Quantitative serum hCG levels are helpful in evaluating suspected ectopic pregnancy because the classical triad of abdominal pain, delayed menses, and vaginal bleeding occurs in less than 20% of cases. Most ectopic pregnancies produce sufficient amounts of hCG to test positive with urine pregnancy tests. A urine pregnancy test can confirm that a woman is pregnant much faster and cheaper than a serum quantitative hCG. Serum hCG quantitation can then be done to determine if a fetus is large enough to be visualized by ultrasound. Gestational sacs are visible by transvaginal ultrasonography when serum hCG levels equal or exceed 1600 mIU/mL. If the hCG level is this high and no sac is visible in the uterus, ectopic pregnancy is suspected. Quantitation of serum hCG levels in paired specimens drawn 48 hours apart can also be used to help diagnose ectopic pregnancy. Women with uncomplicated pregnancies increase their serum hCG levels at least 1.6 fold during this interval. Smaller increments are consistent with ectopic or complicated pregnancy.. Healthy, non-pregnant women have serum hCG levels < 5 IU/L. Serum hCG values > 25 IU/L indicate pregnancy. Levels between 5 and 25 IU/L often indicate early pregnancy, but results need to be interpreted cautiously because false positive results can occur in this range. In this situation, the test should be repeated 48 hours later to confirm pregnancy. Serum hCG concentrations double every 1.5 . Hcg level chart by week of Gestational Age post LMP in hCG beta subunit IU/L: 2-3 weeks the HCG level is among 10-70 3-4 weeks the HCG level is among 10-750.