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KEY TERMS

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Key Terms

  1. Complete mole: type of GTD that is characterized by hydropic villi, trophoblastic proliferation, and absence of fetal tissue. The karyotype is usually 46 XX all paternally derived.

  2. Gestational trophoblastic disease: represents a variety of diseases arising from the placenta. The most common is the hydatidiform mole.

  3. Gestational trophoblastic neoplasia: processes that have the capacity for local invasion and/or metastasis, and include invasive moles, gestational choriocarcinomas, and placental site tumors.

  4. Partial mole: a type of gestational trophoblastic neoplasia with fetal tissue or fetal erythrocytes. The karyotype is usually 69 XXX or 69 XXY, of both maternal and paternal origin.

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INTRODUCTION

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Gestational trophoblastic disease (GTD) represents a variety of diseases arising from the placenta. The most common is the hydatidiform mole. Gestational trophoblastic neoplasia (GTN) indicates processes that have the capacity for local invasion and/or metastasis, and include invasive moles, gestational choriocarcinomas, and placental site tumors.1 The incidence of hydatiform moles in the United States is about one 1 in 1000 to 1200 pregnancies. Malignant sequelae after the evacuation of the mole occur in about 20%. Gestational choriocarcinoma occurs in about 1 in 20,000 to 40,000 pregnancies. Although these diseases are not particularly common, women with GTD are seen for pregnancy, or arrive at emergency centers with bleeding, and sonography is almost universally the first imaging test performed.1

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GTDs are a group of disorders that are thought to originate through fertilization of the ovum by 1 or more spermatozoa in either a normal or abnormal manner. This is in contrast to the nongestational forms of choriocarcinoma that can arise in the ovary or testicle and do not involve fertilization or a prior gestational event. The trophoblastic neoplasms arise from the trophoblastic elements of the developing blastocyst, and therefore retain certain inherent characteristics, such as the ability to invade underlying tissues and the ability to synthesize human chorionic gonadotropin (hCG).

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The principal role of sonography in GTD is in establishing the diagnosis of hydatidiform mole.2 A characteristic sonographic appearance of hydropic villi occurs with most molar pregnancies. Sonography is also considered an important adjunctive test to serial β-hCG assays in malignant trophoblastic disease. With sonography, it is sometimes possible to demonstrate uterine invasion by trophoblastic tissue.3 It can also be used to monitor the response of the tumor to therapy, and the presence of other metastatic sites can be ascertained.4 Color Doppler sonography affords detection in areas of abnormal blood flow within the myometrium and can be used as a means to monitor the effectiveness of chemotherapy (Figure 30-1).5

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Figure 30-1.

Color Doppler sonogram (CDS) of partial mole. A: Transvaginal sonogram showing diffuse thickening of placenta with punctuate hypoechoic areas. B: Transabdominal CDS of the same patient as in (A) showing increased flow within molar tissue. C: Transabdominal CDS showing low-impedance, high-diastolic flow within the same areas as (B). ...

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