If you're like most people, the idea of having an unborn twin growing inside you for the past four decades sounds like the stuff of horror movies, but for Jenny Kavanagh, it was a harsh and terrifying reality. After visiting a doctor upon experiencing heavy periods, the 45-year-old former Londoner was worried that her implanted contraceptive coil was causing the issue. Never in her wildest dreams could she have imagined what was to come next.

Her doctors, who insisted she have an ultrasound, discovered that Kavanagh had a 10-centimeter mass growing on her left ovary. They told her to have surgery immediately, worring that the mass may rupture and kill her. But when they finally opened her up and got a closer look, they discovered the mass had a face, an eye, a tooth, and long black hair similar to Kavanagh's.

The mass was her unborn twin.

“I try not to think of it too much because I don’t want to feel sad about it,” she told Mirror Online. “But I try not to feel sad about it. I try to remember that it had no heart and no brain. And that it would have almost certainly killed me if they hadn’t found it and removed it.”

The Twickenham native admits that she was never one to see doctors regularly; she would avoid the visits unless absolutely necessary, and had never seen a gynecologist up until that point. The mother of two says that despite her infrequent doctor trips and the unknown mass, both of her pregnancies were normal.

Kavanagh moved to Cyprus with her second husband in 2005 to escape the “rat-race” of London, but it wasn’t until recently that she started to feel the effects of the mass. Cyprus doctors then found the mass in May, taking Kavanagh into surgery 11 days later for a three-hour operation. Kavanagh requested that doctors photograph the mass, which they showed her after the surgery. She was shocked to see the obvious face, and the hair that matched her own.

“The whole thing was so surreal, I think I needed to see them to get my head around it all,” she said.

Doctors told her that the mass of cells, most likely stem cells, had been inside her since birth. Though they cannot say for sure, they believe it is likely that Kavanagh presented a case of fetus in fetu, which Radiology Reference describes as an extremely rare abnormality that occurs when a non-viable fetus becomes enveloped within the developing fetus.

“The fact that it had long black hair — just like mine — a face with one eye, and one baby tooth makes it more believable,” she said. “It’s difficult to describe how I felt when I saw it. I felt shocked, very scared, horrified, and it felt like an alien was inside me.”

Doctors also told Kavanagh that her case was akin to an ectopic pregnancy, and that her ovary protected it, allowing it to grow. However, as it got bigger, there was more of a chance of hemorrhaging.

Now that Kavanagh has undergone the surgery, she says she feels lucky to be alive, but still feels sad for the sister or brother that could have been. “When I showed the picture to my mum she was really sad — saw it as her unborn child, and my unborn twin.”

She is now trying to live her life as normally as possible after such a traumatizing event.