Hi DadThal,
Welcome on the forum,i am really sorry to hear about your situation,i wish and pray that your baby will be healthy.
I went through this test myself before my second baby was born,it's done here in karachi in couple of hospitals,one is AGA KHAN HOSPITAL,and other is PNS Shifa,a navy controlled hospital,as Narendra gave you the information,a needle is inserted in mother's abdomen to take out the sample,it's not VERY painful,and patient won't feel a thing if given local anesthesia,after the test patient is advised to be on bed rest atleast for three days to avoid misscarriage,and given painkillers for any kind of pain.
The test was done when i was about 11-12 weeks pragnant.
Hope this helps,feel free to ask any questions.
ZAINI.