GTG: Gestational trophoblastic disease Flashcards
What is the most common karyotype in a partial molar pregnancy?
69 chromosomes (90% triploid)
How is a partial mole formed?
Dispermic fertilisation of an empty ovum
What is the karyotype of a complete molar pregnancy?
46 chromosomes (diploid)
How is complete mole formed?
1) dispermic fertilisation of empty ovum
2) duplication of single sperm DNA in an empty ovum
How common is dispermic fertilsation of an empty ovum the cause of a complete mole?
75-80%
Which type of molar pregnancy is more at risk of forming a gestational trophoblastic tumour?
Complete molar pregnancy
What proportion of partial moles will need chemotherapy?
0.5-1%
What proportion of complete moles will need chemotherapy?
13-16%
What is the sensitivity of ultrasound for complete molar pregnancy?
95%
What is the positive predictive value of ultrasound for complete molar pregnancy?
40%
What is the sensitivity of ultrasound for partial molar pregnancy?
20%
What is the positive predictive value of ultrasound for partial molar pregnancy?
22%
What is present in a partial molar pregnancy but not present in a complete molar pregnancy?
Fetal tissue
What is the recommended first line treatment for molar pregnancy?
Dilation and curettage
What is the incidence of molar pregnancy in a subsequent pregnancy?
1%
What is the incidence of developing a gestational trophoblastic neoplasia after a live birth?
rare - 1 in 50,000
What proportion of gestational trophoblastic neoplasias are placental site trophoblastic tumours or epithelioid trophoblastic tumours?
rare = 0.2% of GTN
What is the incidence of gestational trophoblastic disease?
1 in 715
What patient characteristics increase the risk of gestational trophoblastic disease?
<15yo, >50yo, Asian ethnicity
What is the most common presenting symptom for GTD?
vaginal bleeding (60%)
If molar pregnancy is managed medically, how much is the risk of GTN increased?
x16
What proportion of GTD is not diagnosed until after the products have been removed and reviewed in the lab?
2.7%
How long are partial molar pregnancies followed up for?
discharge after x2 normal HCG 4 weeks apart
How long are complete molar pregnancies followed up for?
If HCG normal within 56 days - repeat HCG in 6 months
If HCG abnormal within 56 days, repeat HCG 6 months after a normal HCG level
