The tissue that is growing is then usually removed using a procedure called a D C.; The risk, however, is that the abnormal placenta cells of a molar pregnancy growing in the uterus have entered the bloodstream and begin to grow somewhere else in the body. This usually occurs in the lungs, but can also occur in many other organs or in bones.
Fortunately, the abnormal placenta act similar to normal placenta cells and secrete a hormone called HCG. This hormone is what is tested for in pregnancy tests and is only produced by placenta cells. Because only placenta cells produce HCG, and because placenta cells should only exist during a pregnancy, the presence of HCG in the bloodstream is a great way to identify an abnormal placenta growth. In other words, a non-pregnant woman should always have an HCG level that is 0.
Once the abnormal placenta of a molar pregnancy is removed, it normally takes from two to six weeks for all of the HCG to leave the body. It is important in the weeks after the removal of the placenta for HCG testing to be done so that the rapid decrease in HCG levels can be monitored. In many cases, HCG levels while the abnormal placenta is still inside the body can reach 100,000 mui/ml or higher, but in a week or two after the placenta has been removed, those levels should quickly drop below 1000. It is imperative that HCG levels be monitored until they reach 0 or undetectable levels. It is important to note that a test result of 0 does not mean there is no HCG (or placenta cells) still in the body, what it means is that the levels are so low that they cannot be detected by the current test being used. While this is certainly a time to celebrate because it means that the D C; was successful, it is not a time to completely say the risk is all behind you.
There is a very small risk that a few abnormal placenta cells still exist somewhere in the body. Once these cells have established themselves, they will begin to grow, at which time they will begin to produce more HCG. So even after an HCG test gives a 0 or undetectable result, there is a chance that later on, a test result could give a non-zero reading. While this is very unlikely, it is very important to continue HCG testing for up to one year to make sure the test results continue to be zero. There is a very simple reason for this. An abnormal placenta growth that is found early requires a very minimal amount of chemotherapy treatment which is nearly 100% effective. An abnormal growth that is found after six months requires much harsher chemotherapy treatments and the success rate is significantly less than 100%. Because the test is relatively inexpensive, monthly, or even bi-weekly testing is recommended for the first year after the molar pregnancy.
HCG testing following a molar pregnancy is important because of the difference in the chemotherapy needed between an early growth and a growth that has been allowed to grow for long amounts of time. While the amount of HCG found in the body should reach undetectable levels within a few weeks after the removal of the placenta, there is a chance that abnormal placenta cells are still located in the body and could begin to reproduce.