What is a decidual cast? Why this labor nurse is sharing her painful menstrual experience

What is a decidual cast? A woman in a sleeveless white top clutches her midriff in apparent pain.
What is a decidual cast? Experts share what you need to know about this menstrual condition. (Photo: Getty Images)

A labor delivery nurse’s TikTok about her rare menstrual experience is going viral.

Madi Swegle, who lives in in Iowa, took to the video sharing platform on Nov. 23 with a PSA. She said that her period had begun the day before and that while it started off as a normal cycle, she began feeling intense cramping come dinnertime. Swegle sat on the toilet with a heating pad, hoping that the cramps would pass. Instead, after an hour of the “most intense pain” she says she has ever felt in her life — which came with chills and nausea — something else happened.

“At first I thought it was a massive blood clot, but it wasn’t,” Swegle said in the video. “It was tissue about the size of my palm, and it was in the perfect shape of my uterus. The best way I can describe it is if you’ve ever seen or felt a placenta, it felt like that kind of tissue. It was terrifying to see that come out of my body.”

After Swegle passed the tissue, her cramps “completely went away.” It was only after she texted a photo of the tissue to a doctor that she learned what it was: a decidual cast.

Dr. Jessica Kingston, clinical professor ob-gyn at UC San Diego Health, tells Yahoo Life that a decidual cast is “a layer of tissue that is shed from the endometrium — lining of the uterus — all at once.” It’s not very common to shed the entire lining at once, she notes, as it’s much more likely for the decidual lining to be shed in fragments throughout the course of one’s menstrual period.

Although passing a decidual cast can be painful, Kingston says it’s typically not a medical emergency.

“It is not necessary to seek medical attention unless the person is also having abnormally heavy bleeding, which means soaking through the equivalent of a maxi pad in less than an hour over the course of two hours, or if the person has a positive pregnancy test,” Kingston says. “Passing the decidual cast is not necessarily a sign of a serious health condition. The only exception is if it is associated with an ectopic pregnancy, or no pregnancy inside the uterus, that hasn't been diagnosed and treated.” An ectopic pregnancy is a condition in which a fertilized egg implants itself somewhere outside the uterus, such as in the fallopian tubes.

While it’s unclear what exactly caused Swegle’s situation, she tells Yahoo Life that her doctor theorizes it may have been caused by the birth control she was taking prior to beginning her IVF journey, which affected her progesterone levels.

Before starting IVF, Swegle was put on oral contraceptives for a month "to control and 'reset' your cycle," she says. "So I was on birth control for a month, stopped it and then the decidual cast happened."

Dr. Sam Rahman, an ob-gyn and founder of the Center for Gynecology and Cosmetics, notes that decidual casts are “most common in pregnant women between the ages of 20 and 40, who have experienced an ectopic pregnancy.” However, she says there are cases in nonpregnant individuals as well.

“While there is no clear reason why someone might experience a decidual cast, potential causes include the use of hormonal contraceptives, particularly those with a high progesterone content,” Rahman explains. “Oral contraceptives, injectables and implants are all possible options.”

After what Swegle went through, she believed it was important to spread awareness about decidual casts, especially after people reached out to her on TikTok saying they were told they had experienced a pregnancy loss.

“I was a little nervous to post the video on the internet in the first place, thinking people would see it as too personal, too weird, too taboo,” she says. “But it's gotten so much support and so many women coming out saying, ‘Oh, this happened to me like 10 years ago — and they just told me it was a miscarriage.’ Or, ‘This happened to me 10 years ago, and I thought I was just being a baby, and my doctor totally dismissed me.’ So I think it's just really made it really clear to me that women need to advocate for themselves — and if something feels off, to advocate for yourself and know that you know your body better than anyone.”

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