What Is A Molar Pregnancy?

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Molar pregnancy is a rare pregnancy condition where the cells (trophoblasts) that usually form the placenta becomes unusual and the growth becomes unusual. If a fetus is present, it will not survive and will be miscarried during the early days of implantation. Molar pregnancies may also develop into a rare form of cancer and it may cause a variety of complications. In the UK, molar pregnancies are quite rare as there is about 1 molar pregnancy for every 590 normal pregnancies seen.


Types Of Molar Pregnancies

There are two types of molar pregnancies that can be seen in this condition. A complete and partial molar pregnancy. In a complete molar pregnancy, there is no fetus present, the placental tissue is swollen and there are fluid-filled cysts present. In a partial molar pregnancy, the placental tissue may be regular, and abnormal placental tissue may be present. There is the possibility of a fetus being present but it will never survive and would have been miscarried early during gestation.


Symptoms of A Molar Pregnancy

The problem with a molar pregnancy is that the symptoms may seem the same as a normal pregnancy. Therefore, we might not be able to differentiate initially between a normal pregnancy and a molar pregnancy. These symptoms include nausea and vomiting, pelvic pressure, pelvic pain, and bleeding from the vagina (during the first 3 months of the pregnancy and the shade of blood may range from bright red to dark brown). A significant symptom is the passing of grape-like cysts from the vagina. During an ultrasound, a “snowstorm” pattern may indicate a molar pregnancy.

Symptoms After the First Trimester

Usually, a molar pregnancy will be found before the second trimester starts but it might be missed. There may be additional symptoms seen in the second semester such as preeclampsia (high blood pressure and protein in the urine), ovarian cysts may form, a uterus growing at an extremely fast rate (too fast for a normal pregnancy) and an overactive thyroid (hyperthyroidism).


What Causes A Molar Pregnancy?

The cause of a molar pregnancy is an atypical fertilised egg. There will usually be a chromosomal fault within the fertilisation. Usually, one egg (23 chromosomes) and one sperm cell (23 chromosomes) come together to form one fertilised egg with 46 chromosomes. There are two types of molar pregnancies and both have their significant cause.

Complete Molar Pregnancy 

In a complete molar pregnancy, the egg is fertilised by one or two sperm cells. The problem arises when the mother’s egg does not contain any chromosomes or the chromosomes are not functional. In this case, the father’s sperm which contains 23 chromosomes, will be duplicated (to create a fertilised egg with 46 chromosomes). None of the mother’s chromosomes will be present.

Partial Molar Pregnancy

The mother’s chromosomes are present in the egg cell (23) but the father gives two sets of chromosomes (46). The fertilised egg will then contain 69 chromosomes after fertilisation instead of the normal 46 chromosomes. This usually occurs when the egg cell has been fertilised with two sperm cells.


Who Is At Risk Of Molar Pregnancies?

Females that fall pregnant before the age of 15 and after the age of 43 are at higher risk of developing a molar pregnancy. This may be due to the underdevelopment of the egg cells before the age of 15 and the decrease in the egg quality and fertility of the female after the age of 43. If a woman has had a molar pregnancy before, she will be at a higher risk of conceiving another one. Every 1 in 100 females that have had a molar pregnancy will develop another molar pregnancy.


Asian women have an increased risk of developing a molar pregnancy. 


Women who have certain dietary deficiencies may be at risk as well. If their diet lacks folate, protein or beta-carotene, they may be at higher risk of developing this condition.


What Complications Could There Be?

The continuation of molar tissue growth even after surgical removal of the molar pregnancy may occur. GTN, gestational trophoblastic neoplasia, is the condition that follows a complete molar pregnancy if all tissue has not been removed. This condition is less likely to occur after partial molar pregnancies. GTN is treated with chemotherapy if the condition keeps returning or a hysterectomy may be performed (removal of the uterus).

Other Complications

In a delayed diagnosis stage or delay in treatment, haemorrhage (bleeding) may occur, and breathlessness if it has spread to the lungs. The female is also at risk of developing an invasive mole where the tumour spreads to the uterus, a metastatic mole where the molar cells travel to other organs and cause secondary tumours or gestational choriocarcinoma where the tumour and cancer spread via the lymphatic system, or the blood vessels.


Diagnosis Of A Molar Pregnancy

The doctor will take a thorough medical history pertaining to previous gestations, miscarriages, or abortions. A physical examination in the doctor’s room will be done as well. Blood tests that may be requestioned are for the hCG hormone which indicates if a female is pregnant or not (higher levels of hCG indicate pregnancy). An ultrasound will be performed and a “snowstorm” appearance may indicate abnormal cell formations in the uterus. Other scans that may be utilised include X-rays, CT scans, or MRIs. These will be used when the doctor suspects that cancer or tumour may have spread to other parts of the body.


How To Treat A Molar Pregnancy

D&C (dilation and curettage) is a form of removal whereby the cervix is opened and the contents of the uterus are evacuated. Another alternative to content removal is to have a hysterectomy performed. 

It is always best to speak to a professional for surgical or medical advice. Contact our specialist GlobMed team today to see how we can help.

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