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 

Category:Diseases and disorders of the female reproductive system
Category:Obstetrics and gynecology
Category:Pregnancy and childbirth