Nurse's TikTok Explains 'Decidual Casts' – When Your Uterus Lining Sheds Whole

"It was tissue, about the size of my palm, and it was in the perfect shape of my uterus."
Carol Yepes via Getty Images

Have you ever heard of a decidual cast? The answer for a lot of people will most probably be ‘no’, but if you’re a person who has periods, it’s well worth cluing up on.

A decidual cast is essentially a large piece of tissue that passes through your vaginal canal. And the wildest thing about it? It’s often triangular in shape - an exact replica of your uterus – because a decidual cast is formed when your body decides to expel your entire uterine lining in one piece.

The Google images are equal parts fascinating and horrifying if you’re brave enough to have a peek, so it’s no surprise women are sometimes shocked if it happens to them.

Over on TikTok, a nurse named Madi Swegle has shared her experience of recently passing a decidual cast to raise some much-needed awareness.

“Something extremely scary and honestly a little traumatic happened to me last night. If you’re a woman, this is important,” she says in the clip. “I’ve never heard of this before in my life [and] I’m a nurse.”


Google “decidual cast” at your own discretion 😵💫 Honestly debated if I should share this or not but I wish I had known about this before it happened to me. It was so painful and scary 😩 #psa #decidualcast #periodcramps #period #ladies #menstralcycle #fyi #medicaltiktok #womenshealth #ob #obstetrics #obgyn #nursesoftiktok

♬ original sound - Madi Swegle

Swegle says her period cramps suddenly became “very, very intense”, to the point where she describes them as “the worst pain I’ve experienced in my entire life.”

She sat on the toilet for about an hour, with a bucket in front of her because she felt nauseous from the pain. She says her boyfriend was talking about taking her to the hospital when “something” came out of her.

“At first I thought it was a massive blood clot, but it wasn’t,” she says. “It was tissue, about the size of my palm, and it was in the perfect shape of my uterus.

“The best way I can think to describe it is that if you’ve ever seen or felt a placenta, it felt like that kind of tissue. It was terrifying to see it come out of my body.”

Swegle sent a photo of the tissue to someone she knows who works in obstetrics and gynaecology and also hit up Google. She soon discovered it was a decidual cast.


Replying to @jn0328 PART 2! Answering some questions!

♬ original sound - Madi Swegle

“Instead of shedding your uterine lining over a series of days during your period, it’s when your entire uterine lining comes out in one piece through your cervix,” she explains.

“The cramps I was feeling were really like contractions, and my cervix dialated a little bit to pass this [... ] piece of tissue.”

Numerous medical sites suggest that decidual casts are very rare, but the comments on Swegle’s video are full of women saying this happened to them.

“This happen to me and [I] was like ‘did a fucking tongue come out of me’ very scary, googled it and figured out it was probably a decidual cast and even my OBGYN hadn’t heard of it before,” one person commented.

Another added: “It’s probably ‘rare’ because no one ever comes forward about it. This happened to me once and I thought I was having a miscarriage.”

The good news is that Swegle started feeling much better after passing the tissue, but if you’re concerned about a decidual cast, the advice is to seek medical support.

“Passing a decidual cast does not necessarily indicate an urgent problem, but when a woman passes a cast, she may have a significant amount of discomfort and cramping pain (like pretty bad menstrual cramps),” Dr Karen Duncan, assistant professor in the Department of Obstetrics and Gynaecology at NYU Langone Health, told Bustle.

If you have severe or worsening pain with periods, or pass anything strange looking from your vagina, Dr Duncan recommends seeing your doctor.