The molar pregnancy: complete and partial mole
There are two types of molar pregnancies: complete or partial. Both types are caused by an egg that is abnormally fertilized. Complete molar pregnancies occur more frequently than partial ones.
A molar pregnancy, also called a hydatidiform mole, is an abnormal growth of tissue that would normally give rise to the placenta.
One of the first indications of a molar pregnancy is vaginal bleeding in the first few weeks of pregnancy. A larger-than-average uterus for gestational age, abdominal pain, and severe nausea may also be present.
The causes are not known even if the age of the woman (under 20 or over 40) can increase the likelihood of situations of this type occurring.
Full wheel and partial wheel
There are two types of molar pregnancies: complete or partial. Both types are caused by an egg that is abnormally fertilized. Complete molar pregnancies occur more frequently than partial ones.
In a complete molar pregnancy , the embryo does not develop while the placental tissue grows rapidly to form an abnormal mass. It usually occurs due to the fertilization of an oocyte that lacks chromosomes or whose chromosomes are inactive, by one or more sperm cells. In this case the fertilized egg contains only the father’s chromosomes. (ultrasound will show the absence of the embryo and the presence of only placental tissue).
In a partial molar pregnancy , a woman releases a normal egg during ovulation but is fertilized by two sperm instead of one.
This leads to an abnormal embryo that contains an excessive number of chromosomes: one set of chromosomes from the mother and two sets of chromosomes from the father, or 69 chromosomes instead of the usual 46 (23 from the mother and 23 from the father). In a partial molar pregnancy, there are too many chromosomes and the embryo cannot develop normally and survive.
Signs and symptoms
Vaginal bleeding is the most common symptom in both types of molar pregnancies. Vaginal bleeding can range from dark brown to light red and usually occurs in the second or third month of pregnancy.
In addition to vaginal bleeding, other signs of a molar pregnancy may include:
- Abnormal growth of the uterus . In the case of full mole, the size of the uterus is larger than the average in the early stages of pregnancy. In the case of partial mole, the size of the uterus is smaller than usual.
- Enlargement of the ovaries . High levels of HCG (human chorionic gonadotropin), a hormone produced during early pregnancy, can make your ovaries larger than usual during pregnancy.
- Severe nausea and vomiting.
- High blood pressure during the first trimester or early second trimester of pregnancy.
The risk factors
Molar pregnancies are quite rare, with one molar pregnancy occurring in every 1,000 pregnancies in the United States.
Factors that increase the likelihood of molar pregnancy occurring:
- Age . Women under the age of 20 or over the age of 40 have a higher risk of experiencing a molar pregnancy.
- Previous molar pregnancy . If a woman has previously had one molar pregnancy then she has a 1-2% higher risk of developing another hydatidiform mole. If a woman has had two previous molar pregnancies then the risk of having another is 15-20% higher than a woman who has never had any.
- Asian ethnicity. Southeast Asian, Vietnamese, and Korean women may have a slightly increased risk of experiencing a molar pregnancy.
The cause
There are currently no clear ideas about the causes . Some have hypothesized that a cause may be represented by the deficiency of carotene, a vegetable pigment present in some red and orange fruits and vegetables. Carotene is transformed by the body into vitamin A.
Diagnosis and testing
Molar pregnancy can be diagnosed by an abdominal ultrasound which can show the presence of cysts in the uterus. A complete molar pregnancy may be easier to spot with ultrasound than a partial molar pregnancy.
If in doubt, the woman is prescribed beta HCG. In women with a complete molar pregnancy , hCG levels may be higher than expected at that stage of pregnancy. The rapidly growing placental tissue stimulates the release of this hormone.
In women with a partial molar pregnancy, HCG levels may be average or slightly elevated, making diagnosis more difficult.
Treatment
Treatment can be pharmacological or surgical. After the scraping, the beta HCG values are usually checked for a few weeks in order to verify their zeroing.
Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.
Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.