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Definition
Incidence
Clinical course
Diagnosis
Prognosis
Treatment
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Definition
It is an abnormal pregnancy characterized clinically by abnormalities of the chorionic villi, consisting of varying degrees of trophoblastic proliferation & edema of the villous stroma.
Site: moles usually occupy the uterine cavity; however it may occasionally located in the fallopian tube or even the ovary.
Types:
According to presence or absence of a fetus, or embryo; it may be partial or complete mole.
Differences between complete and partial molar pregnancy:
PARTIAL MOLE MOLE
[A]. Karyotype :69 xxx, or 69 xxy(triploidy)
[B]. Pathology:
1- fetus: Present
2- amnion, fetal RBCs: Present
3- villous edema: Variable, focal
4- trophoblast proliferation: Focal , moderate
[C]. Clinical presentation
1- diagnosis: Missed abortion
2- uterine size: Small for date
3- theca lutein cysts**: Rare
4- medical complications: Rare
5- postmolar disease: 5-10%
COMPLETE MOLE
[A]. Karyotype: 46xx or 46 xy(paternal: androgenesis)*
[B]. Pathology:
1- fetus: Absent
2- amnion, fetal RBCs: absent
3- villous edema : diffuse
4- trophoblast proliferation: diffuse, severe
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* The chromosomes in complete mole are paternal ( androgenesis); the fertilized ovum either contains no chromosomes or inactivated chromosomes.
** Theca lutein cysts are produced by incrased HCG, and may be found also with placental hypertrophy of Rh- isoimmunization, or multiple pregnancy, or even with normal singleton pregnancy. The cysts are variable in size, from few millimeters up to 10 cm.
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Incidence:
- Geography: occurs 1: 1000 in most of the world including the USA. Much increased in certain parts of Asia.
- Age incidence: increased incidence in pregnancies towards the extremes of childbearing period ( <20>40 years).
- Recurrence : 1-2 % of cases of previous moles.
Clinical Features:
Symptoms appear later in the 1st trimester or during 2nd trimester and are more severe with complete mole. These include:
1. Bleeding per vagina: it is the most common symptom. It is of variable amounts. It may be described as 'prune juice ' appearance.
2. Uterine size: large for dates in 50% of cases of complete moles with doughy sensation. May be small for date in partial moles and some cases of complete moles. It may coincide with date in come cases.
3- Fetal activity: FHS not detected although the uterus is above symphysis.
4- Preeclampsia : because Preeclampsia is rarely seen before 24 weeks, if present before that time it suggests molar pregnancy .
5- Hyperemesis gravidarum.
5. Embolisation with trophoblastic tissue with or without villi.
6. Thyrotoxicosis: plasma T4 is elevated may be due to thyrotropin-like action of HCG , or variants TSH produced by molar tissue.
7. Spontaneous expulsion of grape-like vesicles per vagina.
Diagnosis:
Diagnosis is made by the following:
1- Clinical features (vide supra)
2- Ultrasound: very useful in the diagnosis;
(a). Complete mole: picture 'snow storm' or 'honeycomb appearance' with no fetal parts.
(b). Partial mole: picture of missed abortion.
3- Serum β-HCG levels are much higher than expected for the gestational age.
Prognosis:
Maternal mortality: currently mortality from molar pregnancy is reduced to ZERO by more prompt diagnosis and appropriate therapy.
Morbidity:
1. Anemia from bleeding
2. Intrauterine infection and sepsis.
3. Malignant transformation (choriocarcinoma); complete mole (20%), partial mole (4-8%)
Treatment
Treatment of vesicular mole consists of 2 phases;
[A]. Immediate evacuation of molar tissue, and
[B]. Subsequent follow-up for detection of persistent trophoblastic proliferation or malignant transformation.
I. Pre-treatment evaluation:
1. CBC and hemoglobin or hematocrit estimation.
2. Blood transfusion prepared.
3. Searching for metastasis; chest X-ray, if positive(i.e. cannon ball sign), CT chest, liver, brain is indicated.
4. Serum β-HCG estimation to be used as a baseline level for follow-up
5. Medical fitness, and pre-operative assessment .
II. Termination of pregnancy (Evacuation of the mole)
[A]. Vacuum Aspiration; method of choice for evacuation of the hydatidiform mole whatever the uterine size. For large moles, a wide caliber IV line should be established and blood should be ready for transfusion if needed. After complete evacuation of molar tissue, gentle uterine curettage is done. Biopsy from the uterine contents & curettage is sent for histopathology. The procedure may be done under ultrasound guidance. The procedure may be complicated by severe uterine bleeding or uterine perforation.
[B]. Surgical evacuation; using ring forceps and curettage. It is inferior to suction, and may be used in small sized uterus in absence of suction apparatus.
[C]. Oxytocin, Prostaglandins, and Hysterotomy; are no longer used in the management of molar pregnancy.
[D]. Hysterectomy; may be rarely done in certain circumstances;
1. Perforation of the uterus with internal hemorrhage.
2. Age above 40 with sufficient number of children.
III. Prophylactic Chemotherapy:
§ Its role in improving the long term prognosis lacks the evidence.
§ The toxicity from it may be significant including death.
IV. Follow up Procedure:
The prime objective is to early detect malignant changes.
A general method of follow up is as follows;
Contraception for at least ONE year best by COCs (as they suppress LH that cross- react with HCG).
Serum βHCG measurement every 2 weeks.
Once the level is normal (i.e. lower limit of measure for the laboratory) then test βHCG monthly for 6months, then every 2 months for a total of 1 year. Follow up is discontinued and pregnancy allowed after one year.
A rise or persistent plateau in the level requires evaluation & usually therapy.
The following lines of treatment are deferred in the management of molar pregnancy:
Medical evacuation.
Hysterotomy.
Prophylactic chemotherapy
