This young patient had an unremarkable history and no medical symptoms, but closer examination revealed an anal canal duplication.

Writing in BMJ Case Reports, the girl’s doctors did not give her precise age but noted that the anomaly had gone unnoticed until her mother had spotted it when her daughter did a handstand — so she was not an infant.

And while it might seem surprising that the second perineal opening went unnoticed for so long, the doctors said anal canal duplication could remain undiagnosed until adulthood, as “the anomaly may go unnoticed during routine examinations”.

They said it was one of the rarest congenital gastrointestinal anomalies.