Leucocyte: +++

I’m 28 weeks and I went in for a check up and growth scan and they said something was in my wee sample and that they need to send it off for tests but didn’t say what it was, so when I came out of my appointment I logged into my only pregnancy notes and it says Leucocyte: +++ I have never had this in any of my other 2 pregnancies can anyone help me and give me any advice what Leucocyte: +++ means and is it serious?