Detection of the hormone in the blood is ahead of the results of pharmacy tests. Most of them are designed for hCG content in urine of 20-25 units per 1 ml. This usually corresponds to the first week of a missed period. The timing of pregnancy detection in the laboratory is possible 5-8 days from conception. However, blood tests are much less likely to show incorrect results.
If you need to accurately establish conception and whether the fertilized egg is attached normally, then 2 studies are needed with an interval of three days. It is important to take them in the same laboratory.