Thanks for the query.
Usually blood test
gives accurate result compared with urine test for pregnancy
Sometimes urine pregnancy test kit can give false positive results.
So generally we have to consider the blood test.
For more details : http://srsree.blogspot.com/2012/05/pregnancy-tests.html
But rarely blood test can also give false negative results because of wrong dates etc.
So if you want to be sure, wait for one more week.
And if you do not get periods even after one week repeat the blood test.
If the test comes negative, the possibility of pregnancy is very less.
And yes, poly cystic ovary disease can recur.
It can occur because of hormonal
So, if you do not get periods after one week and if the test comes negative, consult gynecologist once and go for ultrasound
This can help in finding out the status of poly cystic ovaries.