itchy feet - chances of cholestasis / high bile salt levels?

SB
Hi everyone - I'm currently 38 weeks and have been experiencing very itchy feet (especially at night). I went to the doctors today and they wanted to test for cholestasis. Given that I'm already 38 weeks, they said if the bile salt test comes back slightly positive tomorrow, they'll go ahead and induce (the liver function test takes a full week to come back). Or maybe it's the other way around!
I know cholestasis is quite rare but I'm wondering what are the odds of bile salt tests coming back positive? I'm ok with early induction if best for the baby but also nervous...