Dear Ritu

With AIR 4550 and belonging to UR, sorry to say that the chances are very low for you as the last year's cut off was AIR 1353 for AIIMS Mangalagiri though there can be some hope for you as 6 new AIIMS has been introduced this year and seats have been incremented to 609 for general category (doesn't guarantees you a seat). And according to last year, the total number of vacant seats were 103(56 for UR alone) for which the open round of counselling was done and keep in mind, in 2018, there were no new AIIMS, the mentioned vacant seats were from eight AIIMS(excluding Delhi).
However, the merit list changes every year, only on that basis the admission is done.

Hope this helps you.

All the best.