Molar Pregnancy

• Macroscopically, the chorionic villi are transformed into clusters of vesicles of varying dimensions, resembling a bunch of grapes — hence the name hydatidiform mole.
• Microscopically, complete moles display enlarged, edematous villi and abnormal trophoblastic proliferation, which diffusely involves the entire placenta.
• No fetal tissue or amnion is produced.
• As a result of these changes, the mass of placental tissue completely fills the endometrial cavity.

• Complete mole arises when an empty ovum (with absent or inactivated nucleus) is fertilized by sperm.

Homozygous Form

• Has two identical paternal chromosome complements, derived from duplication of the paternal haploid chromosomes.
• They are always 46, XX and account for 85–90% of complete hydatidiform moles (CHM).
• 46, YY has never been observed.

Heterozygous Form

• Arises when an empty ovum is fertilized by two different sperms (dispermic fertilization).
• The chromosome complement can be 46, XX or 46, XY.
• Accounts for 10–15% of complete moles.
• This diploid set is described as diandric.

Biparental Complete Hydatidiform Mole (CHM)

• Rare condition.
• Both maternal and paternal genes are present.
• Failure of maternal imprinting causes only the paternal genome to be expressed.
• A recurrent form of biparental mole has been described, which is familial and appears to be inherited as an autosomal recessive trait.
• A series of 5 women with as many as 9 consecutive molar pregnancies has also been described.

• An ovum with an active nucleus is fertilized by a duplicated sperm or two haploid sperms.
• Results in a zygote with a triploid set of chromosomes: 69XXY (70%), 69XXX (27%), or 69XYY (3%).
• YYY karyotype has not been observed.
• In addition to placental tissue, partial moles contain fetal tissues and amnion.
• Often associated with the development of an irregularly shaped, nonviable fetus with multiple malformations and abnormal growth.

PHM in Twin and Singleton Pregnancies

• In less than 25% of cases, PHM occurs with the development of an euploid viable fetus.
• Most often presents as a twin pregnancy with one normal fetus and a complete molar pregnancy.
• May also be a twin pregnancy with one normal fetus and an incomplete mole.
• The rarest phenomenon is a singleton pregnancy with a chromosomally normal fetus and a partial molar placenta.

Clinical and Histological Features

• PHM often remains undiagnosed until histologic review of a curettage sample.
• Typically ends in first trimester pregnancy loss as an incomplete or missed abortion.
• Histologically, the degree and extent of villous edema and trophoblastic proliferation are less pronounced than in complete mole.
• Uterine enlargement in excess of gestational age is uncommon.
• β-hCG levels and associated symptoms are less prominent than in complete mole.

Characteristic	Complete Mole (CHM)	Partial Mole (PHM)
Karyotype	Diploid (46, XX, 46, XY)	Triploid (69, XXX, 69, XXY)
Embryo	Absent	Present
Villi Edema	Diffuse (Hydropic)	Focal (Few Hydropic)
Trophoblasts	Diffuse hyperplasia	Mild focal hyperplasia
Implantation-Site Trophoblast	Diffuse atypia	Focal atypia
Fetal RBCs	Absent	Present
β-hCG	High (>50,000)	Slight elevation (<50,000)
Frequency of Classical Symptoms Typical diagnosis Risk of persistent GTT	Common Molar Pregnancy 20–30%	Rare Missed Abortion < 5%
p57Kip2 Immunostaining	Negative	Positive

• Abnormal uterine bleeding
  • Most common symptom – bright red or brownish
  • Occurs in >90% of patients with molar pregnancy
  • Passage of vesicles
• Nausea and vomiting
  • Occurs in 14–32% of patients with hydatidiform mole
  • May be confused with hyperemesis gravidarum
• Previous history of GTD
• Passage of grape-like tissue
• Lower abdominal pain – may be absent in early diagnosis

• General – may be anxious, pale, dehydrated +/- pedal edema
• Signs of thyrotoxicosis may be present
• CVS – tachycardia, BP normal or elevated, hyperactive precordium, signs of heart failure from hyperthyroidism
• Abdomen – doughy uterus; size may be:
  • Large for date in 50% of cases
  • Smaller in 30% of cases
• Pelvic examination
  • Blood smeared vulva
  • Adnexal mass (theca lutein cyst)
  • +/- adnexal tenderness (cyst accident)

• Serum pregnancy test (PT)
• Quantitative serum β-hCG
• FBC + differentials (urgent PCV)
• Coagulation studies
• Liver function test (LFT)
• Electrolytes, Urea, Creatinine (E/U/Cr)
• Urinalysis
• Blood group, Rhesus factor, Group and Crossmatch (GXM)

Imaging and Laboratory Evaluation

• Ultrasound
  • Snowstorm appearance
  • In partial mole: focal trophoblastic changes and fetal tissue may be noted
  • Theca lutein cyst may be seen
• Chest X-ray – baseline film after diagnosis of molar pregnancy
• Histology
• Karyotyping – identifies triploidy

Treatment of CHM

• Resuscitate the patient and treat medical complications before evacuation.
• Treatment should not be delayed—often initiated even before histological confirmation.
• Suction evacuation is the preferred method for hydatidiform mole.
• It is safe, rapid, and effective in nearly all cases.

