Guinness World Records says its guidelines for the fastest marathon in a nurse's uniform are "long overdue a review".
It comes after it refused to consider a nurse's record attempt because she was wearing scrubs instead of a dress.
Officials told Jessica Anderson that its criteria for a nurse uniform also involved a pinafore and cap, but tights were optional.
She ran the London Marathon knowing that her time would not count.
She finished the race 22 seconds faster than the current record holder and described the rules as "sexist" and "outdated".
Jess is a senior sister at the Royal London Hospital.
Her work in an acute medical admissions ward is fast-paced and she wears scrubs to work every day.
So when she decided to challenge the title for the fastest woman to run a marathon in a nurse uniform, she sent Guinness World Records a photo.
She was told that her actual uniform did not meet its criteria for a nurse's uniform.
She went ahead and ran anyway, completing the course in three hours, eight minutes and 54 seconds.
That was fast enough to beat the record.
Jess believes the rules about wearing a dress apply to anyone wanting to challenge the record title - including men.
"Some of the male nurses I work with are really hopeful that they do change the definition," she said.
'I've never worn a dress'
The story prompted nurses to tweet selfies of themselves, with very few dresses on show.
Some pointed out that certain roles don't require any kind of uniform.
This is my colleague @AfsanaB35 and I. We are both RNC’s and SCPHN’s. Our roles are Public Health Advisor School Nurses, we work in the community.... we don’t wear uniforms... Not all nurses wear ‘dresses’! #schoolnurses #WhatNursesWear pic.twitter.com/AeFRp1QcWr— Shal Henry-Treloar (@SchoolNurse2007) May 4, 2019
And male nurses argued that dresses aren't really their thing.
Even the most senior nurse in England got involved.
@GWR I’m in uniform with 2 #futurenurses we are dressed in uniform a bit like @Janderzzz who ran the London marathon... this is what RNs look like.. please reconsider your position pic.twitter.com/jIXVFx0PAA— Ruth May (@RMayNurseDir) May 4, 2019
Guinness World Records has now responded, agreeing it is time for a review.
In a statement, it said that "inclusiveness and respect" were values it holds "extremely dear".
It continued: "While we always need to ensure we can differentiate between categories, it is quite clear that this record title and associated guidelines is long overdue a review, which we will conduct as a priority in the coming days."
It is not yet clear if this could mean that Jess will be awarded the record, or if the criteria will only change for future attempts.
She says it would be "perfect" if Guinness World Records finds a way to give her the title.
But she said it was most important that officials modernise the guidelines.
"I would be quite happy if they changed it in the future or acknowledged that it's sexist and it's not really how we want the profession to be represented."
If she doesn't get the title though, she said she was very tempted to try again next year.