Medical students in Oregon made the discovery only after the death of Rose Marie Bentley

Rose Marie Bentley was an avid swimmer, raised five children, helped her husband run a feed store and lived to 99. It was only after she died that medical students discovered that all her internal organs, except for her heart, were in the wrong place.

The discovery of the rare condition, which was presented this week to a conference of anatomists, was astounding — especially because Bentley had lived so long. People with the condition known as situs inversus with levocardia often have life-threatening cardiac ailments and other abnormalities, according to Oregon Health & Science University (OHSU).

The finding was made when the class of Cameron Walker, an assistant professor of anatomy at the university in Portland, was examining the heart of a cadaver last year. They noticed the blood vessels were different. When they opened the abdominal cavity, they saw that all the other organs were on the wrong side. The unusual blood vessels helped the heart compensate.

Walker described his reaction to the find as “definitely a mix of curiosity, fascination and a sense of wanting to explore a little bit of a medical mystery — a medical marvel really — that was in front of us”.

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When he researched the life expectancy of people with the condition, he found no documented cases in which a person lived beyond age 73.

Bentley’s family had not known about the condition, which OHSU says occurs only once in every 22,000 births. Apparently Bentley herself didn’t either.

Bentley, who lived in Molalla, 25 miles (40km) south of Portland, had led a normal life. Her only recurrent physical complaint was arthritis, her daughter Louise Allee remembered.

But there were signs. When Bentley was in her 50s, she had a hysterectomy, and the doctor also wanted to remove the appendix. But he couldn’t find it, Allee said.

When Bentley had her gallbladder removed about a decade later, it was on the opposite side of where it should have been, she said. “No one said a thing,” Allee said. “I was surprised. This was before they did it with a scope, and she had a good-sized incision. You’d think they would have said something, but they didn’t.”

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Bentley had agreed to donate her body to OHSU, Oregon’s only academic health center.

Walker said: “This is an important case that really gave us an opportunity to talk about the importance of future clinicians paying attention to subtle anatomic variations, not just large anatomic variations, in terms of addressing their future patients as individuals.

“Don’t judge a book by its cover, and always check and see what you’ve got before you talk about care.”

Allee said her mother would have been delighted that the donation of her body led to a learning experience. “She would have been tickled to know she could educate with something unusual,” Allee said. “Dad [James, who died 15 years ago] would have loved to know about it so he could tease her.”