Where can I buy a GBS test?

[Fissawissa]

My sister & Aunty both tested positive for GBS. I asked my MW yesterday for the test & she said I have to buy it privately online.
Can anyone tell me where the best place to buy it please?

www.groupbstreptest.co.uk
The test is free to order, and is 35 pounds to process.

Gbs can disappear during the pregnancy, or just appear near the end, I have had it picked up in urine samples near the end, so if you buy a test and its negative it doesn't mean you won't have it by the time you give birth.

When is the best time to take it, considering the turn around time?