Seeking explanation of WWII Separation Codes

I have a WD AGO 53-98 (Military Record and Report of Separation Certificate of Service) for Amelia I Waara N 771 740 1st Lt. Can someone please help me decipher the codes in Box 33 (Reason and Authority for Separation)? They read as follows: Reld AD WD Cir 290 Sec II 22 Sep 45 P 22 S0 251 Gardner General Hospital 27 Nov 45. I am told there may be a difference in codes for officers and enlisted...? I understand that 22 Sep 45 and 27 Nov 45 are dates, but not sure what they signify. (Her dates of service were 23 March 1943 to 3 March 46.) I presume that Gardner General Hospital is where she worked.  Thank you!