Have you ever wondered how long it takes for a little yellow Lego head to pass through the human body? No, us neither but an international team of pediatricians decided to find out anyway.

The answer: an average of 1.71 days.

In the name of science, six healthcare professionals volunteered to swallow a Lego head and spend the next few days sifting through their bowel movements to retrieve the evidence. To meet the grade for participation, the volunteers must not have had gastrointestinal surgery and must be able to show an ability to swallow such an object – but, perhaps most importantly of all, they should not have a problem rummaging through their own poop.

The results have been published in the Journal of Paediatrics and Child Health in an article titled “Everything is awesome: Don’t forget the Lego”. A reference, in case you haven’t seen the film, to the song “Everything Is AWESOME!!!” as well as the pediatricians’ blog Don’t Forget the Bubbles.

To account for any individual differences, pre-ingestion bowel habits were standardized by an appropriately named scale, the Stool Hardness and Transit (or SHAT) score. The amount of time it took to travel from mouth to toilet was also aptly titled – the Found and Retrieved Time (aka the FART) score.

So, what did they find? It took an average of 1.71 days for the Lego head to exit the body, with a varied FART score between 1.14 and 3.04 days. The researchers also note that “females may be more accomplished at searching through their stools than males”, adding this “could not be statistically validated”. Presumably, this is referring to the fact that one male volunteer never found a Lego head. (Let’s just hope it made it out ok.)

Although extremely tongue in cheek, there is a point to this research. The team hope parents can now rest safe in the knowledge that their kids’ extra-mealtime habits will likely not cause any nasty health complications.

"It is possible that childhood bowel transit time is fundamentally different from adult, but there is little evidence to support this, and if anything, it is likely that objects would pass faster in a more immature gut," the study authors wrote. "This will be of use to anxious parents who may worry that transit times may be prolonged and potentially painful for their children."

And if a Lego head or similar object does go mysteriously AWOL, the pediatricians' advice to parents is not to go looking for it. 

"If an experienced clinician with a PhD is unable to adequately find objects in their own stool, it seems clear that we should not be expecting parents to do so – the authors feel that national guidance could include this advice."