Dripping urine on pant during sneezing

I have a problem that I think most of the women have. During sneezing due to force of sneeze some drops of urine came out on the pants. When I am at home then I change my pants for offer salat but when I am in university it does not possible to change there clothes and in doubt that my clothes are dirty with urine I can't offer my prayers. Is the pants become dirty due to this biological reason? Can I offer my prayers with that pants or not?