"No one really had any idea what this thing was" ... Allison.

"No one really had any idea what this thing was" ... Allison.

Allison Partridge was in a hospital emergency room, and she had just been told that the fist-size tumour she’d noticed in her abdomen might be cancer. And her mother, Leigh, wasn’t coping well with the news.

“My mum was definitely freaking out a lot more than I was," Allison, then 16, said.

Allison had been suffering from severe and worsening pain in her lower abdomen and tailbone. Her dad had died of brain cancer just two years earlier, so she usually tried to hide or deny her own pain to not scare her mother – or herself. But by now the pain and the giant lump were too obvious to downplay.

It had been a tumultuous lead-up to the hospital visit. On the night of April 4 2011, Allie had been in such extreme pain that her mother had taken her to the ER at Children's Hospital of Philadelphia (CHOP). But the pain was nothing new; ever since starting her period at age 15, she’d had excruciating pain once a month. It was usually so bad that she would spend a day or two in bed.

"I didn't tell my mum at first, but my tailbone really began to hurt," she said. It felt as if something was pushing on her coccyx, and she started taking over-the-counter painkillers to cope with her cramps and back pain. A doctor dismissed the pains as normal.

By March, the pain in her tailbone was constant, and her hip had begun to hurt, too. She saw another doctor and a chiropractor, but nothing helped. During one trip to hospital she was told she simply had a hip injury and constipation. 

But by April she was in agony, and with no appetite, she barely ate. Before her second trip to hospital, Leigh remembers, her daughter spent 48 hours crying in pain and fear. Then she found the lump in her stomach, made even more pronounced by her dramatic and sudden weight loss.

"She was always really thin, but now she looked like a POW," her mother said of her 47kg, 175cm daughter.

Early the next morning, her mother took her back to the ER, where a parade of doctors felt her stomach before deciding she might have cancer.

"No one really had any idea what the thing was," Allison said.  

Thankfully, it only took hours to determine that the mass wasn’t malignant – and an abdominal ultrasound revealed an answer that was both surprising and predictable.

Double trouble

Scans revealed that Allison had been born with a rare condition called a double uterus, or uterus didelphys. It meant that some of her reproductive organs, including her uterus, had been duplicated during the early stages of foetal development. It’s more common in women born with a single kidney – like Allison, who had also been born that way.

In 15 to 30 per cent of uterus didelphys cases, menstrual blood becomes obstructed and can’t drain properly. It turned out that Allison’s "tumour" was indeed made from accumulated blood.

Uterus didelphys is rare; estimates vary widely from one in 2000 to one in 1 million. Some women don’t know they have it because it never causes problems, but others experience unusually bad pain after menstruation begins.

Uterus didelphys can also cause recurrent miscarriages and, in extremely rare cases, fraternal twins who are delivered hours or even days apart.

"Basically she had two half-uteruses and two cervixes," said Samantha Pfeifer, director of the reproductive surgery program at the Hospital of the University of Pennsylvania, who was called in to perform surgery on Allison.

Growing internal pressure had caused blockage and damage in one of Allison’s Fallopian tubes, so it had to be removed. The accumulated blood had also put pressure on other organs, which then pressed on her tailbone. This had caused the worsening pain, diminished appetite and severe constipation.

Doctors drained half a litre of obstructed fluid and removed the tissue that was blocking Allison’s blood flow. They left the double uteri intact; surgery to unite them is rarely performed as it’s unnecessary and risky.

Moving on

So will Allison be able to have children? Dr Pfeifer believes so.

"It may be a little trickier to get pregnant, and she may need a C-section, but she should do fine," she said.

Allison, now almost 19, has no more pain. She has recently finished her first year at university, where she’s studying civil engineering.

After the operation her mother blamed herself. "I'm her mother, I should have thought of this," she told Dr Pfeifer.

"You shouldn't – the doctors should have," she remembers the doctor replying.  

Allison is just eager to put the trauma behind her.

"At college, I appreciate being healthy more than other kids do," she said.

"I think I'm definitely stronger because of everything I've been through.”

Three babies, two uteruses

In 2006, Hannah Kersey, from Devon, England, a woman with uterus didelphys, gave birth to three daughters from two wombs - identical twins Ruby and Tilly were delivered from one womb, while baby Grace was delivered from the other.

Doctors say the chances of this occurring are one in 25 million; while simultaneous pregnancies in two wombs is possible (70 cases have been recorded), the birth of the triplets was a medical first.

* Allison and Leigh's names have been changed.