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Understanding Molar Pregnancy: Types Symptoms and Diagnosis

Introduction to Molar Pregnancy

Pregnancy can be an exciting, yet challenging experience for women. Unfortunately, not all pregnancies turn out as we expect them to be.

One such complication that can affect pregnancy is molar pregnancy. Molar pregnancy arises when trophoblasts, which are the cells responsible for forming the placenta, undergo abnormal growth.

This article aims to introduce you to molar pregnancy, its types, and, more specifically, complete mole, its diagnosis, and symptoms.

Definition of Molar Pregnancy

A molar pregnancy, also known as a hydatidiform mole, is a rare condition in which abnormal growth of trophoblasts results in the formation of a mass in the uterus instead of a normal fetus. The uterus then becomes filled with a group of cystic structures that resemble grape-like clusters.

This abnormal growth can occur in both partial and complete mole types of molar pregnancy.

Types of Molar Pregnancy

There are two types of molar pregnancy, complete mole, and partial mole. A complete mole arises from the abnormal fertilization of an egg that has no genetic material, while a partial mole arises from the fertilization of an egg with two sperm.

In a complete mole, there is no fetus inside the uterus as trophoblasts do not give rise to any fetal tissues.

Definition and Characteristics of Complete Mole

A complete mole is a type of molar pregnancy that occurs when an empty egg, without any genetic material from the mother, is fertilized by a single sperm. This fertilization process results in the formation of a mass of cystic structures in the uterus instead of a fetus.

The complete mole is an abnormal placenta that contains no fetal tissue. Due to its unusual characteristics, it is important to diagnose complete mole as early as possible.

Diagnosis and Symptoms of Complete Mole

The onset of a complete mole typically occurs during the first trimester of pregnancy or rarely in the second trimester. The symptoms of a complete mole include vaginal bleeding in early pregnancy, uterine enlargement, pelvis discomfort, severe nausea, vomiting, and high blood pressure.

Although some of these symptoms can occur in normal pregnancies, experiencing these symptoms collectively could indicate a molar pregnancy. Due to the potential risk of the mole developing into a malignancy, accurate and early diagnosis is essential.

The most common way to diagnose a complete mole is through ultrasound imaging and the measurement of serum human chorionic gonadotropin (hCG) levels. Elevated hCG levels and cystic structures in the uterus on ultrasound are strong indications of a complete mole.

Confirmative diagnostic procedures include further interpretation of ultrasound findings and examination of the expelled tissue from the uterus by a pathologist.


Molar pregnancy is a rare complication that can occur during pregnancy, and a complete mole is one of the types of molar pregnancy that requires prompt diagnosis and treatment. Early diagnosis ensures a better prognosis and a successful outcome.

While the symptoms of a complete mole may mimic those of a normal pregnancy, it is vital to consult a medical expert if you experience any of the symptoms discussed in this article. By understanding the definition, characteristics, diagnosis, and symptoms of complete mole, you can make informed decisions about your health during pregnancy.

Partial Mole

In continuation of our discussion on molar pregnancies, we will be delving into partial mole, one of the two types of molar pregnancies. A partial mole occurs when an egg is fertilized by two sperms leading to the development of a mass in the uterus that unlike a complete mole contains fetal tissue, although non-viable, in addition to cystic structures.

Definition and Characteristics of

Partial Mole

A partial mole arises from the fertilization of an egg by two sperm leading to the development of a placenta that is composed of both normal and abnormal trophoblastic cells alongside the non-viable fetus. The partial mole also contains fluid-filled cysts, commonly known as hydropic villi, which can increase in size during pregnancy and develop into cysts that are more complex and can potentially lead to cancer in rare instances.

Similar to a complete mole, a partial mole can also result in high levels of hCG. Causes and Genetic Disorders of

Partial Mole

The primary cause of a partial mole is the random fertilization of an egg with two sets of chromosomes that can occur due to changes in the sperm or the egg.

