Pregnancy tests can be performed both in blood or in urine.The main principle of both tests are, detecting hbHCG (Human Beta Chorionic Gonadothropine) hormone, which shows up in the blood of pregnant women, after the fertilized egg is planted on the uterus wall.
Urine pregnancy test: bhCG hormone is detected in the blood of pregnant woman as early as 6-10 days after the implantation of the fertilized egg but its presence in urine needs a longer time because bHCG reaches the bladder as the blood is filtered through the kidneys. This period will probably be approximately 10-12 days depending on the sensitiviy of the test material. To avoid false negative results, the tst should be repeated in 1-2 weeks after the expected menstrual bleeding.
Blood Pregnancy Test: The hormone can be detected in the blood 6-10 days after the implantation of the fertilized egg .This will be the ovulatuary phase of the menstrual cycle.
Today, In Vitro Fertilization techniques are increasing pregnancy rates and the pregnancy tests should be done on the day which is reccomended by the doctor. This is usually on 7-10 days after the transfer, but the test should be repeated in 2-7 days because bHCG is expected to increase by 2 folds each 72 hours in healthy pregnancies.
As the pregnancy is confirmed the bHCG hormone starts tor ise to its peak until the end of the first trimester and drops to lowest levels towards the end of the pregnancy.
BLOOD bHCG LEVELS AT THE PROGRESSING WEEKS OF THE PREGNANCY
IU/L
3 rd week
60-70
4 th week
10-750
5th week
200-7100
6 th week
160-32000
7 th week
3700-160000
8 th week
32000-150000
1stTRIMESTER
9 th week
64000-150000
10 th week
47000-190000
12 th week
28000-210000
14 th week
14000-63000
15 th week
12000-71000
16 th week
9000-56000
16-29 weeks
1400-53000
2ndTRIMESTER
29-41 weeks
940-60000
3rdTRIMESTER
Sample: Venous blood from arm. No hunger required.
Working day: Every day
Result Time: 2 hours later