Hydatidiform Mole (Molar Pregnancy): Causes and Treatments


What is Hydatidiform Mola

Also known as molar pregnancy or spring pregnancy, the hydatidiform mole is a tumor caused by a complication of pregnancy and is part of a set of conditions called Gestational Trophoblastic Tumors. Normally, this disease occurs during the process of fertilization of the egg with the sperm and, although it is a rare condition, it is possible to happen.

The cells that are designed to form the placenta develop in a completely abnormal way, so what ends up forming is a pile of cells and, unfortunately, not a baby. For this reason, pregnancy affected by hydatidiform mole has no way of going ahead and needs to be stopped as soon as possible. In most cases, this tumor is benign, but in 1% to 3% of cases it can become malignant.

The causes and types of the disease

The hydatidiform mole is caused by a problem in the genetic information of the egg with the sperm. Currently, there are two classifications for the disease: the complete hydatidiform mole and the partial hydatidiform mole. See below how each one develops:

Mola hidatiforme completa

In a normal pregnancy, the fertilized egg has 23 pairs of chromosomes, that is, 23 from the mother and 23 from the father. In a pregnancy that suffers from the complete hydatidiform mole, the egg does not receive the chromosomes from the mother and those from the father come in duplicate. As a result, there is neither the formation of the embryo nor the placenta, which is noticeable are several cysts together in the uterus that resemble a bunch of grapes .

Mola hidatiforme parcial

In the case of the partial hydatidiform mole, the egg has the mother’s chromosomes, but the father’s chromosomes are also duplicated. Thus, the total number of chromosomes is 69, not 46 as in normal pregnancies. The cause for this condition is due to the entry of two sperm in the egg or, also, the duplication of the chromosomes of the sperm.

What are the risk factors

As much as the hydatidiform mole can develop in any pregnancy, some risk factors can contribute to this:

  • Women living in Mexico, Southeast Asia and the Philippines are more likely to develop hydatidiform mole;
  • White women are at higher risk than black women;
  • Women over 40;
  • Women who have had hydatidiform mole previously;
  • Women with a history of spontaneous abortions.

Symptoms of hydatidiform mole

The symptoms presented in the disease are similar, both in partial and in complete form. However, the symptoms of the partial hydatidiform mole are much milder than those of the complete form. Among these symptoms are:

  • Vaginal bleeding: almost all women have bleeding during pregnancy, but those with hydatidiform mole usually release blood clots or brown discharge.
  • Anemia: when there is too much hemorrhage, the woman’s body cannot replace the red blood cells quickly in terms of loss and this ends up leading the patient to an anemic condition.
  • Abdominal swelling: the uterus and abdomen of a woman with hydatidiform mole increase very sharply after the 6th week of pregnancy.
  • Ovarian cysts: a hormone is produced in excess when the tumor is present, human chorionic gonadotropin (HCG), and it ends up causing fluid-filled cysts formed in the ovaries.
  • Vomiting: almost all pregnancies are accompanied by nausea and vomiting, but in cases of hydatidiform mole, this ends up being more recurrent than normal.
  • Pre-eclampsia: this symptom can occur due to a complication of a normal pregnancy (usually in the third trimester of pregnancy), but when it appears early on, it is necessary to go to a doctor’s appointment as soon as possible. Preeclampsia can present with high blood pressure, headache, exaggerated reflexes, swelling in the hands and feet and loss of protein in the urine.
  • Hyperthyroidism: hyperthyroidism occurs only in women who have a very high level of the HCG hormone and can be characterized with certain symptoms, such as tachycardia, increased skin temperature, sweating, heat intolerance and slight tremors.

Diagnosis and treatment of hydatidiform mole

Many pregnancies affected by hydatidiform mole are diagnosed through the symptoms reported above. However, in order for it to be proven, the doctor who specializes in the disease – who can be either a gynecologist or an obstetrician – can order 3 types of exams:

  • Pelvic examination;
  • Pelvic ultrasound;
  • Blood tests to measure the level of the hormone characteristic of pregnancy.

After the disease is diagnosed, it should be treated by curettage , a procedure done to remove all abnormal tissue from the woman’s uterus. As already explained, because of the hydatidiform mole, pregnancy is unable to go any further, as the fertilized cells do not become a baby.

In some cases, a second curettage is required to remove leftover tissue. After this procedure, the patient must have blood tests every 6 months to monitor the HCG level until it is reset.

Possible complications

After curettage performed on the patient, some complications may develop:

  • Invasive hydatidiform mole: develops from the growth of molar tissue in the muscle layer of the uterus. This tissue can migrate through the bloodstream, reaching organs such as the lung, liver and brain.
  • Persistent gestational trophoblastic disease: as much as it happens in rarer situations, this condition occurs when abnormal cells from the removed tumor remain in the woman’s body. In case of occurrence, it should be treated through chemotherapy.
  • Choriocarcinoma: extremely uncommon, choriocarcinoma is a type of treatable cancer that can be caused either from a hydatidiform or a normal pregnancy or even from a miscarriage.

Emotional shock after a pregnancy with hydatidiform mole

Even if the molar pregnancy does not generate a child, the loss experienced through it is quite significant for a woman. Dreams, plans and hopes are interrupted at once and the patient’s emotional will be undoubtedly shaken. Below, we report some tips on how to deal with this loss:

  • – Grief will be experienced not only by the patient, but also by everyone involved;
  • Comforting phrases may not help, but you have to keep in mind that people, at least, are trying to help;
  • Support and counseling groups can be beneficial in this situation;
  • Make sure you always have a doctor to check if your health is stable due to the disease.


As already mentioned, the hydatidiform mole can develop in any pregnancy, but it is a condition much more observed in women who are under 20 years old or over 40. Therefore, the only way to prevent the disease is through the use of condom during sexual intercourse. If pregnancy is desired, it is necessary that a professional is in contact so that prenatal care is performed in order to prevent not only this condition, but many others.

Many women manage to develop a normal pregnancy after the molar, except that, for this, it is necessary to wait a period for a new pregnancy to be carried out. This period can vary from 6 months, in cases of hydatidiform mole treated without chemotherapy, up to 1 year, in cases of patients who have treated the disease with chemotherapy.

Share this article with your acquaintances! As much as the hydatidiform mole is a rare condition, it can develop in anyone and they need to be informed about the disease.