Is this child an older toddler? Tall and thin? Sometimes when they are tall providers don't lift them high enough to see the top of the buttocks/lower back area. It feels like you are shoving their shoes into their faces because of those long legs.
Once they are laid on the clean diaper to close, the chances of seeing are low due to how high the diaper goes up their backs. Back when I was training, this was a common occurrence with new hires, especially in children with darker skin.
I always taught them to roll the legs to each side after wiping, but before placing the new diaper and check the lower back/spine.
Using a thin coat of skin protectant every other change will cut down on the chances of it, too.
If you are already doing that, I would suspect the same as Kendallina. Watery flatulence on the ride home. Maybe DCM is a tailgater/hard braker and the kid is hitting his air brakes all the way home??
