Doctors in the United Kingdom readying to perform a kidney transplant on a young girl noticed the organ they were preparing to use had an unusual abnormality: Five renal arteries.

Most of the time, the kidney has one renal artery — which supplies blood to the kidney — though it’s not uncommon to have two in some cases.

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Renal arteries form from mesonephric arteries when a baby develops in the womb. Sometimes, if more than one mesonephric arteries are present, multiple renal arteries can form as a result, doctors from Manchester, England, wrote in a report published in the New England Journal of Medicine (NEJM) Thursday.

But three or more in a single kidney is much rarer — and can present complexities during transplants.

“Kidneys with multiple arteries are more technically challenging to transplant and are associated with an increased risk of vascular complications,” they wrote, noting this is especially true for children, who have smaller blood vessels than adults.

As a result, the 9-year-old girl — who suffered from a dysplastic kidney (when the organ does not form correctly in the womb) and chronic kidney disease — was unable to undergo the transplant.

Instead, the rare kidney — which came from a deceased donor — was given to a 35-year-old man who, three years post-op, was “clinically well,” doctors wrote.

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As for the girl, she too received a kidney roughly 18 months after she was initially slated to undergo transplant surgery.

“At the 2-year follow-up, she was also clinically well,” doctors said.