1. Gestational Trophoblastic Disease for Undergraduates
Max Brinsmead MB BS PhD
May 2015

2. Gestational Trophoblastic Disease (GTD) is…
A spectrum of disorders in which trophoblastic tissue (usually of pregnancy origin) proliferates abnormally
The spectrum includes:
Hydatidiform mole
Complete and Partial
Invasive mole
Placental site trophoblastic tumour
Choriocarcinoma
Persisting or recurrent disease is better termed Gestational Trophoblastic Neoplasia or GTN

3. Gestational Trophoblastic Neoplasia (GTN) is remarkable because…
There are marked geographical and ethnic differences in its incidence that have
A presumed genetic and
Possibly environmental origins
There are identified chromosomal abnormalities
Has a tumour marker (beta HCG) that is…
highly sensitive and
100% specific (normal pregnancy excluded)
Has very high rates of response to chemotherapy

4. Molar Pregnancies Complete Mole Partial Mole
Diploid chromosomes
No fetal tissue present
Androgenic (paternal) in origin
75% arise from duplication of a monospermic fertilization
25% arise from dispermic fertilization of an “empty ovum”
Partial Mole
90% are triploid and 10% tetraploid or mosaic
Arise when there is dispermic fertilization of a “normal ovum”
Usually have a fetus or some fetal tissue
Chromosome studies and P57 immunochemical histology helps to distinguish the two

5. GTD Incidence and Risk of Malignancy
Incidence of ≈ 1:750 Caucasian pregnancies
≈ 1:400 Asian pregnancies
May be as many as 1:110 pregnancies in SE Asia
10-fold more common when maternal age is >40 years
Complete mole has a 15% risk of GTN
Partial mole has a 0.5% risk of GTN
But only 1:50,000 normal pregnancies go on to GTN

6. Common Presentations of GTD
Bleeding in early pregnancy
“Large for dates” and no fetus or FH found
As an incidental finding during routine early pregnancy ultrasound
Placenta has a “snow-storm” appearance
Partial mole usually diagnosed by histology of failed 1st trimester pregnancy tissue

7. Uncommon Presentations of GTD
Hyperemesis
But most are not GTD
Early onset pre eclampsia (<20w)
Clasically with triploidy i.e. 69 XXY
Thyrotoxicosis
Due to a TSH-effect of abundant HCG
Abdominal distension with theca lutein cysts
Secondary postpartum haemorrhage or ongoing PV bleeding after any pregnancy
But most are not GTN
Seizures (from brain metastases) or haemoptysis (from lung metatases)

8. Management of Molar Pregnancies
Suction curettage preferred over medical evacuation
Because of the risk of trophoblastic embolisation
Cervical ripening with PG’s acceptable
Oxytocin infusion for life threatening haemorrhage
Mole plus a normal twin pregnancy presents dilemmas
Don’t forget the Anti-D if Rh negative

9. Never miss a Mole or GTN by…
Send all “products of conception” for histology
When passed spontaneously
When curetted after failed pregnancy
After curette for secondary postpartum haemorrhage
Not required after termination of pregnancy
When there has been a normal ultrasound before TOP
Or fetal parts are identified
Do a urine test for HCG 3 weeks after all non-surgically managed miscarriage
And no POC for histology
And do a HCG for any abnormal bleeding within 3 months of any pregnancy
Or if the woman presents with a weird tumour

10. Follow up of molar pregnancies:
Monitor for GTN after Complete Mole by…
Weekly HCG until 3 consecutive are negative
Or at 8w if negative before
Then monthly for 6m
No pregnancy please for 6m from time of 1st negative test
For Partial Mole
May stop weekly HCG’s when negative
No pregnancy for 6m please
COC increases the risk of GTN by RR 1.19
Barrier contraceptives best
But only until the HCG returns to normal
And any contraceptive is better than another pregnancy

11. Management of Gestational Trophoblastic Neoplasia
Best done by registering all molar pregnancies with a Specialist Centre
Methotrexate is the 1st line drug but treatment requires individualization
Multi-agent chemotherapy may be required
Second curette rarely necessary
A few patients require surgery (usually hysterectomy) as part of their care

12. Any Questions or Comments?
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