Without any basis of expertise in any aspect of this topic, a sharp, forceful motion seems more likely to cause damage than a slow pressure. Also, if someone genuinely fell on something, they probably didn't do any prep work; whereas a deliberate insertion might involve things like stretching and lubrication (but probably not in this context).

Essentially, the amount of internal damage they need to look for is inversely proportional to the amount of lube you used.

Sure.

Perhaps you were naked in your pottery shop refinishing the teacup using, say, an oscillating sander, and the hot, newly roughened surface of the rim of thd teacup was propelled violently into your anus. What could potentially be observed as contusions in and around your anus should also be investigated and treated for abrasion and burns.

Or, in fact, you were naked, having a magic tea party in the bathroom with what, through conversation it is revealed, were your imaginary friends while you were tripping on research chemicals. The 3rd cup of "tea" you were drinking started to taste like cinnamon as your ass began to feel so incredibly empty. We might need to do a specific tox screen for the party drugs, and the mystery tea you might have found under the bathroom sink. Some of that mystery tea could also have spilled in your ass, by way of the teacup vehicle. The blunt trauma wounds on your anus may be masking chemical burns.

With imagination, developed from observing human behavior, it is relatively easy to appreciate the benefit of medical staff asking questions and getting answers.