You have been diagnosed with a hydatidiform mole, also known as a molar pregnancy. The loss of your baby understandably makes you feel very sad. It is also likely that this is the first time you are hearing about this condition, which may leave you feeling shocked, confused, and anxious about the future.
The purpose of this section is to explain what a hydatidiform mole is and why it is important for women who have experienced a molar pregnancy to follow specialized treatment. All the information has been carefully reviewed. You need to understand what has happened and why your doctors have recommended a specific course of action. Definitions and explanations of the medical terms used can be found in the final pages.
How does a normal pregnancy develop?
The sperm meets the egg in the fallopian tubes, which lead toward the ovaries—the place from which the egg was released a few days earlier. The sperm reaches the egg, and the fertilised egg then moves toward the cavity of the uterus. During fertilisation, the genes from the sperm mix with those of the egg to produce the characteristics of the baby that will be born.
Genes, which exist in all our cells, are called chromosomes. These chromosomes contain a system for passing on information through a series of chains of a chemical substance called DNA. By the time the fertilised egg reaches the uterus, all the information has been distributed and divided into two main groups of cells.
The trophoblast is the part from which the placenta (after birth) and the membranes develop. Another name for this tissue is the chorion.
The trophoblast enters the uterine lining to initiate the pregnancy and facilitate its progression. This is called implantation. The placenta and the embryo both begin to form. After a few weeks, it becomes a recognisable baby (or fetus, as it is called while inside the uterus). The baby grows, and its organs gradually begin to function on their own, and after 40 weeks from your last menstrual period, he or she is born healthy.
Many pregnancies—probably 50–60%—fail either before implantation occurs or within the first 3 months. This is known as a miscarriage. Rarely, other problems may occur, such as a hydatidiform mole. The next section describes this
What is a hydatidiform mole?
This unusual name is an older term used to describe a mass of fluid-filled cells. It occurs when the trophoblast (or chorion) grows in an uncontrolled way and fills the uterus instead of developing into a normal embryo. Because it swells and expands to fill the uterus, a hydatidiform mole is part of a group of rare conditions called trophoblastic tumors. Pregnancies affected by this condition are known as molar pregnancies. They occur in about 1 in every 1,200 pregnancies.
There are two types of molar pregnancies: complete and partial hydatidiform mole. In some cases, molar tissue can persist and continue to grow or spread, a condition known as an invasive mole. Choriocarcinoma is a rare complication of a hydatidiform mole.
Complete mole
We have already mentioned that the egg and the sperm join together and share their genetic material (DNA). Sometimes, the egg does not carry any genetic information, and therefore, when it joins with the sperm, the genetic sharing cannot take place. Usually, the egg at this stage dies, but in rare cases, it may still travel to the uterus and implant. When this happens, an embryo does not develop. Instead, the trophoblast grows in an uncontrolled manner. This is known as a complete hydatidiform mole.
Partial mole
In this case, the egg allows two sperm to fertilise it (something that would normally be impossible). As a result, there is an excess of genetic material, and the pregnancy develops abnormally, with the placenta outgrowing the baby. The embryo may not exist at all, but even when present, it does not develop normally. There are a few reports of babies being born after a partial mole, but this is believed to be the result of a very rare situation in which a baby has a “twin” that is a molar pregnancy.
Invasive mole
We have already seen that one of the functions of the trophoblast is to penetrate the lining of the uterus. This is essential for the formation of the placenta and for keeping it attached inside the uterus. Sometimes, the trophoblast of a complete molar pregnancy grows much deeper into the uterus than it should. In rare cases, it may even extend beyond it. It is not cancer, but it must be recognized and treated appropriately (as described below).
Choriocarcinoma
In this rare type of tumor, the trophoblastic cells become disorganized and are able to invade and spread to other parts of the body. They have become cancerous. Some choriocarcinomas develop after a complete molar pregnancy, but very rarely they may occur sometime after a normal pregnancy, a miscarriage, or a termination of pregnancy. It must be stressed that this is extremely uncommon. The small risk of choriocarcinoma is the reason why a patient must be monitored after a molar pregnancy. It is usually detected early, and when it is, treatment is 100% successful.
What symptoms will I experience with a molar pregnancy?
One of the hormones produced by the trophoblast is human chorionic gonadotropin (hCG). One of the functions of hCG is to help the ovaries produce the hormones necessary for the development of pregnancy. Most symptoms of a molar pregnancy are the result of the excessively high levels of hCG produced by the rapidly growing trophoblast. Therefore, the symptoms may include:
- You will not have a period
- Severe nausea and vomiting
- Irregular vaginal bleeding — the blood may contain small, fluid-filled cysts
- Symptoms similar to those of a miscarriage between the 8th and 16th week
The uterus will be larger than expected for the gestational dates, and sometimes hCG can cause the ovaries to enlarge. In rare cases, a molar pregnancy can cause high blood pressure and protein in the urine (pre-eclampsia or toxemia).
