- Hydatidiform mole is a common complication of gestation, occurring in one of every 1,000- 2,000 pregnancies.
- 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 and 50 years.
- In the classic case of molar pregnancy, quantitative analysis of HCG shows hormone levels in both blood and urine greatly exceeding those produced in a normal pregnancy at the same stage.
- The absence or presence of a fetus or embryo has been used to distinguish complete moles 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.
- Moles rarely coexist with a normal pregnancy, in which a normal fetus and placenta are seen separate from the molar gestation.
- Ninety percent of complete hydatidiform moles have a 46,XX diploid chromosomal pattern. All the chromosomes are derived from the sperm, suggesting fertilization of a single egg that has lost its chromosomes.
- With partial moles, the karyotype is usually triploid (69,XXY): the result of fertilization of a normal egg by two sperm, one bearing a 23,X chromosomal pattern and the other a 23,Y chromosomal pattern.
- 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.
 Imaging Findings
- Complete hydatidiform mole has a classic sonographic appearance of a solid collection of echoes with numerous anechoic spaces (snowstorm appearance).
- In partial moles, the placenta is enlarged and contains areas of multiple, diffuse anechoic lesions.
- A CT scan usually demonstrates a normal-sized uterus with areas of low attenuation, an enlarged inhomogeneous uterus with a central area of low attenuation, or hypoattenuating foci surrounded by highly enhanced areas in the myometrium.
Patient #1: Complete mole
 See Also
 External Links
- CL Green, TL Angtuaco, HR Shah, and TH Parmley. Gestational trophoblastic disease: a spectrum of radiologic diagnosis. RadioGraphics 1996 16: 1371-1384.