Molar pregnancy
Updates to Article Attributes
Hydatidiform moles are one of the most common but benign forms of the gestational trophoblastic disease.
Epidemiology
It is a common complication of gestation, estimated to occur in one of every 1,000-2,000 pregnancies 3. These moles can occur in a pregnant woman of any age, but the rate of occurrence is higher in pregnant women in their teens or between the ages of 40-50 years. There is a relatively increased prevalence in Asia (for example compared with Europe).
Pathology
Subtypes
A hydatidiform mole can either be complete or partial. The absence or presence of a fetus or embryo is used to distinguish the complete from partial moles:
- complete moles are associated with the absence of a fetus
- partial moles usually occur with an abnormal fetus or may even be associated with fetal demise
Rarely, moles co-exist with a normal pregnancy (co-existent molar pregnancy), in which a normal fetus and placenta are seen separate from the molar gestation.
Chromosomal composition
Ninety percent of complete hydatidiform moles have a 46XX diploid chromosomal pattern. All the chromosomes are derived from a single sperm in 90% or less likely two sperms, suggesting fertilization of a single egg that has lost its chromosomes.
With partial moles, the karyotype is usually triploid (69XXY), the result of fertilization of a normal egg by two sperm, one bearing a 23X chromosomal pattern and the other a 23Y chromosomal pattern.
Location
Complete hydatidiform moles usually occupy the uterine cavity and are rarely located in fallopian tubes or ovaries.
The chorionic villi are converted into a mass of clear vesicles that resemble a cluster of grapes.
Markers
In the classic case of molar pregnancy, quantitative analysis of beta-HCG shows hormone levels in both blood and urine greatly exceeding those produced in a normal pregnancy at the same stage.
Radiographic features
Please refer to the dedicated articles for discussion on the radiographic features:
Treatment and prognosis
A complete mole can progress to invasive mole (~15%) or to gestational choriocarcinoma (~7%).
See also
-<p><strong>Hydatidiform moles</strong> are one of the most common but benign forms of <a href="/articles/gestational-trophoblastic-disease">gestational trophoblastic disease</a>. </p><h4>Epidemiology</h4><p>It is a common complication of gestation, estimated to occur in one of every 1,000-2,000 pregnancies <sup>3</sup>. These moles can occur in a pregnant woman of any age, but the rate of occurrence is higher in pregnant women in their teens or between the ages of 40-50 years. There is a relatively increased prevalence in Asia (for example compared with Europe).</p><h4>Pathology</h4><h5>Subtypes</h5><p>A hydatidiform mole can either be <a href="/articles/complete-mole">complete</a> or <a href="/articles/partial-mole">partial</a>. The absence or presence of a fetus or embryo is used to distinguish complete from partial moles:</p><ul>- +<p><strong>Hydatidiform moles</strong> are one of the most common but benign forms of <a href="/articles/gestational-trophoblastic-disease">the gestational trophoblastic disease</a>. </p><h4>Epidemiology</h4><p>It is a common complication of gestation, estimated to occur in one of every 1,000-2,000 pregnancies <sup>3</sup>. These moles can occur in a pregnant woman of any age, but the rate of occurrence is higher in pregnant women in their teens or between the ages of 40-50 years. There is a relatively increased prevalence in Asia (for example compared with Europe).</p><h4>Pathology</h4><h5>Subtypes</h5><p>A hydatidiform mole can either be <a href="/articles/complete-mole">complete</a> or <a href="/articles/partial-mole">partial</a>. The absence or presence of a fetus or embryo is used to distinguish the complete from partial moles:</p><ul>
-</ul><p>Rarely, moles co-exist with a normal pregnancy (<a href="/articles/coexistent-molar-pregnancy">co-existent molar pregnancy</a>), in which a normal fetus and placenta are seen separate from the molar gestation.</p><h5>Chromosomal composition</h5><p>Ninety percent of complete hydatidiform moles have a 46XX diploid chromosomal pattern. All the chromosomes are derived from a single sperm in 90% or less likely two sperms, suggesting fertilization of a single egg that has lost its chromosomes.</p><p>With partial moles, the karyotype is usually triploid (69XXY), the result of fertilization of a normal egg by two sperm, one bearing a 23X chromosomal pattern and the other a 23Y chromosomal pattern.</p><h5>Location</h5><p>Complete hydatidiform moles usually occupy the uterine cavity and are rarely located in <a href="/articles/uterine-tube">fallopian tubes</a> or <a href="/articles/ovaries">ovaries</a>.</p><p>The chorionic villi are converted into a mass of clear vesicles that resemble a <a href="/articles/bunch-of-grapes-sign-disambiguation">cluster of grapes</a>.</p><h5>Markers</h5><p>In the classic case of molar pregnancy, quantitative analysis of <a href="/articles/beta-hcg-1">beta-HCG</a> shows hormone levels in both blood and urine greatly exceeding those produced in a normal pregnancy at the same stage. </p><h4>Radiographic features</h4><p>Please refer to the dedicated articles for discussion on the radiographic features: </p><ul>- +</ul><p>Rarely, moles co-exist with a normal pregnancy (<a href="/articles/coexistent-molar-pregnancy">co-existent molar pregnancy</a>), in which a normal fetus and placenta are seen separate from the molar gestation.</p><h5>Chromosomal composition</h5><p>Ninety percent of complete hydatidiform moles have a 46XX diploid chromosomal pattern. All the chromosomes are derived from a single sperm in 90% or less likely two sperms, suggesting fertilization of a single egg that has lost its chromosomes.</p><p>With partial moles, the karyotype is usually triploid (69XXY), the result of fertilization of a normal egg by two sperm, one bearing a 23X chromosomal pattern and the other a 23Y chromosomal pattern.</p><h5>Location</h5><p>Complete hydatidiform moles usually occupy the uterine cavity and are rarely located in <a href="/articles/uterine-tube">fallopian tubes</a> or <a href="/articles/ovary">ovaries</a>.</p><p>The chorionic villi are converted into a mass of clear vesicles that resemble a <a href="/articles/bunch-of-grapes-sign-disambiguation">cluster of grapes</a>.</p><h5>Markers</h5><p>In the classic case of molar pregnancy, quantitative analysis of <a href="/articles/beta-hcg-1">beta-HCG</a> shows hormone levels in both blood and urine greatly exceeding those produced in a normal pregnancy at the same stage. </p><h4>Radiographic features</h4><p>Please refer to the dedicated articles for discussion on the radiographic features: </p><ul>
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