby can cause PFD. Ergo, the large baby, not the DRA per se, causes PFD.
Put simply, the reason you got a DRA is connected to the reason you got a pelvic floor disorder. You had a baby.
Plausibly, the correlation is a combination of both reasons, structural and circumstantial.
Stage Left: An Awesome Prospective Study Enters with Some Answers
As you can see, the evidence for an association between diastasis recti and pelvic floor disorder is pretty weak. We have one so-so study that found a connection and a bunch of theoretical ideas about why they would be connected. But that’s not enough evidence to warrant pronouncements that diastasis recti causes pelvic floor disorder, or even pronouncements that they are connected.
A prospective study would help clarify. The difference between prospective evidence and retrospective evidence is the difference between Swiss chocolate and Necco wafers (if you prefer Necco wafers, I don’t understand you). Prospective studies are better, way better. They decide upon their parameters before they begin and then follow women through a set time period. This greatly limits inaccuracies or unintentional bias that can creep into retrospective evidence.
Thus, I was delighted when Kari Bo, Guvner Hilde, et al. published “Pelvic Floor Muscle Function, Pelvic Floor Dysfunction, and Diastasis Recti Abdominis: Prospective Cohort Study.” A prospective and blinded study asking the exact question that has been taking up too much space in my mind! Egads!
The authors compared vaginal resting pressure and pelvic floor muscle strength/endurance in 300 nulliparous women with and without diastasis recti at 21 weeks of pregnancy and 6 weeks, 6 months, and 12 months postpartum. They also checked for urinary incontinence and pelvic organ prolapse. The physical therapists checking the women’s anatomy were blinded to any symptoms. Oh, and DRA was classified as anything over 2 finger-widths, so none of this “any gap goes” nonsense.
They found no association. And not only did they find no association, the women with a DRA had stronger pelvic floors whilst pregnant compared to women without a DRA.
Some physical therapists wedded to the DRA causes prolapse theory might get all doomsday and hypothesize that the DRA was causing the pelvic floor to work too hard, hence the stronger readings in the DRA women because all the pressure going downward, etc… They might even hypothesize that stronger pelvic floor readings in the pregnant DRA women was a sign of pressure systems being “off.” And if they are really cheeky, they could argue that even though the DRA women had stronger pelvic floors initially, they are still doomed to prolapse and weaker pelvic floors later on.
Therefore, let’s be clear, the postpartum numbers don’t support this possible negative spin on the data.
After pregnancy, there was no significant difference between rates of urinary incontinence or prolapse between the DRA and non-DRA groups (with the exception of higher rates of prolapse 6 weeks postpartum in the group with NO diastasis recti, although this later evened out. Maybe not having a DRA sent too much pressure downward? Oh, I don’t know. I’ve learned not to jump to conclusions).
Also, diastasis recti was not more common among those who had c-sections. I know a lot of women think c-sections raise the risk of DRA, and I’ve wondered about that, but this study didn’t find a connection.
Interestingly, a low BMI and higher exercise activity pre-pregnancy and during pregnancy at 21 weeks did correlate with a higher risk of DRA. I guess this means stop exercising and get as fat as possible before becoming pregnant. I’m kidding. Don’t do that. (Plus, this was just at the 21 week mark, the time when DRA correlated, ironically, with a stronger pelvic floor).
The authors summarized their findings:
Contradictory to the hypothesis, VRP, PFM strength, and endurance were better in women with diastasis recti abdominis than in women without diastasis at mean gestational week 21. Further, no signiﬁcant differences in PFM function were found between women with or without diastasis at 6 weeks, 6 months,and 12 months postpartum.
They also had something to say about the 2007 study I talked about earlier:
The hypothesis that women with diastasis recti abdominis may have less PFM strength and endurance is based on the assumption that the abdominals and the PFM are both part of the abdominal canister and therefore the two muscle groups are closely related through the intra-abdominal pressure. Spitznagle et al. hypothesized that if the abdominal muscles are weak or damaged as in diastasis recti abdominis, the abdominal wall cannot co-contract effectively during the PFM contraction and the PFM contraction may therefore be less effective. Our results did not support this hypothesis and our results were opposite of those reported by Spitznagle et al.
Although this study calls into question accepted “facts” about the relationship between diastasis recti and pelvic floor disorder, it doesn’t mean the two can never ever be connected. They looked at women having their first baby, not at middle aged women with multiple births under their belt. Perhaps the connective tissue becomes more compromised as women age and this can in turn affect the pelvic floor. Or, perhaps that ever illusive synergy between the abdominal and pelvic floor muscles is lost with age. Additionally, maybe the consequences of childbirth on the pelvic floor don’t show up until later.
Nonetheless, the null findings support my favorite sentence of the entire study: “Until more research is available, clinicians should use caution when postulating associations between PFM, pelvic ﬂoor dysfunctions, and the abdominal muscles.”
Physical therapists and personal trainers, stop telling women their DRA will give them prolapse or make them incontinent! Just stop. No one knows that yet.
What Should Women Do with this Information?
First, recognize that diastasis recti and pelvic floor disorder may not be directly correlated, but this doesn’t mean you can’t have both (I do), and it doesn’t mean you should stop taking your pelvic floor into consideration when trying to narrow a diastasis recti.
Then, focus on your own body.
Try This on Yourself
Lie on your back and pull-in your lower abdomen. Don’t suck it in or pull-in forcefully.
Picture a string connecting the two sides of your pelvis (hips) and pretend like you are drawing the end points of the string together.
Can you feel a co-contraction of the pelvic floor?
If you have DRA or PFD, the co-contraction might falter. In that case, you want to mentally contract the pelvic floor in and up first, and then feel it lift into the lower abs. Now they are contracting with each other, which is technically against each other (the pelvic floor is contracting against the pressure of the abdomen).
As always, talk to an actual gynecologist or physical therapist about your specific situation, especially if you know you have a DRA, but don’t know as much about your pelvic floor (bellies are easier to notice than vaginas, for obvious reasons).
In the meantime, practice your ascending contractions (starting from the pelvic floor and moving up) and be careful not to simplify the relationship between diastasis recti and pelvic floor disorder.
As with most things, our bodies and the evidence don’t tell a tidy story.
- Spitznagle, Leong, Van Dillen.“Prevalence of diastasis recti abdominis in a urogynecological patient population.” In International Urogynecology Journal and Pelvic Floor Dysfunction 2007 Mar;18(3):321–8. ↩
- Another study called “Prevalence of diastasis recti abdominis in the population of young multiparous adults in Turkey” looked at 95 patients between the ages of 19–24 and found a positive correlation between parity and DRA (meaning, as number of babies went up, so did DRA. ↩
- Ruth Sapsford, Bartron Clarke, Paul Hodges,The effect of abdominal and pelvic floor muscle activation patterns on urethral pressure,” in World Journal of Urology, June 2013, Volume 31, Issue 3, pp 639–644. ↩
- Dalia M. Kamel Ali A. Thabet Sayed A. Tantawy and Mohamed M. Radwan, “Effect of Abdominal Versus Pelvic Floor Muscles Exercises on Vaginal and Leak Point Pressures in Mild Stress Urinary Incontinence in Obese Women,” in Life Science Journal, 2011;8(4) ↩