How is it diagnosed and treated?
A. If you visit your doctor and they suspect a molar pregnancy, they will arrange for the following:
- A blood test to measure human chorionic gonadotropin (hCG)
- An ultrasound scan
- An examination by an obstetrician–gynecologist
B. If the diagnosis is confirmed, you will be referred to a gynecological team. They will advise you to be admitted to the hospital for surgical removal of the mole by suction, in which a surgical instrument is passed through the cervix while you are under general anesthesia. This procedure is called suction evacuation of the mole. You will stay in the hospital for 24 to 48 hours, depending on your condition, for monitoring. It is important to understand that this procedure is not a “termination of pregnancy” or an “abortion.” In most cases, there was no embryo, and even in a partial mole, the embryo cannot develop. You should not feel guilty. You may still feel sad about the loss of the pregnancy.
C. The tissue will be sent to the laboratory for examination, and you will be informed of the results. (See also “How can I help myself?”)
D. A series of blood serum tests will be done over the following months to check for the presence of hCG. If any molar tissue remains, the hCG levels will not fall, or they may even rise. In most women, hCG levels fall very quickly. If your serum hCG levels drop to normal levels (4 IU/L or lower) within 8 weeks, monitoring will continue for 6 months.
If hCG levels take more than 8 weeks to return to normal, monitoring will continue for 2 years after they become normal again. If levels remain steady or begin to rise again, treatment will begin. These are general guidelines, but each woman is treated as an individual.
Monitoring results will be sent to your GP or your gynecologist. If you wish to obtain your results directly, you may call the follow-up service (wait 3 days after your sample is taken), and they will tell you your levels and your progress.
Results from your urine and serum are measured in IU/L — international units of hCG per liter. ‘Normal’ serum levels are less than 5 IU/L. Once your hCG levels have remained normal for 6 months, you may try to become pregnant again.
In future pregnancies, an ultrasound scan will help reassure both you and your doctor. Care during pregnancy should be shared between your doctor, midwife, and hospital. Even if you do not become pregnant again, it is advisable to have periodic check-ups.
Fewer than 10% of women require further treatment with medication (chemotherapy). This may involve a hospital stay, during which you will receive one or more drugs to destroy any remaining molar cells. The treatment is highly effective and will not affect your ability to have children in the future. If treatment is recommended, your doctor will provide you with full guidance.
What does the follow-up process involve?
The procedure is very simple:
- You will receive a letter from the follow-up department stating that you have been registered in the monitoring program.
- You will then receive a small package containing a letter from your local hospital or clinic and a small container.
- On the date indicated, collect a urine sample in the container. The next time you visit the hospital for your blood test, you will be given a second container.
- Both containers will be placed in a box, along with a form you will complete with information about your last menstrual period and any medications you are currently taking. The box will be sealed and sent (no postage is required). As long as the blood test remains normal, only the urine sample will be needed.
What will happen if I have choriocarcinoma or an invasive mole?
The purpose of the follow-up process is to detect choriocarcinoma or an invasive mole, and you will be given clear instructions and guidance in the rare event that either condition is identified. Blood samples will likely be needed from both you and your partner to check blood group and tissue type, so that the most appropriate treatment can be determined. Special tests, including X-rays, CT scans, and MRI scans, may be required to assess the extent of the problem. Treatment with medication (chemotherapy) is highly successful, and once it has been completed, you will be able to become pregnant again. The risk of having a baby with abnormalities is not increased by the chemotherapy.
How can I help myself?
- Always send the samples when they are requested. The urine sample must contain your first urine of the day.
- Do not become pregnant during the follow-up period. A pregnancy will produce hCG levels similar to those seen if molar tissue starts growing again, making it more difficult to detect a recurrence. It is very important to inform the follow-up department if you become pregnant.
- If your hCG levels are above normal, do not use contraceptive pills, as taking them may prolong the life of any remaining molar cells. If you wish to use contraceptive pills, wait until your levels have returned to normal and then discuss it with your GP or gynecologist. Do not start taking the pill without informing the follow-up department. Condoms with spermicide, creams, and gels are the recommended forms of contraception while your tests are not yet normal. As with all methods of contraception, these are provided free of charge by your GP or the hospital.
Questions and Answers
Review
Do I have cancer?
If you had an invasive hydatidiform mole, then you do not have cancer. However, a small percentage of molar pregnancies can develop into choriocarcinoma, which is a form of cancer. Fortunately, it is a type of cancer that is 100% curable.
