Early Pregnancy Concerns: Blighted Ovum History & Positive Tests

Question
I am 32 years old and this is my second pregnancy.  I miscarried my first baby just last August (blighted ovum).  My last menstrual period was 11/9/05.  I took 2 HPT the first week of December and they both turned positive.  I took another test the week of Christmas to be sure before my husband and I tell our parents.  That too was positive.  I had my dr.'s appointment yesterday wherein I should be 8 weeks preganant if you base it on my last period.  The NP did a finger test and said I feel pregnant.  Nevertheless, I asked for an ultrasound to make sure I didn't have another blighted ovum.  Another person (I think an MD but not my regular dr.) did an ultrasound but didn't see anything.  They ordered a blood test to see what's going on.  I heard from the office today and they said I need to come back tomorrow because the blood test came out boderline.  How could this be?  What does that mean?

Answer
If your last period started on November 9, you probably ovulated around November 22 and could have conceived if you had sex on November 21,22,23, or 24. If you had a positive pregnancy test, you are definitely pregnant. You are now 8 weeks 1 day pregnant (from your LMP). After 6 weeks gestational age, a sonogram usually shows a fetus, a gestational sac, and a fetal heartbeat. If the blood test (HCG) is dropping, and there is nothing seen on ultrasound, you may have miscarried, or they may merely have missed the fetus on ultrasound. I would suggest taking two blood tests for pregnancy (Beta HCG) 48 hours apart. If there is a doubling of the results in 48 hours, it indicates a viable pregnancy. If there is a halving of the results in 48 hours, it indicates a miscarriage. If both tests have a value of less than 5, you were never pregnant. The urine tests you took may have been incorrect or inaccurate. The best time to take a pregnancy test is seven days after missing your next period. If yur period started on November 9, the best time to take a pregnancy test was any time after December 13.