Question about personal statement: Should I explain bad grades?

I did not do so well for about 2 semesters of my undergrad due to a very personal medical reason that my doctor told me not to put on my personal statement. Would it be ok if I did not explain the bad semesters and just try to improve for my last year? Or should I ignore what the doctor said- I was diagnosed with clinical depression and she told me that I would not know the outcome from doing that, like what the reviewers attitudes would be for a situation like that.