Molar pregnancy & GTD (Abdominal mass)

Question 1

What is gestational trophoblastic disease

Answer 1

Group of disorders including complete and partial molar pregnancies and malignant conditions of invasive mole, choriocarcinoma and placental site trophoblastic tumours (PSTT).

Question 2

What is Hydatidiform Mole and molar pregnancy

Answer 2

A benign tumour of the trophoblastic tissue

Molar pregnancy: an abnormal pregnancy where there is overgrowth of the placental trophoblastic tissue

Question 3

What is a complete molar pregnancy

Answer 3

Empty egg fertilised by 2 sperm (or 1 haploid sperm which duplicates DNA)
46 XY or 46 XX (paternal origin only)
Diploid and androgenic
No evidence of foetal tissue

Question 4

What is a partial molar pregnancy

Answer 4

Normal egg fertilised by 2 sperm (or 1 which duplicates DNA)
69 XXX or 69 XXY (1x maternal and 2x paternal origin)
Embryo is not viable as it is triploid
Usually evidence of a foetus or foetal RBCs

Question 5

What is the epidemiology of molar pregnancies

Answer 5

1 in 1000 pregnancies, 1 in 600 therapeutic abortions
15% of complete moles develop into invasive moles
3% of complete moles progress to choriocarcinoma
90% of molar pregnancies are complete moles

Question 6

What are the risk factors for molar pregnancy

Answer 6

Previous molar pregnancies
FHx
Extremes of maternal age (<20, >40)
Ethnicity (Japanese, Asians, native American Indian)
Diet (low beta-carotene, low saturated fat)

Question 7

What are the symptoms of molar pregnancy

Answer 7

Asymptomatic: often seen on scans before symptoms

Painless PV bleeding (i.e. miscarriage)
Hyperemesis (increased βHCG)
Lower abdominal pain or pelvic pain
Symptoms of hyperthyroidism rare (from high bHCG mimicking TSH)
Early-onset pre-eclampsia
Abdominal distension (theca lutein cysts)

Question 8

What are the signs of molar pregnancy on examination

Answer 8

Unusually large uterus for gestational age
Symptoms and signs of pregnancy e.g. anaemia
Acute respiratory failure OR neurological symptoms e.g. seizures – likely to be due to metastatic disease
Thyrotoxicosis (due to high hCG acting on TSHR)

Question 9

What investigations should be done for molar pregnancies

Answer 9

Bedside: urine pregnancy test, urine dipstick
Bloods
- bHCG: grossly elevated, >100,000
- FBC: ?anaemia
- Coagulation screen: greater risk of bleeding during evacuation → risk of DIC
- TFTs: low TSH, T4 high (bHCG mimics TSH)
- Serum metabolic panel
Other
Pelvic US
CXR: look for metastatic disease, alveolar infiltrates (RDS), pulmonary oedema (high output HF, anaemia, hyperthyroidism)
Histological examination: Placental villi with irregular architecture, oedema with true villous cavitation and trophoblast hyperplasia

Question 10

What would be seen on US for molar pregnancy

Answer 10

Complete (easy to see on US)
- Cystic appearance, no embryo or defined gestational sac
- 99.7% diagnosed on USS
- See a ‘snowstorm’- where the vesicles are a lot smaller (lots of small anechoic spaces resembling a bunch of grapes)

Partial (harder to recognise)
- May have an embryo - may initially be viable
- Sometimes a part of the placenta looks cystic but sometimes not
- 50-60% diagnosed
- Often incidentally found on scan
- There will be abnormal uterine enlargement, may demonstrate ovarian cysts

Question 11

What is the management for molar pregnancy

Answer 11

1. Urgent referral to specialist centre
2. Surgical ERPC (Evacuation of Retained Products of Contraception) → Products can be sent for histological diagnosis
3. Monitoring
4. Anti-D prophylaxis
5. Pregnancy test in 3 weeks after management
6. Contraception for the next 12 months, avoid pregnancy for at least 6 months after normal HCG has been achieved

