Medical Student here.
On my OB/GYN rotation we had a lady well into her 70's come in with difficulty pooping. Abdominal CT scan in the ER showed a mass in her abdomen/pelvis that, as best we could tell, was her uterus. A lady's uterus at that age is usually the size of a lemon. This one was the size of a basketball. It was so big that it was occluding her colon and subsequently her ability to poop.
The first step was for us to figure out what was causing the mass. Problem is, the patient was mentally handicapped and noncommunicative. She had been jumping from caretaker to caretaker and no one really knew her history. She resisted attempts to undergo a pelvic exam (read: look up her vagina and see what's what), so the decision was made to take her to the operating room and figure this whole debacle out during an "exam under anesthesia".
I'm scrubbed in on the case. The resident looks over at me, gives me a nod, and says "well, figure it out." I lube up and begin with a bimanual exam. That's the OB/GYN exam where the fingers of one hand are in the vagina, and the fingers of the other hand press on the abdominal wall and you try to palpate structures between your hands. But, I didn't get very far. As soon as I put the fingers of my right hand into her vagina I knew what was up. All I could say was "Oh dear God." I stayed quiet and gestured for the resident to do the same exam. She got just as far as I did and was like "Oh no way." She then gestured to the attending physician who was now gowned and gloved and ready, and in turn, he had a similar response to the bimanual.
Here's what was up. Her vagina ended abruptly after a few centimeters. It was just a wall. Imagine it being about the diameter and depth of a shot glass. It's called a vaginal septum, and it's a rare abnormality in which the vagina doesn't develop into a hollow structure as it should, and instead has a blockage. Imagine the vagina as a toilet paper tube, and this septum being a permanent door damming it up in the middle.
The implications are what made us all pause. This means that this old woman has been having periods her whole life, but they've had nowhere to go. No outflow tract. Just... bottled up in her uterus. This wasn't a mass per se, it was a uterus inflated with EVERY PERIOD SHE HAS EVER HAD.
The resident handed me the scalpel and took a step back. I had no idea what monsters might have been lurking in Pandora's Box. (No, the patient's name was not Pandora). I made a small incision in the septum and waited for a thousand evils to pour out of that thing a la the (spoiler alert) recent Demon Queef on Game of Thrones. What emerged escapes explanation, but suffice it to say, Hershey's chocolate syrup has been ruined for me, and 3 liters of it at that. Brown and Red and Clotty and Smelly and Awful.
After we drained her uterus, we resected the rest of the vaginal septum and that was that. Problem solved for her. Cannot unsee for me.