Actually, what you said is not true. Check out my comment under 65. I don't feel like typing it all again.

119 - As I said, you shouldn't be up in everyone's faces when you clearly aren't too clued up on this subject. Beta HCG can be measured in the blood and urine, usually it is positive in urine when one is pregnant, but, when this is in question, pregnancy can be CONFIRMED by a serum beta hcg. Beta hcg levels are also helpful in the diagnosis of gestational trophoblastic disease (embryonic tumours), ectopic pregnancies, and retained products of conception after miscarriage, as well as being a part of the triple test for congenital abnormalities, carried out in the first trimester. It is uncommon and a bit retarded to use beta hcg levels to determine gestation, as their is such a huge variance between pregnancies, and it is so much easier to rely on history, abdominal examination, and ultrasound. What probably happened in your case, is that your serum beta hcg was positive, and they used either your menstrual dates or the size of your uterus to tell you you were at 19 weeks.

We actually usually do determine dates from early ultrasounds, either correlated with menstrual dates, or, alone, if the mom is unsure of her dates, was using non-barrier contraception, or had irregular periods. And, not to be finicky, but the official rule is: first day of last NORMAL menstrual period, plus 9 months, plus a week.

That's not how it works, you measure the uterus physically at each visit, and, if the trend isn't stable, you do an ultrasound to assess for evidence of intrauterine growth restriction and placental insufficiency, if this is the case, you need to determine the cause for this. Beta HCG isn't helpful in this instance.

I agree! Some people are almost impossible to get venous blood from, and, even though I have been taking blood for 5 years, I still find that I have bad blood/drip days :(