Gestational Trophoblastic Disease (GTD)
Gestational trophoblastic disease is a rare complication of pregnancy in which cells (trophoblasts) which feed the embryo and develop into placenta grow abnormally into a mass or tumour.
Molar pregnancy is of two types, Partial molar pregnancy and complete molar pregnancy. In a partial molar pregnancy, both placenta as well as the embryo are abnormal. In a complete molar pregnancy, the placenta is abnormal and there is no embryo.
What is gestational trophoblastic disease?
GTD is a group of conditions that can happen when a pregnancy does not develop properly into a normal fetus but develops into an abnormal tissue (grape like tissue) and GTD includes complete molar and partial molar pregnancy. Sometimes a molar pregnancy can develop into another form of GTD known as gestational trophoblastic neoplasia (GTN). Incidence of GTD has been shown that for approximately every 700 pregnancies which end
What is molar pregnancy?
In a normal pregnancy, an embryo receives one set of 23 chromosomes from the father and one set of 23 chromosomes from the mother, for a total of 46 chromosomes. Thus normal fetus will have 46 sets of chromosomes.
Molar pregnancy is also known as hydatidiform mole and is the most common type of GTD. A molar pregnancy is abnormal from the very beginning of conception as a result of an imbalance in the number of chromosomes which come from the mother and the father.
Molar pregnancy are of two types– complete mole and partial mole.
In a complete molar pregnancy, an empty egg (without genetic material) is fertilized by one or two sperm. The resulting embryo has all of the genetic material from the father. In complete mole, the chromosomes from the mother's egg are absent or inactivated and the father's chromosomes are duplicated. Thus, the resulting embryo will have all 46 set of chromosomes from father. In this type there is no normal fetus but the whole conception will look like bunch of grape like structures.
In a partial mole also known as incomplete molar pregnancy, the egg receives two sets of chromosomes from the father, that’s because two sperm have fertilized the egg. The embryo now has 69 chromosomes instead of the normal 46 chromosomes (23 from mother and 46 from father). In a partial mole, there are some early signs of development of a fetus along with gape like tissue on ultrasound but it is always abnormal and cannot develop into a baby.
Who is at risk of developing GTD?
Age: teenagers and women over 40 years
Race: It is more likely to develop in women of Asian origin
Past history of molar pregnancy. If you've had one molar pregnancy, you're chance of having another molar pregnancy is more likely to have another. A repeat molar pregnancy happens, on average, in 1:100 women.
What are the symptoms of molar pregnancy?
If you have a molar pregnancy you may have –
Spotting or heavy bleeding from the vagina
Sometimes passing grape like structures per-vagina
Excessive morning sickness (hyperemesis)
Your uterus (womb) size may feel larger than your period of gestation
Less commonly, you may develop high blood pressure, symptoms of an hyperactive thyroid gland (hyperthyroid) or tummy pain because of large ovarian cysts
What test will be required for diagnosis?
Most women with a molar pregnancy will present with abnormal vaginal bleeding in the first or second trimester. If your doctor suspects that you may have a molar pregnancy, you will be advised for
Ultrasound scan: in complete mole, there will be no baby inside the pregnancy sac and there may be other signs such as grape like clusters of small cystic or snow-like echoes in the uterine cavity. In partial mole along with fetal parts there may be grape like clusters of small cystic or snow-like echoes in the uterine cavity
Ultrasound may not only helps in diagnosing between complete or partial moles, but it will also confirm presence of any huge ovarian cyst (theca-lutein cysts).
Dilatation and curettage (D&C): This procedure is cleaning up of the uterine content either by scraping or suction to remove the abnormal products of conception for diagnosis and treatment. The tissue obtained will be sent to the lab for diagnosis and confirmation.
Other Tests may include:
Blood tests such as: complete blood count (CBC), blood clotting studies, thyroid test, liver and kidney function test and repeat or serial blood HCG levels.
Chest x-ray and CT scan or MRI of the pelvis and abdomen if cancer is suspected
Can a molar pregnancy survive?
Sadly, molar pregnancy cannot survive. In complete mole there is no fetus and even in a partial mole, though there may be a fetus visible on scan, but it is not developing properly and also cannot survive.
What are the treatment options available?
The initial dilatation and curettage (D&C) to remove the pregnancy tissue for examination and diagnosis might be sufficient treatment. Sometimes if there is continuous bleeding then the doctor will do another D&C (therapeutic) to remove all the residual molar tissue from inside the uterus.
Sometimes after D&C there could be heavy bleeding / hemorrhage causing anemia. Some women may also require a blood transfusion. In a few cases where clotting factors have become abnormal, they may need a life-saving hysterectomy to stop the bleeding.
Do I need special monitoring after D&C?
Following your D&C it is important to monitor the blood hCG level until it becomes negative to ensure no molar tissue remains. The hCG will become negative within three months of the treatment. Prolonged elevation hCG level or continued vaginal bleeding are the common signs of persistent GTD and a risk for a cancerous type of mole.
You will be advised to use an effective contraception method for six to twelve months because if you get pregnant that can become confusing to monitor the hCG levels.
What is persistent gestational trophoblastic neoplasia (GTN)?
Studies have shown that about 20% of women with a molar pregnancy will have a problem of persistent GTD, where trophoblastic tissue (pregnancy tissue) remains in the uterus after the treatment D&C and blood hCG levels remain high. Cancerous part of GTD is GTN and are of two types:
Invasive mole: In this type, the molar tissue erodes deep into the muscle (middle) layer of the uterine wall. Incidence of this is about 20 percent of moles.
Choriocarcinoma: this is cancerous mole and occurs in about 1 to 3 percent of cases. Choriocarcinomas are more common with complete of molar pregnancy rather than with partial moles and they have the tendency to spread to other parts of the body.
What happens if I have gestational trophoblastic neoplasia (GTN)?
If you are diagnosed with GTN, you will require further treatment. If your blood hCG level is less than 5000, you may be advised for D&C. However, if your hCG levels remain high further treatment usually involves chemotherapy drugs. One in seven (15%) women with complete mole and 1 in 200 (0.5%) women with partial mole will need chemotherapy.
Chemotherapy may be of single drug or combination of drugs and the number and type of drugs that are used depend on your age, type of pregnancy, blood levels of hCG before D&C and how long it is since your pregnancy ended. Surgery, such as hysterectomy may be required in some situations.
When can I get pregnant again?
If you had molar pregnancy it will not affect your chance of having another baby. If you are planning for pregnancy, you will be advised to wait for approximately 6 months since completion of follow-up in case of molar pregnancy. But, it you have had GTN then you should not get pregnant for 12 months after your chemotherapy is complete because up to 3 in 100 women (3%) may experience a return of the GTN.
Will I have repeat molar pregnancy?
The risk of a repeat molar pregnancy happening is 1 in 80. This means 98% of the time you will not have a repeat molar pregnancy. It has been advised that after delivery the placenta needs to be sent to the lab to check for any abnormalities.