[CG] Gestational trophoblastic disease (molar pregnancy)

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Objectives

This guideline is designed for use within the Early Pregnancy Assessment Service across GGC. The objective is to provide safe management for women with an actual or suspected diagnosis of molar pregnancy. For the purposes of this guideline Molar pregnancy in the first instance refers to pre-malignant molar pregnancies. Malignant pathology may develop later.

Please report any inaccuracies or issues with this guideline using our online form

Incidence in the UK

  • 3:1000 Partial Molar (PHM)
  • 1-3:1000 Complete Molar (CHM)
  • There is a slightly increased risk of molar pregnancy in the very young (<16 years 1.5 x higher incidence) and a significant increase with advanced maternal age (>45 20-50 x higher incidence).
  • The risk of mole is increased by 1-2% following one molar pregnancy and by 15-20% after 2.
  • The risk is not decreased by a change of partner.

Malignant (invasive mole/choriocarcinoma/placental site trophoblastic tumours)

  • The frequency of choriocarcinoma or placental-site trophoblastic tumour is less well known, since these diseases can arise after any type of pregnancy. If suspected, this would require urgent assessment and discussion with Regional Centre.

Please refer to Charing Cross Hospital, Information for Clinicians – https://hmole-chorio.org.uk/info-for-clinicians/

Signs and Symptoms

There are often no signs that a pregnancy is a molar pregnancy. In women with a positive pregnancy test some signs and symptoms in the first or second trimester that may be indicative include -

  • Irregular vaginal bleeding
  • Abdominal pain
  • Hyperemesis
  • Uterus greater than gravid date
  • Early fetal demise
  • Abnormal USS findings

Rarer presentations –

  • Anaemia
  • Excessive uterine enlargement
  • Pre-eclampsia
  • Hyperemesis
  • Hyperthyroidism
  • Respiratory distress

Molar pregnancy may only be suspected/diagnosed at ultrasound examination at 8-14
weeks or found during histological tests carried out after miscarriage.

USS Findings

  • Complete molar pregnancy may show a mass of cells, cystic/orange peel effect/snowstorm effect, without the presence of a foetus
  • Partial molar pregnancy may show an abnormal non-viable foetus and placenta
  • The lack of sonographic molar features does not exclude the possibility of either CHM or PHM.
  • Whenever possible, products of conception from non-viable pregnancies must undergo histological examination to achieve a correct diagnosis regardless of ultrasound findings

MANAGEMENT

Molar evacuation

Suction evacuation is recommended for complete and partial molar pregnancies.

  • Counsel and provide written information
  • Pre-op check FBC, U&E, LFT, TFT’s, G&S and cross match x2units.
  • Inform consultant on-call for gynaecology
  • Arrange surgical evacuation of uterus on a gynaecology list with consultant
  • If >12 weeks(CRL 65mm), discuss management with consultant
  • Molar pregnancy can be associated with excessive bleeding and a consultant should be present throughout the procedure
  • Preparation of the cervix with misoprostol prior to evacuation is thought to be safe.
  • Prolonged use of cervical preparation should be avoided to reduce the risk of embolization of trophoblastic cells.
  • Oxytocin infusion is not recommended prior to completion of the evacuation due to the potential to embolise and disseminate trophoblastic tissue into the venous system. Following completion, if there is ongoing bleeding, consider single dose oxytocin and then follow usual PPH management.
  • All Rh negative women with molar pregnancies (partial or complete) should receive Anti D after evacuation of the uterus.

Combined Molar/Viable pregnancy

Refer to fetal medicine specialist unit

Histopathology and Registration

All women who have had a molar pregnancy enter the surveillance programme.

  • Tissue must be sent to histopathology. Any suspicious tissue will be sent to the Regional Centre in Dundee for confirmation. See contact details below.
  • Request an urgent report
  • Prior to registration patient needs to be forewarned that there is a possibility that she may have a molar pregnancy. This can be done for all losses at time of obtaining SD7’s.
  • Early registration of a confirmed molar pregnancy should take place and the Named Consultant (i.e. the operating consultant) is responsible for this
  • Time taken from surgical evacuation for a definitive diagnosis may be 4 – 5 weeks, but may take longer if extra tests are required

Registration

https://hmole-chorio.org.uk/info-for-clinicians/clinicians_info_registration/

Follow up

All follow up of molar pregnancies will be determined by the Regional Molar Centre on confirmation of diagnosis.

Generally the length of time for HCG to return to normal is less than 8 weeks. However some patients have an elevated but falling hCG level for up to 6 months. Such patients do not require any additional treatment.

It is advised that a further pregnancy is deferred until the end of the follow-up period as a new pregnancy may mask evidence of relapse.

https://hmole-chorio.org.uk/patients_info/

Post-Surgical evacuation advice and Contraception

  • Advise patients that they may have vaginal bleeding for a few weeks postsurgery which should be no heavier than monthly menstruation and should gradually lessen within this time-frame
  • Provide patients with a 24 hour contact number (gynaecology) for worsening symptoms or to attend ED as an emergency if symptoms of heavy vaginal bleeding or severe pain.
  • Practical advice to reduce the chances of bleeding should be given –
    • Avoid sexual intercourse until bleeding has settled
    • Oral contraceptives containing oestrogen and/or progesterone are suitable for use after the evacuation procedure and before the urine hCG result returns to normal.
    • Do NOT use the LNG IUS hormone contraceptive coil immediately post op. However it can be used once the urine or serum hCG has normalised.

Subsequent Pregnancy

  • 1 previous molar pregnancy not requiring chemotherapy - no follow up with hcg tracking required.
  • Two or more molar pregnancies – require registration with Regional Centre, Dundee for postnatal follow up.
  • Chemotherapy treatment required for a molar pregnancy – require registration with Regional Centre, Dundee for postnatal follow up

Contacts/Further Information

Patient information, Charing Cross Hospital (CXH) Trophoblast Disease Service website

Regional Screening Centre for Scotland – Ninewells, Dundee

Hydatidiform Mole Follow-up (Scotland),

Ninewells Hospital and Medical School, Dundee, DD1 9SY.

Tel – 01382 632748
Fax – 01382 496255
Email – [email protected]

UK National Screening Centre – Charing Cross Hospital

Trophoblastic Tumour Screening and Treatment Centre
Department of Medical Oncology
Charing Cross Hospital
Fulham Palace Road
LONDON W6 8RF
UK

http://www.hmole-chorio.org.uk/index.html
Tel: 020 3311 1409
Fax: 020 3313 5577
Email: [email protected]

Last reviewed: 01 January 2021

Next review: 31 January 2026

Author(s): Lynne Thomson

Approved By: Dr R Jamieson, Clinical Director