best wishes for a safe procedure. it may depend on how shes feeling. she may prefer to rest in her crate..I would call it when she gets home....most use the onesie with no issues.....   
when i was nervous I just double checked with my vet and he assured me of the meds he would use and also the dosage (anesthesia), they weigh them that very morning as to be sure the are administering the correct dosage. Ask as many questions as you need to. Also you might want check on best options if you find she is bond up after the surgery.  
That does happens sometimes and with keylo we did warm baths and mineral oil.....just a heads up your Missy may not experience but we did so I thought I would add that.    
We are here for moral support and best wishes to your Missy and welcome to yt!!     
				__________________  Cedric N Lola N Keylo    RIP Punkee Princess        |