Complete Molar Pregnancy: Causes, Treatment & Risks

A molar pregnancy or a hydatidiform mole is a benign tumor that develops in the uterus due to the presence of an extra set of male chromosomes in the fertilized egg. Due to this extra set of chromosomes, a growing mass of cysts forms in place of the placenta.

Molar pregnancies can be of two types, partial and complete. While in a partial molar pregnancy there is an abnormal embryo, in a complete molar pregnancy there is neither any embryo nor any normal placental tissue. Molar pregnancies can lead to serious complications which include a rare form of cancer and for this reason should be treated as soon as a diagnosis is made.


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Complete Molar Pregnancy


Initially, a complete molar pregnancy develops like a normal one. Some of the earliest signs and symptoms that may indicate a complete molar pregnancy include:

  • Vaginal bleeding or spotting during the first trimester
  • Severe nausea and vomiting
  • Passage of grape-like cysts from the vagina
  • Excessive pressure or pain in the pelvic region

Any of these symptoms are cause for concern and warrants an immediate visit to the doctor. Further examination may reveal other symptoms such as:

  • Abnormal growth of the uterus
  • Preeclampsia, which is a condition resulting in high blood pressure and protein in the urine
  • Ovarian cysts
  • Anemia
  • Hyperthyroidism or an overactive thyroid
  • Absence of fetal movement or heartbeat


An abnormally fertilized egg is what causes a molar pregnancy. A normal human cell contains 23 pairs of chromosomes with each pair containing one chromosome from the father and one chromosome from the mother. A complete molar pregnancy occurs when all the chromosomes in the fertilized egg are the father's. This happens shortly after fertilization, when the mother's chromosomes are lost and the father's chromosomes get duplicated. There may be an inactive nucleus or no nucleus at all in the fertilized egg.


Complete molar pregnancies are a relatively rare occurrence. Some of the risk factors associated with complete molar pregnancies include:

Age of the mother – Women over the age of 35 years or under the age of 20 years are at a higher risk
Prior history of molar pregnancy – Women who have had a molar pregnancy previously are much more likely to have another
Ethnicity – Southeast Asian women have a higher risk of molar pregnancy
Women with a history of miscarriage


Your doctor may order some additional tests if he or she suspects a molar pregnancy. These include:

  • Blood test: A blood test to detect levels of human gonadotropin (HCG) may be performed. Elevated levels will signify a molar pregnancy.

  • Ultrasound scan: An ultrasound scan will detect the absence of an embryo, amniotic fluid, ovarian cysts and a uterus filled with a thick cystic placenta. These will confirm either a complete or a partial molar pregnancy.

Molar pregnancies cannot be allowed to continue as a normal pregnancy. To avoid complications it must be terminated by the removal of the molar tissue.

The tissue will be removed by your doctor using a process known as dilation and curettage (D&C). The procedure will be performed in a hospital using general or local anesthesia and takes from 15 to 30 minutes. The uterine tissue is removed using a vacuum device.

In cases of extensive molar tissue and if no further pregnancies are contemplated, the doctor may recommend the complete removal of the uterus.

If HCG levels in your blood are still high after the D&C then you may require additional treatment. Your HCG levels will be monitored regularly for up to 1 year to ensure that there is no molar tissue left over from the D&C. Your doctor will recommend that you do not attempt to conceive again for that duration.

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