Do you mean the sister in law thinks that the PCOS is because of the coil? And that it is an infection of the ovaries? Because that isn't true. Unless your sister is using the hormone plus one (it's known as Mirena in the market) the coil isn't going to affect her hormones at all. In fact the Mirena one would make her PCOS symptoms better. And PCOS is all about hormonal imbalance and is not an infection at all.