Molar Pregnancy- Causes, Treatment and Prevention

Definition

Molar Pregnancy often referred to as Hydatidiform Mole is a rare pregnancy complication. Molar pregnancy is basically a type of gestational trophoblastic disease that occurs when tissues that instead of normally developing into a fetus, turns into an abnormal growth. The condition is characterized by unusual growth of trophoblasts, the cells which normally develop and form a major part of the placenta in pregnancy.

A molar pregnancy can be a scary thing as the growth inside is not an embryo but a chromosomal abnormality. The abnormal tissue needs to be treated right away as it can cause serious complications in some women.

Types of Molar Pregnancy

There are two main types include:

Complete molar pregnancy

The fertilized egg of a healthy pregnancy is made up of 23 chromosomes from the mother and 23 chromosomes from the father.

In a complete molar pregnancy, genetic material from the mother is lost at the time of fertilization.  The egg contains only 23 chromosomes from the father and no chromosomes from the mother at all. This means that there is no baby.

The placenta develops rapidly with abnormal cells that grow as cysts. These cysts grow in clusters and can be seen on ultrasound. They are referred to as a mole.

Partial molar pregnancy

In a partial molar pregnancy, the egg has the usual 23 chromosomes from the mother but is fertilized by two sperm, each with 23 chromosomes which makes 69 chromosomes in total rather than the normal 46.

Some normal placental tissue forms among the abnormal cells and a baby may begin to develop, but it will be genetically abnormal and unable to live beyond 3 months.

Risk factors

Things that may increase your risk include:

Age: The risk of complete molar pregnancy steadily increases after age 35.

A history of molar pregnancy, especially if you’ve had two or more.

A history of miscarriage

A diet low in folic acid or carotene: Carotene is a form of vitamin A. Women who don’t get enough of these vitamins have a higher rate of complete molar pregnancy.

Causes of Molar Pregnancy

It is not fully understood why molar pregnancies happen. However, molar pregnancies are more common:

  • In teenagers and women in their 40s
  • In women from Asia
  • If you have had a molar pregnancy in the past

Symptoms 

At first, your pregnancy might seem normal. But over time, you may start to notice the following:

  • Bleeding from your vagina in the first 3 months of pregnancy
  • Watery brown discharge
  • Sacs (they look like clusters of grapes) that pass out of your vagina
  • Nausea and vomiting that are more frequent or severe than what’s normal during pregnancy
  • Lots of pressure or pain in your pelvis

Call your doctor if you have these or any other unusual symptoms during pregnancy.

Complications

Molar pregnancy is usually diagnosed early with minimal symptoms, but if a diagnosis is delayed the following complications can arise:

  • Hemorrhage
  • Ovarian cysts
  • Breathlessness (when it spreads to the lungs)
  • Pre-eclampsia (toxaemia of pregnancy), involving high levels of certain substances in the blood that raise blood pressure and affect the kidneys and (sometimes) liver function
  • Excess thyroid hormone production, which causes heart palpitations and other thyroid hormone effects.

If a molar pregnancy is not treated or does not miscarry completely it can progress and cause a range of serious conditions (known as gestational trophoblastic neoplasia), including:

Persistent GTD- Persistent growth of the abnormal placental tissue

Invasive mole- The tumour spreads into the wall of the uterus

Metastatic mole- Molar cells migrate to other organs of the body and cause secondary tumours. The lungs are common sites for metastatic moles

Gestational choriocarcinoma- A rapidly spreading type of cancer that can travel to any part of the body via the blood vessels or lymphatic system.

Diagnosis and test

Molar pregnancy is diagnosed using:

  • Medical history, which could include current pregnancy or recent childbirth, miscarriage or abortion
  • Physical examination
  • Blood test to check for high levels of the pregnancy hormone hCG
  • ultrasound (the most common imaging tool used)
  • Other scans including x-rays, computed tomography (CT) or magnetic resonance imaging (MRI) if it is thought cancer may have spread to other areas of the body.

Molar pregnancy can be hard to diagnose because:

  • A woman who experiences a miscarriage will not know whether or not she passed a hydatidiform mole unless the aborted tissue is examined in a laboratory.
  • If recent pregnancy, labour, and birth were normal, there is often no reason to suspect molar pregnancy until symptoms become apparent.

Treatment and medications

A molar pregnancy can’t continue as a normal viable pregnancy. To prevent complications, the abnormal placental tissue must be removed. Treatment usually consists of one or more of the following steps:

Dilation and curettage (D&C): To treat a molar pregnancy, your doctor will remove the molar tissue from your uterus with a procedure called dilation and curettage (D&C). A D&C is usually done as an outpatient procedure in a hospital.

During the procedure, you’ll receive a local or general anesthetic and be positioned on the operating room table on your back with your legs in stirrups. Your doctor will insert a speculum into your vagina, as in a pelvic exam, to see your cervix. He or she will then dilate your cervix and remove uterine tissue with a vacuum device.

Hysterectomy: Rarely, if there is an increased risk of gestational trophoblastic neoplasia (GTN) and there’s no desire for future pregnancies, the uterus may be removed (hysterectomy).

HCG monitoring: After the molar tissue is removed, your doctor will repeat measurements of your HCG level until it returns to normal. If you continue to have HCG in your blood, you may need additional treatment.

Once treatment for the molar pregnancy is complete, your doctor may continue to monitor your HCG levels for six months to one year to make sure there’s no remaining molar tissue. Because pregnancy HCG levels also increase during a normal pregnancy, your doctor may recommend you wait six to 12 months before trying to become pregnant again. Your provider will recommend a reliable form of birth control during this time.

Prevention

It is not much you can do to prevent a molar pregnancy. Should one occur, there are some serious but uncommon risks, including:

  • Dangerous levels of bleeding if your body passes the tissue on its own.
  • Possible development of cancerous tissue if some of the mole remains inside your uterus.
  • Although it is distressing to find out that you have a molar pregnancy, the good news is that it is manageable and that most women who have a molar pregnancy will go on to have healthy pregnancies in the future.

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