Usually, it's not exactly baffling how the objects got up there. But just occasionally, there is a real mystery. Recently, for example, a team conducted a colonoscopy on a 63-year-old man and found a fly lurking in his colon.
The man, who had an unremarkable history of minor heart problems, asthma, and tinnitus, showed up for his colonoscopy having prepared his bowels for the procedure. Not having a view clear of debris is detrimental to the usefulness of a colonoscopy in diagnosis, and as such medical professionals have come up with a scale of cleanliness known as the Boston Bowel Preparation Scale.
Just as you can have your erections graded (when medically necessary) you can have your colon cleanliness assessed on a scale from 0 to 9. The right colon, transverse colon, and left colon are assessed on a scale from 0 ("mucosa is not visible due to solid feces, and the fecal masses cannot be removed") to 3 ("the entire mucosa of the colon segment can be seen well, with no residual soiling"). These scores are then added up for the overall score, with the patient in question scoring 2 ("the mucosa of the colon segment can be seen well, with minor amounts of residual stool, small fragments of stool and/or opaque liquid") in all segments for a good overall score of 6.
With a clear view, as well as moderate pancolonic diverticulosis, five colon polyps, and hemorrhoids, the team found a fly hanging out in the transverse colon. The fly was not moving, even when prodded by the doctor performing the colonoscopy.
"The patient was unsure on how the fly got into his colon," the team explained in his case report, adding that the find was very rare and a mystery. "He had strictly consumed clear liquids the day before the procedure. He reported having eaten pizza and lettuce for the evening meal 2 days before the procedure, but does not recall a fly in his food."
And yet here the fly was, seemingly completely intact after its ordeal and subsequent death.
The study is published in The American Journal of Gastroenterology.