Molar Pregnancy

Molar Pregnancy


What is a Molar Pregnancy

Molar pregnancy (chorioadenoma) is diagnosed in cases when a fertilized egg cannot develop into a normal embryo (in this case, the embryo is called a mole, hence the name). Initially, a woman can feel the signs of a normal pregnancy, which occur during the hydatidiform mole, but finally, she will start bleeding or have symptoms, indicating that the pregnancy is progressing in the wrong way. In fact, chorioadenoma cannot be a pregnancy, because in this state, firstly, the placenta is formed incorrectly, and secondly, the formation of the embryo does not occur.

Fortunately, molar pregnancy is diagnosed very rarely, only in 1 out of 1,500 cases. The main risk factors for developing this condition is a woman’s age, which is less than 20 or more than 35 years old, as well as, previous chorioadenoma occurrence. 

Reasons for Molar Pregnancy

A molar pregnancy occurs when there is a problem of genetic information transmission (of paternal and maternal chromosomes) in the fertilized egg at the moment of fetation. The result of this problem is that the egg may develop either from paternal cells (complete molar pregnancy) or only from paternal and maternal, but the amount of paternal cells will be twice as large (partial molar pregnancy). Both the first and the second states are anomalies, because during normal pregnancy the fertilized egg contains 23 chromosomes derived from mother, and 23 obtained from father.

In case of a complete molar pregnancy the egg contains two paternal chromosomes and none of maternal. In this case the tissue of the placenta is not formed, the embryo does not appear and the amniotic cavity is absent. Instead, the placenta forms a large cyst, seemingly resembling a bunch of grapes.

In most cases of partial molar pregnancy, in the fertilized egg there is a normal set of maternal chromosomes (23) and two sets of paternal chromosomes (46), which are in the amount of 69 chromosomes, instead of 46, as in normal state. This can happen in two cases: when the sperm chromosomes are duplicated or when one egg is fertilized by two sperm cells.

In case of partial molar pregnancy development, the placenta is formed of two types of tissue – normal and abnormal. In this case, the embryo is starting to develop, and during ultrasound, the specialist can see an amniotic cavity, fetal membranes, and even a fetus. However, despite the fact of fetus development at this time, its evolution is abnormal, and it fails to survive!

Symptoms of Molar Pregnancy

Molar Pregnancy 1

At the beginning, the woman may notice the typical symptoms of normal pregnancy, but at the certain moment, she may have bloody vaginal discharge, which can quickly turn into a heavy bleeding. The blood may be bright red (scarlet) to brown (“clotted”) color, and the bleeding may be continuous or periodic. In most cases, the bleeding starts between the beginning of the sixth and the end of the twelfth week of pregnancy.

The woman may have severe nausea turning into vomiting, crampy abdominal pains and heavy stomach bloating because the uterus, during the molar pregnancy, increases in size much faster than it occurs during normal pregnancy.

Some women may have the aggravation of this condition, which leads to a heavy preeclampsia, especially, when chorioadenoma is not diagnosed in time. Fortunately, it happens very rare, because the ultrasound scan can detect the molar pregnancy in its very early development, which helps to avoid such serious consequences as preeclampsia or eclampsia of pregnancy.

It is urgent to call your doctor or go straight to the hospital if you have vaginal bleeding during pregnancy. Of course, this symptom does not always indicate chorioadenoma, but in case of bleeding, the doctor will suggest the ultrasound investigation to define its cause, and recommend the blood test for detecting the levels of the hormone hCG (human chorionic gonadotrophin). In cases of molar pregnancy, during ultrasound scans the doctor may observe cysts in shapes of grape bunches, and the hCG levels will be much higher than it should be for the gestation.

Molar Pregnancy Treatment

If the molar pregnancy diagnosis is confirmed, it will require an uterus cleaning procedure (curettage procedure) and a vacuum extraction (approximately the same procedure as during the mini-abortion) to remove the scraped abnormal tissue from the uterus. This procedure can be done under general or local anesthesia.

During the uterus cleaning procedure, the doctor inserts a dilator into vagina, treats the cervix and vagina with antiseptic solution, and expands the cervix with the help of thin metal rods. In the cervix, he inserts a hollow plastic tube, through which he absorbs the abnormal tissue from the uterus. Then, using a curette – a special surgical instrument shaped like a spoon, the doctor gently cleans the remained tissue from the uterine walls.

After the curettage procedure, the woman is required to monitor the hCG levels for a week to make sure it is reducing (the reduction of hCG levels indicates that no molar tissue parts remained in uterus). After the hCG levels fall to zero (this may happen in the period of a few weeks), it is necessary for the woman to check its levels every month or two during the year.

Sometimes, even after the tissue removal, the abnormal cells may still remain in the uterus. It occurs in 11 % of cases of partial molar pregnancy and in 18-29 % of cases of complete molar pregnancy. This condition is called a persistent gestational trophoblastic neoplasia (or a stable molar pregnancy). In most cases, stable molar pregnancy is treated with chemotherapy, but in some cases (1out of 30,000-40,000 cases) chorioadenoma turns cancerous, called gestational choriocarcinoma.

Gestation after Molar Pregnancy

No matter what treatment methods have been taken, it is necessary to wait for a year after the hCG levels lower to zero before trying to become pregnant again. The attempts at getting pregnant before may increase the hCG levels and this can make it difficult for a doctor to determine whether a pregnancy is normal.

One thing is for sure: chorioadenoma does not affect women's fertility or ability to have a normal pregnancy, even if you have passed through chemotherapy. Also the occurrence of molar pregnancy in the past does not increase the risk of premature birth, inborn defects, stillbirth and other complications for future pregnancy. And the probability that the next pregnancy may be molar is very negligible– only 1-2 %. The most important is to get an ultrasound scan during the first trimester of the following pregnancy to make sure that all is well.

Unfortunately, very often the obstacle for the future fetation may be the psychological state of a woman. Indeed, the bitter experience of having a molar pregnancy can be compared with the grief of losing a child from a miscarriage or an ectopic pregnancy. Women may often feel ruined and defective, that is why before attempting fetation, it is important to cope with the grief and to be psychologically prepared for the future pregnancy.

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