Preparatory Steps

• Ensure the patient is properly evaluated and fit for surgery.
• Group and crossmatch (GXM) blood.
• Obtain informed consent.
• Prepare (ripen) the cervix using physical dilators or prostaglandins.
• Administer appropriate anaesthesia:
  • General anaesthesia (GA) is preferred.
  • Local anaesthesia (LA) may be used in stable patients with small uterine size.

Suction Evacuation Procedure

• Assemble instruments, scrub, and gown.
• Place the patient in lithotomy position, clean and drape appropriately.
• Empty the bladder.
• Assess uterine size and cervical dilation via bimanual exam.
• Insert Sim’s speculum to expose cervix.
• Grasp cervix with vulsellum and straighten the cervical canal.
• Insert a suction cannula (usually 12–14 mm, smaller than uterine size), should reach just beyond the internal os.
• Connect cannula to suction machine and switch on.
• Start oxytocin infusion toward the end or midway through the procedure.
• Completeness is indicated by a gritty sensation and presence of frothy blood.
• Disconnect suction machine.
• Perform gentle sharp curettage.
• Remove all instruments and ensure haemostasis.
• Clean the patient and reposition.
• Transfer to the recovery room and monitor post-op condition.
• Document findings thoroughly.
• Send tissue samples for histological examination.
• Administer anti-D prophylaxis to Rhesus-negative women after evacuation.
• Rhesus D antigen is expressed on the trophoblast.
• Cervical dilation should admit a 10–12 mm plastic curette.
• Ultrasound-guided suction evacuation is preferred to minimize uterine perforation and confirm completeness.
• Partial mole may require a combination of medical and surgical treatment.
• Oxytocics should not be used prior to evacuation:
  • May be considered in cases of significant haemorrhage.
  • Weigh the risk of oxytocin use against the possibility of tissue embolism.
  • Do not commence oxytocin before evacuation begins.

Complications

• Hemorrhage
  • In cases of large hydatidiform mole (HM) > 12 weeks, a laparotomy setup should be readily available.
  • Hysterotomy or hysterectomy may be necessary in such cases.
• Uterine perforation
  • May occur because the uterus is large and boggy.
  • If perforation is noted, the procedure should be completed under laparoscopic guidance.
• Trophoblastic embolism
  • May cause acute respiratory insufficiency.
  • Avoid oxytocics before onset of uterine evacuation

Hysterectomy

• Rarely recommended, but indicated in:
  • Patients desiring surgical sterilization
  • Women approaching menopause
• Eliminates the risk of local myometrial invasion as a cause of persistent mole.
• Reduces risk of malignant postmolar sequelae to approximately 3–5% compared with 15–20% after suction evacuation.
• Does not eliminate the need for careful follow-up with β-hCG testing.
• Theca lutein cysts may be incidental findings during hysterectomy.
• Adnexa can be preserved bilaterally if cysts are present.
• Surgical treatment is indicated only in cases of:
  • Rupture
  • Torsion
  • Infection
  • Hemorrhage

• The most essential aspect of patient management.
• Incidence of malignant transformation is approximately 20–30%.
• 1–2 weekly serial hCG determinations should begin within 48 hours after evacuation, and continue until three consecutive tests show normal hCG levels (<5 mIU/mL).
• This should be continued weekly until hCG declines to undetectable levels on three successive assays.
• For complete mole:
  • If hCG reverts to normal (<5 IU/mL) within 56 days (8 weeks) of evacuation, follow-up continues for 6 months from the day of evacuation.
  • If hCG does not revert to normal within 56 days, follow-up is for 6 months from the normalization of hCG levels.
• For partial mole, follow-up can be concluded once hCG returns to normal on two samples at least 4 weeks apart.
• Avoid pregnancy during follow-up, ideally until 6 months after the first normal hCG result.
• Oral contraceptives are preferred due to their ability to suppress endogenous luteinizing hormone (LH), which may interfere with hCG measurement.
• Gynaecological exams during follow-up should assess:
  • Uterine size
  • Presence of theca lutein cysts
  • Presence of vulvar, vaginal, or cervical lesions
• Repeat examination at 4-week intervals throughout the observation period.
• Good prognostic signs include:
  • Uterine involution
  • Regression of theca-lutein cysts
  • Cessation of vaginal bleeding