Gestational trophoblastic disease (GTD) encompasses a spectrum of diseases arising from abnormal proliferation of trophoblastic tissue. It includes complete hydatidiform mole (hydropic swelling in all villi, no embryonic tissue, 46,XX or 46,XY — entirely paternal), partial hydatidiform mole (focal villous swelling, embryonic tissue may be present, usually triploid 69,XXY), invasive mole, choriocarcinoma, and placental site trophoblastic tumor/epithelioid trophoblastic tumor. Complete mole accounts for 80% of all GTD. Clinically, abnormal uterine bleeding in first trimester, uterus larger than gestational age, and excessively elevated serum β-hCG (>100,000 mIU/mL) are typical. The classic 'snowstorm' appearance and grape-like vesicles on US are diagnostic. MRI is used for myometrial invasion assessment, and CT for metastasis screening. β-hCG monitoring is critically important for treatment response and recurrence surveillance.
Age Range
15-50
Peak Age
28
Gender
Female predominant
Prevalence
Rare
GTD arises from abnormal proliferation of trophoblast cells. In complete mole, fertilization of an empty ovum (nuclear DNA lost) by one or two sperm creates a 46,XX or 46,XY zygote containing entirely paternal genetic material (androgenesis). Absence of maternal genome leads to uncontrolled increase in trophoblastic proliferation — normally maternally imprinted genes (such as p57KIP2) suppress trophoblast growth. Hydropic swelling occurs within villous stroma → cisterns (fluid-filled spaces) form → grape-like vesicles. These vesicles create the 'snowstorm' appearance on US — heterogeneous echogenic pattern from numerous small cystic structures reflecting sound waves. Trophoblast hyperplasia causes excessive β-hCG secretion → theca lutein cysts (bilateral ovaries develop multiple cysts in response to β-hCG stimulation). In invasive mole, trophoblastic tissue invades the myometrium → myometrial invasion and increased vascularity on MRI. In choriocarcinoma, aggressive trophoblastic proliferation shows hematogenous spread (lungs 80%, brain 10%, liver 10%) — hemorrhage is common due to intense neovascularity. On contrast-enhanced MRI, prominent enhancement in tumoral areas — trophoblastic tissue invades spiral arteries creating arteriovenous shunt-like structures.
The signature finding of molar pregnancy is the 'snowstorm' or 'cluster of grapes' appearance in the uterine cavity on US. Numerous small cystic vesicles (hydropic villi) are distributed within heterogeneous echogenic tissue. This finding is most prominent at the end of the first trimester (8-12 weeks). In complete mole, fetal structures are absent; in partial mole, fetal structures may be observed alongside focal vesicles.
On B-mode US, 'snowstorm' appearance in the uterine cavity — numerous small anechoic vesicles within heterogeneous echogenic tissue filling the cavity. In complete mole, vesicles are generally 1-30 mm in diameter, small in early first trimester and enlarging as pregnancy progresses. Fetal echoes are generally absent (complete mole). In partial mole, focal cystic changes with fetal structures may be observed. Tissue filling the cavity appears more echogenic than myometrium with increased vascular flow pattern.
Report Sentence
Numerous small anechoic vesicles within heterogeneous echogenic tissue in the uterine cavity demonstrating 'snowstorm' appearance; this finding is consistent with molar pregnancy (hydatidiform mole).
On Doppler US, trophoblastic tissue shows prominently increased vascularity and low resistance flow pattern. Low RI (<0.4) and increased diastolic flow in uterine arteries are observed. High-velocity, turbulent flow signals are detected within trophoblastic tissue — these findings reflect arteriovenous shunt formation. Myometrial vascular invasion in invasive mole, and more aggressive vascular pattern in choriocarcinoma are observed. Doppler findings are important for early detection of invasive disease and treatment response evaluation.
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Prominently increased vascularity, low resistance index, and turbulent flow pattern within trophoblastic tissue detected on Doppler examination; these findings reflect arteriovenous shunt formation and are consistent with molar pregnancy.
On T2-weighted MRI, numerous T2 hyperintense small vesicular structures in the uterine cavity — 'cluster of grapes' pattern. Vesicles appear bright on T2 due to fluid content. Surrounding trophoblastic tissue shows intermediate T2 signal. MRI better evaluates the degree of myometrial invasion compared to US. In invasive mole, T2 hyperintense areas (trophoblastic invasion) and increased flow voids (vascular invasion) are observed within the myometrium. Disruption of the interface between cavity wall and myometrium indicates invasion.
