••• Chapter 50^ Gestational Trophoblastic Disease^495
❍ What is the phantom hCG?
It is a false-positive test result caused by heterophilic antibodies cross-reacting with the hCG test.
❍ When should Phantom hCG be suspected?
When the hCG values plateau at relatively low levels and do not respond to therapeutic maneuvers. Heterophilic
antibodies are not excreted in the urine; therefore urinary hCG values will not be detectable. Also a false-positive
hCG assay will not be affected by serial dilutions of the patient’s sera.
❍ Which form of GTD is less sensitive to chemotherapy?
PSTTs.
❍ How are patients monitored after evacuation of hydatidiform moles?
Ideally, serum hCG should be obtained within 48 hours after evacuation then every week while elevated until
normal for 3 weeks and then monthly until normal for 6 months.
❍ True or False:
- Patients with prior partial or complete moles have a 10-fold increase risk of a second hydatidiform mole
in a subsequent pregnancy.
True. - Pulmonary complications, such as the syndrome of trophoblastic embolization, are frequently observed
around the time of molar evacuation among patients with uterine enlargement of >14 to 16 weeks’
gestational size.
True. - IUD is the encouraged contraceptive during the entire interval of hCG follow-up.
False. In fact they have the potential risk of perforation. - Patients with hCG level >100,000, excessive uterine enlargement, and theca lutein cysts larger than 6 cm
in diameter are at high risk of postmolar persistent tumor.
True. - The diagnosis of vaginal metastasis should be made with biopsy.
False. Vaginal metastasis is present in 30% of patients with metastatic disease. These lesions are highly vascular
and can bleed vigorously if sampled for biopsy.
❍ The diagnosis of postmolar GTD is made when one of the following occurs?
(1) Four values or more of plateauing hCG (+/- 10%) over at least 3 weeks.
(2) Rise of hCG >10% for 3 values or more over at least 2 weeks.
(3) Choriocarcinoma confirmed by histology
(4) Persistence of hCG after 6 months following evacuation of a molar pregnancy.
❍ What pretreatment evaluation is required prior to beginning therapy for GTD?
(1) History and physical examination.
(2) Laboratory evaluation including CBC, serum creatinine, and liver function tests.
(3) Radiographic studies including pelvic ultrasound, CT scan of abdomen and pelvis, chest X-ray or CT of chest,
brain MRI, or CT scan.