Parents go to great lengths to ensure that their toddlers do not swallow coins, batteries, toys, pebbles, insects and other choking objects that pollute a child's world. But it is inevitable that children will swallow things. So a group of healthcare professionals decided to find out how long Lego stayed in the human body by experimenting on itself.

CNET's Amanda Kooser reports that doctors affiliated with the medical blog Don't Forget the Bubbles knew there was a lot of data on swallowing coins, the foreign object most commonly swallowed by children, which lasts about two weeks. But data on how long it takes for a plastic toy to work its way through the body is scarce. So they recruited subjects with no history of intestinal surgery to swallow the plastic head of a Lego figure. They then examined their poop to see how long it took for the decapitated Lego head to come out.

Bruce Y. Lee of Forbes reports that each participant kept a stool log for three days, rating his or her bowel movements using a Stool Hardness and Transit (SHAT) score. A person with a higher SHAT score had looser and more frequent bowel movements, meaning the smiling piece of plastic could pass through more quickly.

After swallowing the Lego noggin, each participant was responsible for analyzing their own poop to locate the object. According to the blog, “[a] variety of techniques were tried – using a bag and crush, tongue depressors and gloves, chopsticks – no turd was left unturned.”

After retrieving the Lego head, participants calculated their Found and Retrieved Time (FART) score, or the number of days it took to pass the Lego. The research appears in The Journal of Paediatrics and Child Health.

It turns out that for most participants, it took an average of 1.71 days for the Lego heads to travel through the digestive tract. There was also no clear correlation between the SHAT and FART scores. But there was one disturbing result: for one unfortunate subject, the Lego head never appeared again.

“Maybe one day, many years from now, a gastroenterologist performing a colonoscopy will have it stared back at him,” the team wrote on their blog.

The result of the study is that, at least for adults, the toy object seemed to pass through without complications. But as they write on their blog, the team cautions that the study was really just a bit of pre-holiday fun and doesn't apply to children who swallow bits of toys. The sample size was also small, making the study of questionable value even for the adult population. (Stepping onto a Lego is a different story, though.)

Still, it's probably best to avoid ingesting Legos or toys of any kind whenever possible and schedule a colonoscopy after age 45 to ensure everything stays great.