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Numerous hyperintense vesicular structures in the uterine cavity on T2-weighted MRI demonstrating 'cluster of grapes' pattern; myometrial invasion and increased flow voids are being evaluated.
On contrast-enhanced dynamic MRI, trophoblastic tissue demonstrates prominent and early enhancement. Myometrial invasion areas enhance intensely and appear brighter than normal myometrium. Early venous filling may be observed due to arteriovenous shunt structures. In choriocarcinoma, enhancement is more heterogeneous and aggressive with non-enhancing hemorrhagic areas. Contrast-enhanced MRI is critically important for staging and treatment planning — invasion depth, parametrial extension, and vascular invasion are evaluated.
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Trophoblastic tissue demonstrates prominent early enhancement on contrast-enhanced MRI with intense enhancement in myometrial invasion areas; early venous filling suggests AV shunt formation.
On contrast-enhanced CT, heterogeneously enhancing mass with hypodense cystic areas in the uterus. CT is primarily used for distant metastasis screening in GTD — lung metastases (most common), liver metastases, and retroperitoneal lymphadenopathy are evaluated. Bilateral theca lutein cysts may also be detected on pelvic CT alongside the uterine mass. CT has limited soft tissue contrast for pelvic staging compared to MRI but is the primary modality for thoracic and abdominal metastasis screening.
Report Sentence
Heterogeneously enhancing mass with hypodense cystic areas in the uterus on contrast-enhanced CT accompanied by bilateral theca lutein cysts; thoracic CT for metastasis screening is recommended.
Criteria
Hydropic swelling in all villi, no embryonic tissue, 46,XX or 46,XY (entirely paternal). β-hCG very high (>100,000 mIU/mL). Risk of transformation to malignant GTN 15-20%.
Distinct Features
Classic snowstorm pattern most prominent in this subtype on US. No fetal structures. Theca lutein cysts more frequently accompany. β-hCG very high.
Criteria
Focal villous swelling, embryonic tissue may be present, usually triploid (69,XXY). β-hCG lower. Risk of transformation to malignant GTN 0.5-5%.
Distinct Features
Focal cystic changes with fetal structures or yolk sac may be observed on US. 'Swiss cheese' pattern (focal cystic areas among normal villi). Theca lutein cysts less common.
Criteria
Myometrial invasion (invasive mole) or hematogenous metastasis (choriocarcinoma). β-hCG not declining or rising after evacuation. Staging with FIGO risk score.
Distinct Features
Myometrial invasion, increased flow voids, and prominent enhancement on MRI. Hemorrhage common in choriocarcinoma — T1 hyperintense foci. Lung metastases on chest CT. Chemotherapy (MTX or EMA-CO) is main treatment. Prognosis good — low-risk GTN cure rate >95%.
Distinguishing Feature
Endometrial carcinoma appears as solid mass, does not show cystic vesicles. Occurs in postmenopausal women. β-hCG is not elevated. No snowstorm pattern.
Distinguishing Feature
Submucosal leiomyoma appears as intracavitary solid mass, no cystic vesicles. Typical leiomyoma echo (hypoechoic, posterior shadowing). β-hCG is not elevated. Feeding vessel may be visible on Doppler.
Distinguishing Feature
Hematometra is a homogeneous fluid collection without vesicular structures. T1 hyperintense signal is due to methemoglobin (blood). β-hCG is not elevated. No solid tumoral component in the cavity wall.
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralIn GTD diagnosis, US + β-hCG combination is diagnostic, biopsy is not required. First step in treatment is removal of trophoblastic tissue by suction curettage (uterine evacuation). Serial β-hCG monitoring after evacuation is mandatory — weekly measurement until normal levels, then monthly monitoring (complete mole: 6 months, partial mole: 6 months). β-hCG plateau or rise → malignant GTN (invasive mole or choriocarcinoma) → chemotherapy. Single agent (methotrexate) for low-risk GTN, multi-agent (EMA-CO) for high-risk GTN. Cure rate is excellent (low-risk near 100%, high-risk >90%). Contraception for 6-12 months after evacuation is recommended.
GTD treatment varies by subtype. Suction curettage is performed for complete/partial mole and hCG follow-up is mandatory. Persistently elevated hCG diagnoses gestational trophoblastic neoplasia (GTN). Choriocarcinoma is highly sensitive to chemotherapy — >90% cure rate. MRI is critical for assessing myometrial invasion and vascular involvement.