It is rare but it occurs to only a very few people. I suppose, the polyethylene glycol-containing lubricating gel used for transvaginal ultrasound may be responsible for the condition. Talk to an immunologist.

OMiGosh-- it would NEVER have occurred to me that this was a risk to contain aloe.  WOw.   

Some gels bother me.  I stopped a tech once from using one with aloe vera.   That would have been SO HORRIBLE.  I sometimes break out in a rash.  It depends on the preservatives used.  I wouldn't allow a transvag gel with parabens like the one mentioned.  I know what happens when paraben-preserved lube goes inside me.  It's not pretty.    

Nobody used to believe me that I was allergic to ultrasound gel. Thankfully for me, I only get a terrible rash.