GESTATIONAL TROPHOBLASTIC NEOPLASIA (GTN)
A 24-year-old Filipino nurse is 14 weeks pregnant by dates. She complains of vaginal bleeding as well as severe nausea and vomiting. Her uterus extends to her umbilicus but no fetal heart tones can be heard. Her blood pressure is 150/95. A dipstick urine shows 2+ proteinuria.
Definition. GTN, or molar pregnancy, is an abnormal proliferation of placental tissue involv-ing both the cytotrophoblast and/or syncytiotrophoblast. It can be benign or malignant. Malignant GTN can be characterized as either localized or metastatic as well as classified into either Good Prognosis or Poor Prognosis.
Classification
• Benign GTN is the classic hydatidiform mole (H-mole). Incidence is 1:1200 in the US,but 1:120 in the Far East.
– Complete mole is the most common benign GTN. It results from fertilization of an empty egg with a single X sperm resulting in paternally derived (androgenetic) normal 46,XX karyotype. No fetus, umbilical cord or amniotic fluid is seen. Theuterus is filled with grape-like vesicles composed of edematous avascular villi. Progression to malignancy is 20%.
– Incomplete mole is the less common benign GTN. It results from fertilization of a normal egg with two sperm resulting in triploid 69,XXY karyotype. A fetus, umbilical cord and amniotic fluid is seen which results ultimately in fetal demise. Progression to malignancy is 10%.
• Malignant GTN is the gestational trophoblastic tumor (GTT) which can develop in3 categories.
– Non-metastatic disease is localized only to the uterus.
– Good Prognosis metastatic disease has distant metastasis with the most common location being the pelvis or lung. Cure rate is >95%.
– Poor Prognosis metastatic disease has distant metastasis with the most common location being the brain or the liver. Other poor prognosis factors are serum b-hCG levels >40,000, >4 months from the antecedent pregnancy, and following a term pregnancy. Cure rate is 65%.
S2 OB-GYN.indb 197
GYN Triad
Molar Pregnancy
• Pregnancy <20 weeks
• HTN and proteinuria
• No fetal heart tones (FHT)
GYN Triad
Molar Pregnancy
• Pregnancy <20 weeks
• HTN and proteinuria
• Vaginal passage of vesicles
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USMLE Step 2 l Gynecology
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Table II-6-1. Benign Gestational Trophoblastic Neoplasia H Mole
| Complete | Incomplete |
| Empty egg | Normal egg |
| Paternal X’s only | Maternal and paternal X’s |
| 46,XX (diploidy) | 69,XXY (triploidy) |
| Fetus absent | Fetus nonviable |
| 20% → malignancy | 10% → malignancy |
No chemotherapy; serial b-hCG titers until (–); follow-up 1 year on oral contraceptive pill
Table II-6-2. Malignant Gestational Trophoblastic Neoplasia
| Nonmetastatic | Good Prognosis | Poor Prognosis |
| Uterus only | Pelvis or lung | Brain or liver |
| 100% cure | >95% cure | 65% cure |
| Single-agent chemotherapy | Multiple agent chemotherapy | |
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| 1 year follow-up on oral contraceptive pill after b-hCG (–) | 5 year follow-up on oral | |
| contraceptive pill | ||
Risk Factors. Increased prevalence geographically is most common in Taiwan and the Philippines. Other risk factors are maternal age extremes (<20 years old, >35 years old) andfolate deficiency.
Clinical Findings
• The most common symptom is bleeding prior to 16 weeks’ gestation and passage ofvesicles from the vagina. Other symptoms of a molar pregnancy include hypertension, hyperthyroidism, and hyperemesis gravidarum, and no fetal heart tones appreciated.
• The most common sign is fundus larger than dates, absence of fetal heart tones, bilateral cystic enlargements of the ovary known as theca-lutein cysts.
• The most common site of distant metastasis is the lungs.
Diagnosis. “Snowstorm” ultrasound. The diagnosis is confirmed with sonogram showinghomogenous intrauterine echoes without a gestational sac or fetal parts.
Management
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• Baseline quantitative b-hCG titer
• Chest X-ray to rule out lung metastasis
• Suction D&C to evacuate the uterine contents
Place the patient on effective contraception (oral contraceptive pills) for the duration of the follow-up period to ensure no confusion between rising b-hCG titers from recurrent disease and normal pregnancy.
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Chapter 6 l Gestational Trophoblastic Neoplasia
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