Overview of molar pregnancy

What is molar pregnancy?

A typical pregnancy happens when an egg (ova) is fertilised. A molar pregnancy means that there is a problem with the egg fertilisation which will not result in a baby nor a placenta therefore it won't be able to survive or result in a normal pregnancy.¹

Molar pregnancy, one of the gestational trophoblastic diseases (GTD) is a rare complication of pregnancy. It is either incomplete (partial) or complete. In the complete form, the uterus is filled with grape-like cysts and no fetus is formed. However, in partial form, a fetus may be present but can not survive as the placenta is irregular and abnormal to carry on its functions. Molar pregnancy is sometimes called a non-cancerous tumour.^2,3

Who is likely to have a molar pregnancy?

• Extremes of age: pregnancy before the age of 20 or after the age of 40 raises the risk
• History of molar pregnancy
• History of more than 2 abortions
• Asian ethnicity

Molar pregnancies are very rare, occurring in less than 1% of all pregnancies, or around one in every 1,000.⁴

Symptoms and diagnosis of molar pregnancy

Molar pregnancy is usually diagnosed during a routine pregnancy ultrasound scan or as a product of an abortion. Therefore, sometimes it may not present with any symptoms.

Nevertheless, if you have the following symptoms, seek your obstetrician for more confirmation:⁵

• Severe unbearable nausea and vomiting due to excessive circulating hormones of this abnormal pregnancy
• Vagninal bleeding which is brown, usually begins in the 6^th till the 12^th week of pregnancy
• Pain in your pelvis or the sensation of pressure
• Grape-like structures coming out of your vagina along with the bleeding
• Anaemia as a result of bleeding
• Preeclampsia, which is increased blood pressure usually occurs in the last three months of pregnancy but here in molar pregnancy,  it occurs early
• Overactivity of the thyroid gland (hyperthyroidism)
• Abnormally big uterus for its age, not correlating with its usual size at a specific month of pregnancy

When it comes to diagnosis, molar pregnancy is diagnosed by blood tests, pelvic ultrasound and your medical history. The most confirmatory method is by laboratory analysis of the molar tissue when it is removed surgically from the womb. Molar tissue secretes a hormone called human chorionic gonadotropin (HCG), frequent blood or urine tests are needed to assess its levels.

Treatment options

Surgical treatment

It includes getting rid of the abnormal molar tissue that is formed in the uterus in addition to confirming the diagnosis. This occurs by either of:⁶

• Dilatation and curettage (D and C)

The entrance of the womb is opened by your surgeon using a small instrument and scraps the lining of the womb to remove any molar tissue.

• Dilatation and suction evacuation (D and E)

This one differs from D and C in that the surgeon opens the entrance of the womb and uses gentle suction to evacuate it from the molar tissue. In both methods, the surgeon uses ultrasound to ensure that there is no remaining molar tissue and then it is sent for a pathological checkup in the laboratory.

After both of the above operations, you should stay in the hospital for a few hours to be checked up as there will be bleeding for 2 weeks. It is better to contact your doctor if you think your bleeding is heavy or if you developed intense unusual pelvic pain. During these 2 weeks, you should abstain from sex, tampons and scented soaps to avoid being infected.

• Removal of the uterus (hysterectomy)

It is the removal of the womb either by open surgery, laparoscopic which means that your surgeon will insert tubes through a small cut in your lower abdomen to remove the womb, or through vaginal surgery. As this is a slightly more complex operation than D and C or D and E, you usually stay longer in the hospital for follow-up and you need to rest for a longer period postoperatively, ranging from 4 to 6 weeks. During this time, you will be advised to rest, avoid any heavy housework or lifting any objects to avoid any pressure on your abdomen and give the chance for the wound to heal properly.

After the molar tissue is removed, the HCG level is monitored until it decreases. If its level remains high, further therapy may be required. Following surgical evacuation, guidelines from the British Blood Transfusion Society and the Royal College of Obstetricians and Gynaecologists suggest that all Rhesus-negative, (which is a blood group subtype) women with molar pregnancies get 250 IU anti-D immunoglobulin.⁷

Medical treatment

The tablets or pessaries (a large tablet that goes in the vagina), called oxytocic drugs are prescribed, which allow the opening of the entrance of the womb and allow the passage of the molar tissue out of it. You will have to take painkillers along with these medications as it causes severe tummy pain with some vaginal bleeding, but luckily this does not take too long, not more than a few hours.⁸

After the treatment, the passed molar tissue is routinely sent to the laboratory for checking and you will stay in the hospital for maybe one more night to assess bleeding. If after you have been sent home you experience heavy bleeding, go back to the hospital straight away.

Follow up

It is very important in all cases of molar pregnancy to determine who are the residual cases. These are the cases who removed the tissue surgically or medically but still, in their follow-up, they showed some molar tissue left. After treatment for the molar pregnancy is completed, a physician may monitor HCG levels for six months to ensure that no molar tissue remains. HCG levels in molar disease patients are monitored for a year after treatment is done. Because pregnancy HCG levels grow throughout a normal pregnancy, the physician may advise you to wait 6 to 12 months before attempting to conceive again. During this period, you might be offered a dependable method of birth control.

If you were confirmed by the laboratory to have a partial molar pregnancy, you will have to have blood and urine sample tests 4 weeks after your HCG becomes normal. However, if you have a complete type, you will follow up for 6 months after your treatment and after your HCG levels become normal.⁹

On the contrary, if your HCG levels in the blood did not go down after treatment, this indicates that there are some abnormal molar cells left, which is called invasive mole or persistent trophoblastic disease (PTD). It is a more common sequela in complete molar disease rather than partial one.

Future pregnancy considerations

Pregnancy during the follow-up period should be avoided so patients will be offered contraception methods usually the oral type. However, if pregnancy happens, then the physician should know so as not to get confused between the rising levels of HCG hormone, whether it is from the cured molar disease or from the new pregnancy.

Pregnancy with a molar disease does not impact the likelihood of becoming pregnant again. However until the follow-up plan is finished, patients should wait to get pregnant after a molar pregnancy. Periods are often stopped while receiving chemotherapy for PTD. After finishing chemotherapy, periods almost usually resume a few weeks to months later, and more than 80% of the women who have received chemotherapy for PTD become pregnant again. Fertility will not recover following treatment if a high dosage of chemotherapy is given, which is uncommon. It is advisable to wait a full year after finishing chemotherapy for PTD before becoming pregnant again.¹⁰

Summary

A molar pregnancy is a rare complication where abnormal tissue grows in the uterus instead of a normal pregnancy. Treatment involves surgical removal of the molar tissue using dilatation and curettage (D&C) or dilatation and suction evacuation (D&E). For these treatments, the uterus is opened, and the abnormal tissue is removed. To ensure complete removal of the molar tissue, ultrasound guidance is frequently used. Hysterectomy, or the surgical removal of the uterus, may be required in extreme circumstances. Patients are monitored after surgery for complications including vaginal bleeding, and routine blood or urine HCG are regularly checked. Chemotherapy may be required for persistent high HCG levels. Follow-up involves monitoring HCG levels and waiting before attempting pregnancy again