What is retrograde menstruation and why does it sound so scary?

By Nikki Michelsen

Oct 3, 2022

What is retrograde menstruation and why does it sound so scary?
I’m assuming that, while you may not have heard of retrograde menstruation, you have heard of Mercury retrograde. If you’re a human on the internet, you’ll have been subject to countless memes about it, irritated tweets by folks wishing it would end already, and people who cannot take responsibility for their actions blaming it for all their problems. For the uninitiated, this is when Mercury, for a period of time, appears to be going backwards from the vantage point of Earth. Retrograde menstruation is… not the same, because unlike Mercury, something actually does travel backwards. It’s essentially describing what happens when menstrual fluid travels backwards into your body during your period, instead of being expelled onto pads, tampons, and unsuspecting bed sheets. Menstrual fluid is released through the fallopian tubes (which are porous) into the pelvic cavity. 
Retrograde menstruation is thought to occur in up to 90% of menstruating women.
Very little research has been conducted into what causes retrograde menstruation (look, I’m gonna start a drinking game where y’all have to go back and read all the articles I’ve ever written for ohne. Every time I write that there’s been ‘not enough research’ done on literally any issue mostly pertaining to women, take a shot. You’ll be wasted by the third page). However, one of the causes of menstrual fluid flowing backwards is thought to be asynchronous contractions. Typically, most of your menstrual fluid (which is made up of blood, cervical mucus, endometrial tissue, and vaginal mucus) flows easily through your open cervix and out of the vagina. This flow is helped along by the contractions of your uterus.
Since retrograde menstruation occurs in the majority of women and doesn’t appear to be consistently causing problems, many researchers reckon it should just be considered a normal part of menstruation. It won’t normally be ‘diagnosed’ unless it is causing other problems – such as severe pelvic pain or within the context of an endometriosis evaluation.
Retrograde menstruation is identified when menstrual fluid is found inside the pelvic cavity.
It’s worth noting that women with blocked Fallopian tubes have been found to not show signs of retrograde menstruation – again, Fallopian tubes are porous, which essentially means shit can get through ‘em – so if these little passages/doorways/rabbit holes are blocked, retrograde menstruation cannot occur.
If we want to be simplistic about it, we could suggest that the ‘cause’ of retrograde menstruation is that the Fallopian tubes aren’t super good at keeping any gravity-defying fluid inside the uterus/dropping out the vagina. But that’s a bit like saying that the ‘cause’ of having 50 parrots in your kitchen is that the door was left open. It doesn’t explain why 50 parrots were on your quiet cul-de-sac in Surrey in the first place. There’s still no universally accepted reason for why all of your menstrual fluid doesn’t just leave your body through the path of least resistance.
Retrograde menstruation is associated with period pain, or dysmenorrhea… but so are a lot of issues and conditions so it’s about as helpful as knowing that having a uterus is also associated with period pain (not wrong, but doesn’t really tell you anything you can use, ya know?). What is good to know, however, is that it’s perfectly normal for women to experience varying degrees of retrograde menstruation and have absolutely no idea – so don’t go thinking that your period pain means you’re experiencing unusual levels of retrograde menstruation.
Any menstrual fluid, including endometrial tissue, can drain through the body naturally.
There’s no established treatment for retrograde menstruation as, again, it shouldn’t be considered a problem unless it’s connected to another condition or illness. Which brings me to…
Some research has suggested that there could be links between retrograde menstruation and Endometriosis. Even though the majority of women do experience retrograde menstruation and the majority of women – luckily – do not have Endometriosis, it’s theorised that this could be because most bodies are able to clear this tissue so it doesn’t deposit on the organs. If the body is unable to clear it then this could be where the fluid implants upon the organs and develops as endometrial tissue. It’s important to note that this is just one of many theories of the cause of Endometriosis and doesn’t explain how some cis men (yes, really) or women who have had hysterectomies develop Endometriosis. Since there’s also no known correlation to be found between the development or severity of Endometriosis with age, the likelihood of Endometriosis being caused by retrograde menstruation is thrown into question. If it was the cause, surely the likelihood of a menstruating person contracting it would increase with age, due to the exposure to retrograde menstruation increasing with every menstrual cycle. Another theory posits that while retrograde menstruation isn’t necessarily the cause of Endometriosis, it may be a trigger of sorts in people who are predisposed to the condition. Again, not enough research has been done yet (take a shot!)
Now, who wants to take a little detour into space with me? Of course you do. Everyone knows any article is made about 12 times better with a space reference wormed in, so I’ve found one for ya. Way back in the dark ages (okay, the 1980s) when NASA had yet to send a woman into space, menstruation was a major concern for NASA. The same NASA who asked Sally Ride (the first American woman in space, nbd) if she’d need 100 tampons for a week in space were also terrified that space would break the menstrual cycle. Like, without gravity, would periods still flow out of the body? Would they just float like a cloud inside the uterus? Or, most horrifyingly, they thought, would it flow in entirely the wrong direction, out into the rest of her body through the fallopian tubes? While standard retrograde menstruation might be nothing to write home about, an entire period’s worth of menstrual fluid going into your body might be something of a different story. What NASA clearly didn’t do was ask a woman what happens to her blood when she’s sleeping. Vigorously exercising. Lying on the floor with her entire lower body propped upside-down against a wall in an attempt to combat cramps (this can’t just be me, right?) They also seemingly didn’t think to ask the Russians, who had already sent women into space quite successfully and quite without and bloody incidents. Because, it turns out, the uterus is pretty good at doing its job, with or without gravity’s help (I’ll refer you back to the aforementioned contractions, which basically serve to expel that shit that like the black vomit from The Exorcist).
Long story short, Sally Ride was fine. And so are you. The idea of your menstrual fluid turning retrograde like a rogue planet trying to screw up your love life might sound really fucking scary, but it honestly isn’t anything to worry about in and of itself. I’d be more worried about Mercury if I were you.
Bella x
Photo by Anna Shvets from Pexels