Is there a risk of death?
Absolutely NOT. Today, women do not die from hydatidiform or invasive moles, and only very rarely from choriocarcinoma.
I feel different because of the molar pregnancy — what can I do?
This is a very common feeling. There is nothing unnatural about molar tissue. Trophoblastic tissue is present in every pregnancy and is completely normal. A mole is different only because its trophoblastic growth did not stop at the right time. You did not grow anything monstrous or unnatural inside you. It was simply a pregnancy without a baby to regulate it. You are the same woman you were before, and unless you develop choriocarcinoma, you do not have cancer.
Can I start the contraceptive pill while I am being monitored?
It is best not to use contraceptive pills while your hCG levels are elevated. The reason is that the pill may stimulate molar tissue to grow, increasing the likelihood that you will need further treatment. If you decide to take the pill, you must inform both your GP and the follow-up department. This is very important.
What other contraceptive methods are there?
A condom with spermicide is suitable and effective when used correctly. The rhythm method, temperature charting, and cervical mucus monitoring can also be effective, although their reliability varies. An intrauterine device (coil) should not be used until your hCG levels have returned to normal. You may start the contraceptive pill once your hCG levels are normal (see above). Overall, you should speak with your doctor or someone from the follow-up department.
How long will the follow-up process last?
The shortest follow-up period for complete or partial moles is 6 months. If you require treatment, you will continue to be monitored afterward to ensure your hCG levels remain normal.
Can I become pregnant again?
Yes. A molar pregnancy does not affect your fertility. Many women have had healthy pregnancies after a molar pregnancy.
Will I have another hydatidiform mole?
It is possible but rare. The risk for a woman who has never had a molar pregnancy is 1 in 1200. If you have had one mole, the risk increases to 1 in 80. If you have had two moles, the risk of a third is 1 in 6. What you should remember is that the chances of having a perfectly normal pregnancy are still very high.
Am I more likely to have a miscarriage?
We cannot say for certain, but the answer is “probably not.”
If I need chemotherapy, is my baby at higher risk of birth defects in a future pregnancy?
We cannot give a definite “no,” but there is no strong evidence suggesting an increased risk.
Do I have to wait 6 months before becoming pregnant again?
For complete and partial moles, the answer is usually yes. You must wait 6 months to allow time for any remaining molar cells to begin growing again. If they do, your hCG levels will rise, and treatment will be given to destroy the cells. Six months may feel like a long time, but it ensures your safety. Do not try to become pregnant until your gynecologist confirms it is safe.
Is there anything I can do to reduce the risk of recurrence?
No.
Can my partner catch anything from me because of the mole?
No.
Medical Terminology
We have tried to use as few medical and scientific terms as possible. Here you will find explanations of the terms we used, as well as others that you may encounter during your treatment.
Analysis (test)
Scientists use this term when they want to measure something chemically. Human chorionic gonadotropin (hCG) is usually analyzed using Radio Immune Assay (RIA).
Dilation and Curettage (D&C)
Dilation and curettage is a minor surgical procedure in which the cervix is dilated and the lining of the uterus is scraped using a sharp instrument called a curette. When this procedure is used during early pregnancy, it is called Evacuation of Retained Products of Conception (ERPC).
Fetus
The baby in the early stages of pregnancy.
Fetus
The unborn baby.
Human Chorionic Gonadotropin (hCG)
An important hormone produced during pregnancy. It is produced by trophoblastic cells. hCG is used in pregnancy tests and is also the hormone measured during the monitoring of molar pregnancies. Biologically, the function of hCG is to maintain the pregnancy.
Metastasis
The process by which cancer spreads.
Mole
A mass of cells. Common moles are the dark spots on the skin, which are clusters (moles) of pigmented skin cells. A hydatidiform mole is a mass of trophoblastic cells. These two types of “moles” are unrelated.
Placenta
The placenta is an organ that nourishes the fetus and removes waste products. The cells located between the mother and the baby are trophoblastic cells that did not develop into placental tissue.
RIA
A highly sensitive measurement method that uses radioactive tracers (isotopes). It is performed only in laboratories that comply with safety standards.
Trophoblast
The trophoblast, or chorion, is the thin layer of cells that separates the mother from the baby.
Tumor
Essentially, a swollen mass is similar to a mole. Any mass of cells located in the wrong place can be called a tumor. It does not mean the cells are cancerous.
Uterus
A muscular organ in which the fetus grows. It is lined with a thin layer of tissue called the endometrium, which allows the fertilized egg to implant and the fetus to grow. The endometrial cells are the ones that break down each month and cause menstruation. These are also the cells scraped away during a dilation and curettage (D&C) procedure.