IF hCG >200,000 → chemotherapy

Question 12

What monitoring should be done for molar pregnancies after ERPC

Answer 12

Serial βHCG monitoring in specialist centre
- Rising or stagnant levels → methotrexate
- If continues to rise → ? choriocarcinoma
Do not conceive until follow-up is complete (barrier and COCP)
Avoid IUDs until hCG normalised

Question 13

What are the features of a twin molar pregnancy

Answer 13

One is viable and one molar
If carry on, will have intermittent bleeding
Mother will develop severe early-onset pre-eclampsia
Will have a pre-term delivery
Take home baby rate= 50-55%
Mother will have a lot of close monitoring if she decides to keep the babies and not have a termination

Question 14

What are the complications of molar pregnancy

Answer 14

Progress to malignancy (20% of complex moles, 2% of partial moles)
- Complete mole: invasive mole = 10%; choriocarcinoma = 2.5%
- Partial mole: choriocarcinoma = 0%
Pre-eclampsia
Asherman’s syndrome
Recurrence risk of 1% (≥2 molar pregnancies à recurrence risk 17%)

Question 15

What is the prognosis for molar pregnancy

Answer 15

2-3% develop choriocarcinoma
Invasive = local invasion within the uterus
Gestational trophoblastic neoplasia (ie malignant) = persistent elevation of bHCG e.g. choriocarcinoma, placental site trophoblastic tumour.

Women who receive chemotherapy for gestational trophoblastic neoplasia (GTN) are likely to have an earlier menopause
Women with high-risk GTN using multi-agent chemotherapy (including etoposide) are at increased risk of developing secondary cancers.

Question 16

What is malignant GTD

Answer 16

associated with local invasion or metastasis
1 in 20,000-30,000 pregnancies
Rapidly metastasising (lung, vagina, brain, liver, kidney)
Includes:
- Placental site trophoblastic tumour
- Invasive mole
- Choriocarcinoma

Question 17

Describe placental site trophoblastic tumours

Answer 17

Least common malignancy (<1%)
Benign or malignant neoplasia derived from intermediate trophoblastic cells - intermediate trophoblasts infiltrate myometrium without causing destruction, contains GPL
Local, does not metastasise
Low-level production of beta-hCG
Arises months-years after term pregnancy

Question 18

Describe invasive moles

Answer 18

Moderately common
Invades into the myometrium with venous penetration
Always follows hydatidiform mole
Persistent serum b-hCG levels after evacuation of molar pregnancy
- Plateau in serum b-hCG for 3 consecutive weeks
- Rise in b-hCG of ≥ 10% for at least 3 values over a 2-week period
- +ve b-hCG 6 months after evacuation of a molar pregnancy
Does not metastasise

Question 19

Describe chociocarcinoma

Answer 19

Most common
The malignant transformation of molar tissue or a de novo carcinogenesis that may evolve from an antecedent normal placenta.
Arises from molar pregnancy (50%), previous abortions, normal pregnancy, miscarriage, and ectopic pregnancy (3%)
Presents as dysfunctional vaginal bleeding postnatally that does NOT respond to conventional therapy
Very high hCG= 10,000-100,000 mIU/mL
These are also metastatic

Question 20

What investigations should be done for choriocarcinoma

Answer 20

Histological exam of tissue:
- Presence of both Cytotrophoblasts and Syncytiotrophoblasts
- Chorionic villi are ABSENT (This differentiates the condition from an invasive mole)
Note: metastatic nodules in the vagina should not be biopsied as it is highly vascular

Question 21

What is the treatment for malignant GTD

Answer 21

Manage in specialist centres – CX, Sheffield, Dundee

Placental site trophoblastic tumour: hysterectomy ± chemotherapy
Invasive mole: chemotherapy
Choriocarcinoma: chemotherapy (very responsive)