This is called a decidual cast. It occurs when the lining of a

What is a decidual cast? See photos and learn the cause behind it

Three-dimensional visualization of intrauterine conceptus through the uterine wall by tissue clearing method

Nurse raises awareness for decidual cast after experiencing the 'traumatic' menstrual condition

Fleshy Mass Passed Vaginally by a Young Woman

Interstitial ectopic pregnancy, Radiology Reference Article

This is called a decidual cast. It occurs when the lining of a woman's uterus sheds as one massive solid piece of tissue during her period. : r/MakeMeSuffer

Uterine (decidual) Casts - Don't Forget the Bubbles

What is a Decidual Cast?

What is the function of the uterus lining? - Quora

Nurse raises awareness for decidual cast after experiencing the 'traumatic' menstrual condition