The levels are higher in a multiple pregnancy; and if the levels don't double as expected, this suggests that the pregnancy is unhealthy. Possibilities include a non-viable intrauterine pregnancy which will miscarry; or an ectopic pregnancy. If the beta HCG level is more than 1000 mIU/ml, and the doctor cannot see a pregnancy sac in the uterine cavity on vaginal ultrasound scan, then it's possible you have an ectopic pregnancy. Beta HCG levels can be measured in the blood by RIA (radioimmunoassay) , CLIA (chemiluminescent assay) and DELFIA ( fluorescent immunoassay) testing; and positive levels (more than 10 mIU/ml) in the blood can be detected as early as 2 days before the period is missed. In the old days, the only way of determining the presence of HCG was by testing the urine, i. e, by using urine pregnancy test kits. Modern urine pregnancy kits (using monoclonal antibody technology ) are now quite sensitive and can detect a pregnancy as early as 1 to 2 days after missing a period (at a blood HCG level of about 50 to 100 mIU/ml). The benefit of urine pregnancy test kits is that they are less expensive; and testing can be done at home by the patient herself. However, instructions need to be followed carefully, and errors in interpreting the test results are not uncommon. These errors could occur if the urine is too dilute; or if the test is not done properly; or if there is a urinary tract infection exists.. Most clinics start testing beta HCG levels about 14 - 16 days after egg collection; and repeat the test every 48-72 hours. As the embryo grows rapidly, HCG levels normally double every 2 to 3 days. Thus, one reliable sign of a healthy pregnancy is the fact that the HCG levels are increasing rapidly, and often doctors will measure serial beta HCG levels 3 days apart in order to determine the . Methods. Patients undergoing in vitrofertilization (IVF) and ET were monitored by serum quantitative hCG levels 14 days after ET. If positive, serial values of hCG were obtained and transvaginal ultrasound was performed 3 weeks after ET and weekly until fetal cardiac activity was seen..