hCG level: Should this test be routine?
I'm currently eight weeks pregnant, and have had my first prenatal visit. They drew blood, but I was surprised that measuring hCG levels is not common practice at this office. This concerns me, since hCG levels can indicate problems. Shouldn't measurement of hCG levels be routine?Question:
By itself, human chorionic gonadotropin (hCG) levels reveal little. When done in a series, they tell us that the embryo is probably still viable and attachment within the uterus is stable. However, elevated hCG levels can occur with pregnancies destined for poor outcome as well, such as in a molar or ectopic pregnancy. The best evidence of a viable pregnancy at this stage is appropriate uterine growth, a positive pregnancy test and absence of bleeding and cramping.
With biochemical screens such as hCG, comes the risk of a falsely high or low result, which may cause needless anxiety. Furthermore, how would the knowledge of the results change the management of the pregnancy? There is nothing that can be done for the baby or the mother on the basis of only one test. Further evaluation would be needed, which would be done at greater expense. And many of these tests would ultimately be given without cause.
The levels hCG should evaluated if maternal symptoms such as bleeding, cramping or pain occur and the practitioner must decide if the pregnancy is ectopic or within the uterus. Ultrasound finding would be supplemented by hCG results.
We know that hCG levels should increase a certain amount every 36 to 48 hours, and if they do, this is reassuring. But again, this is done only in the case of bleeding or suspicion of an ectopic pregnancy.
At about 15 weeks, every woman should be offered an AFP test. Information on this test should be dispensed at your first prenatal visit. The test can tell you whether or not you may be at a high risk of having a baby with a neural tube defect such as spinal bifida. By that time, you should have received information on folic acid's role in lowering chances of neural tube defects.
Some clinics offer a triple screen, which includes an hCG level, with the addition of estriol and AFP. Such testing can help detect fetal Down syndrome. An association with Down syndrome has been established for low alpha-fetoprotein (AFP), elevated hCG and low estriol levels. The combination of all three biochemical markers, together with maternal age, can be used to calculate a specific, individual risk for Down syndrome.
An abnormal triple-screen result for Down syndrome is not predictive of Down syndrome, however. There is a need to improve the efficiency of serum screening and to more precisely identify pregnancies at high and low risk for genetic disease. The standard of care now is to recommend a targeted ultrasound study if the mother receives an abnormal triple screen or AFP result. Also, the gestational age should be checked again as incorrect dating could cause unexected results.
Normal ultrasonographic anatomy and findings significantly reduce the risk of both Down syndrome and any significant chromosome defects in pregnancies with abnormal triple-screen results.
I hope this answers your question. It is not common practice to offer an hCG test, but you should start thinking about whether or not you wish to have an AFP or triple screen at 15 to 20 weeks.Answer: