Hydatidiform moles are one of the most common but benign forms of the gestational trophoblastic disease.
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).
- 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.
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.
The chorionic villi are converted into a mass of clear vesicles that resemble a cluster of grapes.
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.
Please refer to the dedicated articles for discussion on the radiographic features:
Treatment and prognosis
- 1. Fine C, Bundy AL, Berkowitz RS et-al. Sonographic diagnosis of partial hydatidiform mole. Obstet Gynecol. 1989;73 (3 Pt 1): 414-8. - Pubmed citation
- 2. Narlawar RS, Shah J, Patkar D. Images in radiology: complete hydatidiform mole with live pregnancy in a twin gestation. J Postgrad Med. 46 (4): 291-2. J Postgrad Med (link) - Pubmed citation
- 3. Green CL, Angtuaco TL, Shah HR et-al. Gestational trophoblastic disease: a spectrum of radiologic diagnosis. Radiographics. 1996;16 (6): 1371-84. Radiographics (abstract) - Pubmed citation
- 4. Wagner BJ, Woodward PJ, Dickey GE. From the archives of the AFIP. Gestational trophoblastic disease: radiologic-pathologic correlation. Radiographics. 1996;16 (1): 131-48. Radiographics (abstract) - Pubmed citation
- 5. Powell MC, Buckley J, Worthington BS et-al. Magnetic resonance imaging and hydatidiform mole. Br J Radiol. 1986;59 (702): 561-4. doi:10.1259/0007-1285-59-702-561 - Pubmed citation
- 6. Nucci MR, Oliva E. Gynecologic Pathology. Churchill Livingstone. (2009) ISBN:0443069204. Read it at Google Books - Find it at Amazon
Related Radiopaedia articles
- placental anatomy
- placental developmental abnormalities
- placenta previa
- spectrum of abnormal placental villous adherence
- abnormalities of cord insertion
- abruptio placentae
- placental pathology
- vascular pathologies of placenta
- placental infections
- placental masses
- molar pregnancy
- twin placenta