Molar Pregnancy and Gestational Trophoblastic Disease - NEET PG OBGYN

Molar pregnancy is an important topic for the NEET PG exam because it is a rare but serious type of gestational trophoblastic disease (GTD) that can have significant implications for the health of the mother and the developing fetus. 

In the NEET PG exam, questions related to molar pregnancy can be included in the obstetrics and gynecology section and can test a candidate's knowledge and ability to diagnose and manage gestational trophoblastic diseases. 

Read this blog further to get a quick overview of this important obstetrics and gynecology topic for NEET PG exam preparation.

Normal Reproduction

Pathogenesis of molar pregnancy  

• Formation of partial mole: If Oocyte is fertilized by 2 sperms  

• Partial Mole
  • Fetus that is partly degenerated by vesicles.
  • It causes Choriocarcinoma in only 2-3% cases (almost not seen)
  • Better prognosis than complete mole.
  • It can also be, 69XXX (mainly), 69XYY, 69 XXY and can never be 69 YYY
• Complete mole

• It can be 46 XX (mainly), 46 XY and can never be 46 YY.
• The degenerated villi formation occurs: Start imbibing fluid and numerous vesicles appear
• There is 20% risk of choriocarcinoma.
• Aborts by itself (12- 16 week) 
• Difference between partial and complete mole

Complete mole	Partial mole
Pathology
Fetal or embryonic tissue	Absent	Present
Hydropic Swelling of villus	Diffuse	Focal
Trophoblastic hyperplasia	Diffuse	Focal
Implantation site trophoblast	Marked atypia	Mild atypia
Karyotype	46 XX (mainly), 46 XY	Triploid (69XXX)

Presentation of complete mole 

• M / C: Bleeding 
• ↑↑ BP 
• Hyperthyroidism as HCG acts similar to TSH
• Rarely passage of grape like vesicles (rare) 
• Uterine size > POG 
• Hyperemesis (due to HCG ↑) 

Also Read: Endometriosis and Adenomyosis - NEET PG OBGYN

Mx of complete mole 

• Any size: Suction / Evacuation, followed by check curettage (after 1 week) because there might be retained bits 
• Chest X-ray because it is M / C site of Mets
• HCG values: Should be followed for at least 6 months after it comes negative 
  • HCG comes negative in 9 weeks: Complete mole 
  • HCG comes negative in 7 weeks: Partial mole 

Important Information  In the follow up period of 6 months, there should not be any pregnancy and we give contraception.

GESTATIONAL TROPHOBLASTIC NEOPLASIA 

• Persistence of Trophoblastic tissue is confirmed by 
  • Continuous bleeding occurs 
  • High HCG >100000 
  • Persistently ↑↑ HCG ± 10% of previous value 
  • Bulky / Enlarged uterus 
• If there is confusion at HPE of Complete Mole or partial Mole: P57 KiP 2 immune staining is done; P57 in immune staining only seen with maternal contribution in the Karyotype, in partial mole
  • Complete mole will not show P57 KiP2 staining. 
• High Risk of Choriocarcinoma is seen with 
  • HCG > 10⁵
  • Very large uterus 
  • Theca Lutein cysts (high HCG) > 6cm size 

• Invasive mole
  • Does not follow normal pregnancy 
  • Marker: HCG 
  • Surgery is mainstay of treatment 
• Choriocarcinoma 
  • Marker: HCG 
  • Chemotherapy is treatment of choice 
  • For older women hysterectomy can be done
• Placental site trophoblastic tumor 
  • Marker: HPL (from cytotrophoblast, and its derivative intermediate trophoblast)
  • Hysterectomy is best management

Choriocarcinoma 

• WHO classification for risk assessment/prognosis

Risk factor	0	1	2	4
Age	= 39	> 39
Antecedent pregnancy	Hydatidiform Mole	Abortion	Term
Interval (months) from antecedent pregnancy	<4	4 to 6	7 to 12	> 12
Human chorionic gonadotropin (HCG) (IU/L)6	<103	-104	-105	>105
ABO blood group (female x male)		0 x A A x 0	AB	B
Largest tumor mass, including uterine (cm)		3-5	>5
Site of Metastases Number of metastases		Spleen 1-4	GI tract 5-8	Brain > 8
Prior chemotherapy			Single drug	Two or more

• WHO classification was used earlier, which includes blood groups also.
• But now it has been replaced by FIGO classification, which says blood group is not considered as a risk factor 
• FIGO Scoring

FIGO Scoring	0	1	2	4
Age (years)	<40	≥40	-	-
Antecedent pregnancy	Mole	Abortion	Term
Interval months from end of index pregnancy to treatment	<4	4 to <7	7 to <13	≥13
Pretreatment serum hCG (IU/l)	< 10 3	10 3 to <10 4	10 4 to <10 5	≥ 105
Largest tumour size, including uterus (cm)	< 3	3 to < 5	≥5	-
Site of metastases	Lung	Spleen, kidney	Gastro intestinal	Liver, brain
Number of metastases		1-4	5-8	>8
Previous failed chemotherapy			Single drug	2 or more drugs

• Low Risk score <7
  • High Risk score ≥ 8
• Staging of trophoblastic Disease (Choriocarcinoma)

Stage	Site of Metastasis	Prognosis	Management
I	Uterus	Good	Single Agent Chemo
II	Pelvis	Based on scoring	if Low score: Single agent chemoIf High score: Multi agent chemo
III	Lung metastasis	Based on scoring	If Low score: Single agent chemoIf High score: Multi agent chemo
IV	Distant Metastasis	Poor	Multi agent chemo is used

• MC site of metastasis is lungs 
• 2^nd MC site of metastasis: Vagina (sub urethral nodule): This appears as a bluish spot in the vaginal area and if you take biopsy of this area, severe hemorrhage can occur, which cannot be controlled by suturing & urgent Radiotherapy needs to be given to control it.

Also Read: Postpartum Hemorrhage: Causes, Types and Management - OBGYN

Previous Year Questions

To study this topic in detail, download the PrepLadder app and get access to engaging video lectures, self-explanatory notes and MCQs covering the topic.