The best reading will come from her anus

"Betty this new device is best suited for anal readings. I know it will be uncomfortable but I'd really like to try it out"
Betty nodded her head in agreement, "Well alright Dr. Rossin, I'll trust you to be gentle on my tushy"
The busty blonde stood up, her tits jiggled and bounced as she turned around and bent over the chair she had just been sitting on. Her skirt and panties were still on so she slid them off over her sexy hips and well formed ass. Her young butt was up in the air, waiting to be violated and she knew it.
Dr. Rossin got a sudden rush of worry as he stood and looked down at her heart shaped behind,
"Now Betty you promise not to turn and look right? This is a very experimental piece of equipment and I'm not allowed to show it to anyone"
"Of course Dr. Rossin! I swear I won't turn around."
Dr Rossin smiled "Good girl" and slowly unzipped his pants, exposing the rock hard cock he'd been hiding from her. With one hand on the small of her back and the other on his raging manhood he slowly guided it towards Betty's puckered little hole. Reaching towards the table beside him he grabbed some Vaseline and applied it to his cock just before pushing against her asshole.
Betty closed her eyes tightly as it penetrated her. She didn't expect a medical device designed to enter the anus to be so large. It felt wet and warm as it pushed further into her and she couldn't help but think how much it would help the pain if she could just play with her clit. Finally it seemed that the device was all the way in and she spread her legs a little more to accommodate.
Very slowly she felt it being pulled out and she breathed a sigh of relief but just before it was out it was pushed back in even more quickly! The device just kept up the pace, pushing in and out of her.
"Dr Rossin, are you supposed to be pushing it in and out like that?"
He replied almost breathlessly "uuhh Yes Betty, study's show it helps the woman relax so we can get the best reading. Don't worry it's almost done and it'll send a warm gooey liquid into your anus to help you feel better"
"Ok then doctor, let me help you with that" Betty said as she started to push her own body back and forth on the device.
Dr. Rossin stood still and watched Betty slowly fuck his cock with her little ass. She looked so incredible backing up on it like that. Suddenly he felt cum rushing into his cock and had to hold back from screaming out as he exploded into her ass.
Betty moaned as cum dripped out of her and she pulled back on the device letting it slip out. Dr Rossin quickly put it back in his pants and zipped up before Betty turned around.
"Well that was some device Dr. Rossin! It may be a little too big for some women though"
Dr. Rossin wiped off his brow, "Well I'll be sure to pass along your comment to the developers Betty. Now go on and get dressed you'll start work tomorrow young lady!"
Betty smiled with happiness and did a little jump which made her big tits bounce and a small amount of cum to fall to the floor. She got dressed and walked out his door leaving her bra on the table.