Kim's younger sister Khloe, 26, accompanied her to the medical centre and posted a picture of the scan on her website.
She wrote: "Hey dolls. The PROOF is in the X-ray. Kim's ass is 100% real!!!"
Kim, 30, later Tweeted: "Haha! The things my sisters have me do! Proof baby! RT @KhloeKardashian: Kim got a butt X-Ray... bit.ly/ldeCQZ See, it's REAL!!! LOL."
She was recently forced to deny she'd gone under the knife to boost the size of her posterior.
Talking to ABC Nightline, she said: "Those are just rumours, I don't think I'll ever outlive them.
"For the record, no butt implants. No butt injections, no anything to my butt."
Brushing aside rumors of a fake butt, Kim Kardashian went on to prove that her famous, big ass (the reason for this blog.he he he ) is real. No more butt implant talks, or butt injection talk here, Kim Karashian wrote on her blog that her big butt is all flesh and all real. Yummy...erection time..