Molar pregnancy

A **molar pregnancy** (also called **hydatidiform mole**) is a rare pregnancy complication. It happens when abnormal tissue grows inside the uterus instead of a normal fetus. This tissue comes from cells that would normally become the placenta.

## What is a molar pregnancy? 
A molar pregnancy is a type of gestational trophoblastic disease. It occurs when there are problems with the genetic material during fertilization. Instead of a normal pregnancy developing, abnormal tissue grows rapidly inside the uterus. This tissue looks like small grape-like clusters.

## Types 
There are two main types of molar pregnancy:

### Complete molar pregnancy 
In a complete molar pregnancy, there is no normal fetus or amniotic sac. This happens when:
* An egg with no genetic material gets fertilized by one or two sperm
* The result is tissue with only the father's genetic material
* All the chromosomes come from the father
* Under ultrasound, it looks like a "snowstorm" pattern
* This type has a higher risk of becoming cancerous

### Partial molar pregnancy 
In a partial molar pregnancy:
* There may be some fetal tissue, but it cannot develop normally
* This happens when a normal egg is fertilized by two sperm
* The fetus has too many chromosomes (69 instead of the normal 46)
* The fetus cannot survive and is usually lost early in pregnancy
* There may be some normal placental tissue mixed with abnormal tissue

## Signs and symptoms 
Early signs of a molar pregnancy are similar to normal pregnancy, but may include:
* Vaginal bleeding during the first 3 months of pregnancy
* Severe nausea and vomiting (worse than normal pregnancy)
* A uterus that grows faster and larger than expected
* Very high levels of hCG hormone in blood tests
* High blood pressure early in pregnancy
* Ovarian cysts caused by high hormone levels
* No fetal heartbeat heard on ultrasound
* Passing grape-like tissue from the vagina

Some women may have no symptoms at first.

## Diagnosis 
Doctors use several tests to diagnose molar pregnancy:
* **Ultrasound examination** - Shows the characteristic "snowstorm" pattern
* **Blood tests** - Measure very high hCG hormone levels
* **Physical examination** - Check uterus size and other symptoms
* **Tissue examination** - If grape-like tissue is passed, it can be tested

Early diagnosis is important for proper treatment and to prevent complications.

## Treatment 
Treatment for molar pregnancy includes:

### Immediate treatment 
* **Suction curettage** - A surgical procedure to remove all abnormal tissue from the uterus
* This is usually done under anesthesia in a hospital
* The removed tissue is examined under a microscope

### Follow-up care 
After treatment, doctors closely monitor patients because:
* hCG hormone levels must return to zero
* Blood tests are done weekly, then monthly for up to one year
* Chest X-rays may be done to check for spread to lungs
* Patients should not get pregnant for at least 6 months to 1 year
* Birth control is strongly recommended during this time

## Complications and risks 
Molar pregnancy can lead to serious complications:

### Immediate risks 
* Heavy bleeding
* High blood pressure
* Anemia from blood loss
* Thyroid problems

### Long-term risks 
* **Persistent gestational trophoblastic disease** - When abnormal cells remain after treatment
* **Choriocarcinoma** - A rare but serious type of cancer that can develop
* Cancer can spread to other parts of the body including:
** Lungs
** Liver
** Brain
** Other organs

This is why long-term follow-up care is very important.

## Prevention and outlook 
### Risk factors 
Some factors that may increase risk include:
* Age under 20 or over 35 years
* Previous molar pregnancy
* Certain ethnic backgrounds
* Diet low in vitamin A and protein

### Outlook 
* Most molar pregnancies are cured with proper treatment
* About 90% of patients have no further problems
* Future normal pregnancies are usually possible
* Early detection and treatment give the best results

## When to see a doctor 
See a doctor right away if you have:
* Heavy vaginal bleeding during pregnancy
* Severe nausea and vomiting
* Passage of grape-like tissue
* No fetal movement when expected
* Very rapid uterus growth

## References 
1. Molar Pregnancy: Early Diagnosis, Clinical Management, and the Central Role of Referral Centers. PMC12346673. 2025. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12346673/
2. Diagnosis and Surgical Treatment of Hydatidiform Mole. PMC12386084. 2025. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12386084/
3. Hydatidiform Mole - StatPearls. NCBI Bookshelf. 2024. Available at: https://www.ncbi.nlm.nih.gov/books/NBK459155/
4. Advances in the diagnosis and early management of gestational trophoblastic disease. PMC9978730. 2022. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC9978730/

## External links