A complete molar pregnancy is a pregnancy in which no fetus forms because of a lack of maternal genetic material at conception. When the sperm from the male enters the egg from the female, instead of the genetic material from both parents fusing together, the sperm instead reproduces it’s own genetic material because of the absence of the female counterpart. At this very early point, the cells that begin to grow and divide are completely different from a normal pregnancy. No fetus forms, and the tissue that grows most closely resembles the placenta. Like in a normal pregnancy, this tissue will implant itself in the uterus of the woman and continue to grow.
This causes the women to believe she is pregnant. As the tissue grows, it releases the hormones that a placenta normally produces and causes changes to the woman’s health similar to a normal pregnancy. The woman will experience weight gain and fat deposition and she will also experience morning sickness, which is badly names since it is nausea that can occur any time of the day. One of the most important things that will be noticed is the presence of the HCG hormone. This is a hormone that is only ever produced by the placenta in the body and is what pregnancy test are designed to detect. With all the symptoms the woman is experience, along with a missed period, it will probably cause her to take a pregnancy test, which will come back positive because her ‘placenta’ is producing HCG.
During a molar pregnancy, it is important to remember that the tissue that is forming is not actually a placenta. It is made up of cells that are similar to a placenta, but because there is no fetus, the tissue is markedly different than a normal placenta. One of the ways at which it is different is that it is not able to control it’s own growth similar to a placenta. The tissue grows much more rapidly than a normal placenta, which causes it to be releasing many times the normal amounts of hormones that a normal placenta would produce at that stage of pregnancy. For this reason, the usual signs and symptoms of pregnancy are greatly exaggerated. Another very important thing is that because the tissue is growing rapidly in an uncontrolled way, the blood vessels that feed it are often incomplete. In almost all cases of complete molar pregnancies, the first sign that it is not a normal pregnancy is vaginal bleeding.
Once vaginal bleeding is detected, an ultrasound will be done to confirm if there is a fetus. An ultrasound of a complete molar pregnancy will reveal the absence of the fetus and the presence of the abnormally large placenta which will have a distinct appearance on the ultrasound similar of a bunch of grapes. At this point, the complete molar pregnancy is confirmed. The next important step is a quantitative HCG test. Pregnancy tests are only used to detect the absence or presence of HCG, A quantitative HCG test will tell the doctor exactly how much HCG is currently in the body. This is an extremely important number to know for the treatment of the molar pregnancy.
The treatment for a complete molar pregnancy initially is concerned with removal of the abnormal placenta. This is usually done with a procedure called a D&C; ( dilation and curettage), but if the diagnosis was delayed (past 5 months) and the placenta allowed to grow, sometimes induced labor is used to expel the tissue. In a D&C; procedure, the woman is put to sleep using general anesthesia and the cervix is dilated. A small instrument is then inserted and used to remove the tissue. There is a small risk that the tissue has implanted so deeply into the uterus that the only way to remove the tissue is to also remove the uterine lining, which would result in infertility for the woman. This is very rare though, and normally the tissue is removed without damaging or removing the uterine lining. After the procedure, the woman can expect some slight vaginal bleeding for up to a couple weeks and occasional abdominal pain.
Unfortunately, this is not the end of the story. The abnormal placenta while it is growing is actually similar to a cancer. Because it is has access to the woman’s bloodstream, there is a small chance that some of the placenta cells separated from the tissue and entered the bloodstream and were deposited at a distant location. This most frequently occurs in the lungs, but also can occur in the liver, bones or brain. When this happens, the ‘placenta’ cells continue to grow similar to other types of cancer. At the time of first diagnosis, X-rays are usually done on the lungs, and sometimes other at risk areas to make sure the placenta cells have not already spread.
While the word cancer is a very scary word to use, it is important for the doctor to inform the patient that this particular type of cancer is very treatable, with an almost 100% success rate, and it is also very easy to detect early. The reason it is easy to detect is because while the cells may be growing in the lungs, they are still placenta cells, and still producing HCG. For this reason, and important part of post D&C; treatment is weekly quantitative HCG testing until the levels have reached 0. If HCG levels have not reached 0 within a few months, it is a sign that the placenta cells are still growing somewhere in the body. At this point, it will be necessary to begin chemotherapy. Again, while chemotherapy is a scary word, the type used for molar pregnancies is the least difficult to endure. In most cases, it will involve a single injection.
There is one last piece of information that must be given. It is imperative that very strong birth control measures are taken for one year after a molar pregnancy. The only real danger of a molar pregnancy is that the cells spread to other parts of the body and grow without being detected, which is why repeated HCG testing is so important. What happens if the woman gets pregnant after a molar pregnancy is that her new pregnancy will cause a placenta to form, which will release HCG. Because of this, there will be no way of using HCG testing to detect a cancerous growth in the lungs, brain or other areas. While the normal placenta could be growing to nourish the fetus, another ‘placenta’ could be growing undetected in your lungs. Early detection of a growth will give a nearly 100% success rate with treatment, while an undetected growth in the brain, lungs or liver that is allowed to grow will require much harsher chemotherapy and greatly increases the chance for death.
