worried

So I am just about 36 Weeks pregnant. I let my doctor know I had been using percocet 30Mg for a brief period of time. She let me know that if my daughter tests positive at birth, social services will becomw involved. I stoped using at 35 Weeks. No symptoms of withdrawel by the way. I was wondering how likely it is that she test positive in either her blood or urine. I know it will be in meconium. Please explain the answer. I dont completely understand how iy could not be in her system. Again, im wondering specifically about the blood and urine, and would like an explanation. Thank you:)

[Julia M Aharonov, DO]

Opiates get metabolized in baby's blood and urine as both are constantly circulated and exchanged. Meconium gets accumulated slowly in the baby's bowels over the time if the pregnancy as the first time the baby moves its bowels is usually and hopefully after the delivery. Thus everything you take after the 20th week (after the formation of the intestinal tract) will show up in the meconium. I hope this is clearer.