Unlike a complete mole, fetal tissue can be present in a partial mole, which is generally non-viable, but severe cases may have an embryo that’s partially developed. These non-viable fetuses are susceptible to genetic mutations that lead to rare disorders.

One such rare disorder is Triploidy, in which a fertilized egg contains an unusual amount of chromosomes, 69, instead of the normal 46, resulting in both placental abnormalities and fetal malformations. Similarities between Complete and

Partial Mole

Both complete and partial mole share some similarities.

These similarities include:

Development of cysts:

In both complete and partial mole, cysts form, and these fluid-filled cysts develop into grape-like clusters that can be seen through ultrasound. The cysts are typically larger and more pronounced in partial mole.

No development of fetal tissue:

Both complete and partial mole exhibit no fetal tissue development or have non-viable fetal tissue, meaning there is no fetus structure inside the uterus.


In conclusion, partial mole is another type of molar pregnancy that should be diagnosed early to avoid complications in pregnancy. Partial mole and complete mole share some similarities, but their underlying characteristics and implications differ.

Understanding the genetic disorders related to partial mole can provide insight into potential health risks. Remember to consult your doctor if you suspect you may be experiencing any possible symptoms of molar pregnancy.

Early diagnosis, treatment, and care can greatly improve a successful outcome. Differences between Complete and

Partial Mole

Molar pregnancies are rare and can be either complete mole or partial mole.

Both types have similarities, but they differ in the development of placental tissue, hCG levels, and cysts.

Development of Placental Tissue

The significant difference between complete mole and partial mole lies in the development of placental tissue. In a complete mole, abnormal trophoblastic cells develop rapidly and take over the placenta, resulting in a complete absence of fetal tissue.

This abnormal placental tissue can grow around the fetus, leading to serious complications, such as infection or hemorrhage. In contrast, partial mole has both normal and abnormal trophoblastic cells and, occasionally, fetal tissue, although the latter is non-viable.

HCG Levels

Human chorionic gonadotropin (HCG) levels are an essential indicator for molar pregnancies. Women with a complete mole typically experience significantly higher levels of HCG, which may be 10-50 times higher than levels in normal pregnancies.

This increase in HCG is due to the abnormal growth of trophoblasts in complete mole, which secrete excess HCG. Comparatively, partial mole’s HCG levels remain moderately elevated.

These elevated HCG levels in molar pregnancy may lead to hyperthyroidism, which should be carefully monitored.

Development of Cysts

Cysts play a critical role in both complete and partial mole. In complete mole, the cysts, known as hydropic villi, can be invasive and can penetrate beyond the placenta, posing a risk of cancer.

In contrast, partial mole cysts are non-invasive and usually limited to the placental tissue. Further, partial mole cysts are typically more complex and have a greater risk of developing malignancy than complete mole cysts.


In summary, Molar pregnancy is a rare complication of pregnancy, either complete mole or partial mole. Complete mole develops abnormal trophoblastic cells and no fetal tissues, whereas partial mole develops both abnormal and normal trophoblastic cells alongside non-viable fetal tissues.

The development of placental tissue, HCG levels, and cysts constitute the significant differences between complete and partial mole. High HCG levels point towards a complete mole whereas moderately elevated HCG levels point towards a partial mole.

Further, the cysts associated with complete mole can be invasive and pose a risk of cancer, while partial mole cysts are typically non-invasive but have a higher potential risk of developing malignancy. Early detection, treatment, and support are critical for the successful management of molar pregnancies and can improve outcomes.

Molar pregnancies, which include both complete and partial mole, are rare complications that can occur during pregnancy. Complete mole occurs when there is the abnormal growth of trophoblastic cells, leading to no fetal tissue, while partial mole arises when there is both abnormal and normal trophoblastic cells, with non-viable fetal tissue.

Differences between complete and partial mole include the development of placental tissue, HCG levels, and cysts. Prompt diagnosis, treatment, and care are essential for the management of molar pregnancies.

If you suspect you may have molar pregnancy, consult your doctor immediately. Early detection can significantly improve outcomes.

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