Gestational trophoblastic diseases (GTD): Causes, signs and symptoms, treatment and prevention

What is Gestational trophoblastic diseases (GTD) ?

These are a condition occurring when there is abnormal development, usually the over-proliferation of the chorionic villi. GTD can either lead to partial or complete hydatidiform mole. There is viable fetus despite the rising of the hCG in the woman’s urine and blood serum.

In other words, GTD is a spectrum of neoplastic disorders originating from placental development. Gestational tissue is present, but the pregnancy is not viable.

How common is Gestational trophoblastic disease

The incident rate is 1:1, 000 pregnancies in United Kingdom but up to 15 times higher in Asian countries.

Types of Gestational trophoblastic diseases

 There are two most common types of GTD namely:

  • Hydatidiform mole (molar pregnancy)
  • Choriocarcinoma.

Risk factors for GTD

  • Race: Women of Asian origin are at higher risk than English women
  • Age: Both teenagers and women over 45 years of age are at higher risk, particularly those women between the age of 18 and 40 years.
  • Previous history of molar pregnancy: women who had suffered GTD have higher risk of the disease recurrent than those without its history.
  • Women with blood group A: those with blood group A tends to have GTD than other group, although the aetiology behind this is not properly known.

Signs and symptoms of GTDs

GTD is a benign condition which usually manifests in second trimester of pregnancy with the following signs and symptoms:

  • Vaginal bleeding
  • A larger than expected uterine size(gestational age)
  • Hyperemesis gravidarum
  • Symptoms of pre-eclampsia often follow

Molar pregnancy/hydatidiform mole

Hydatidiform mole is a benign neoplasm of the chorion in which the chronic villi degenerate and become transparent vesicles containing clear, viscid fluid. 

Pathophysiology: How molar pregnancy develops

Hydatidiform mole is a benign neoplasm of the chorion in which the chronic villi degenerate and become transparent vesicles containing clear, viscid fluid. Hydatidiform mole is classified as complete or partial, distinguished by differences in clinical presentation, pathology, genetics and epidemiology.

The complete mole contains no fetal tissue and develops from an empty egg which is fertilized by a normal sperm. The paternal chromosomes replicate resulting in 46 all paternal chromosomes. The embryo is not viable and dies. No circulation is established and no embryonic tissue is found.

The complete mole is associated with the development of choriocarcinoma. The partial mole has a triploid Karyotype (69 chromosomes), because two sperm have provided a double contribution by fertilizing the ovum.

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Gestational trophoblastic diseases

Types of molar pregnancy/ Hydatidiform mole

Hydatidiform mole is classified as complete or partial, distinguished by differences in clinical presentation, pathology, genetics and epidemiology.

  • The complete mole: This contains no fetal tissue and develops from an empty egg which is fertilized by a normal sperm. The paternal chromosomes replicate resulting in 46 all paternal chromosomes. The embryo is not viable and dies. No circulation is established and no embryonic tissue is found.  The complete mole is associated with the development of choriocarcinoma.
  • The partial mole: This has a triploid Karyotype (69 chromosomes) because two sperm have provided a double contribution by fertilizing the ovum.

What are the differences between complete and partial mole?

Complete molePartial mole
Generalized trophoblastic hyperplasiaFocal trophoblastic hyperplasia
Generalized swelling of villous tissueFocal swelling of villous tissue
No embryonic  or fetal parts Embryonic/fetal part is present
Chromosomal constituent is usually 46, XY or 46, XXChromosomal constituent is usually 69, XXY or    60, XXX
Contains only paternal genomeContains both paternal and maternal genome

Causes of molar pregnancy

The exact cause of molar pregnancy is unknown but researchers are looking into a genetic basis. Studies have revealed some remarkable features about molar pregnancies including:

  • Ability to invade into the wall of the uterus
  • Tendency to reoccur in subsequent pregnancies
  • Possible development into choriocarcinoma, a virulent cancer with metastasis to other organs.
  • Influence of nutritional factors, such as protein deficiency.
  • Tendency to affect older women more often than younger women.

How to diagnose Gestational trophoblastic diseases

Rapid continuous rise in hCG may be a diagnostic clue for GTD which needs to be confirmed by antenatal ultrasound screening. Diagnosis is made through ultrasound revealing appearance of vesicular molar pattern.

Nursing assessment for molar pregnancy

The nurse (midwife) plays a crucial role in identifying this condition and notifying obstetrician. Bases on sound knowledge of clinical manifestation and expertise antenatal assessments, clinical manifestation of GTD is similar to those of spontaneous abortion at about 12 weeks of pregnancy. The following symptoms will alert the midwife about GTD.

  • Presence of early signs of pregnancy such as amenorrhoea, breast tenderness and fatigue.
  • Brownish vaginal bleeding/spotting
  • Anaemia
  • Sever morning sickness due to high levels of hCG.
  • Fluid retention and swelling
  • Uterine size larger than expected for pregnancy dates
  • Very high level of hCG
  • Early development of pre-eclampsia
  • Absence of fetal part, fetal heart rate and fetal activity
  • Expulsion of grapelike vesicles (in some women).
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Management of Gestational trophoblastic diseases

Treatment of molar pregnancy is by both medical and nursing approaches.

Medical treatment for molar pregnancy: Treatment consists of immediate evacuation of uterine content as soon as the diagnosis is made and long-term follows up of the client to detect any remaining trophoblastic tissue that might become malignant.

  • Evacuation of the uterus:

This is then followed by histologic examination of the tissue to enhance accurate diagnosis of molar pregnancy. It is carried out with manual or electrical vacuum aspiration. The tissue obtained is sent for choriocarcinoma.

  • Chemotherapeutic agents:

Women with Rhesus negative factor are highly recommended to receive Anti-D immunoglobulin following a molar pregnancy evacuation.

  • Continuous follow-up care:

This is encouraged until everything stabilizes (hCG being in pregravid state and the woman being fit). Serial levels of hCG help detect residual trophoblastic tissue for 1 year because if any tissue remains, hCG levels will not drop.

In 80% of women with a benign hydatidiform mole, serum hCG titers steadily drop to normal within 8 – 12 weeks after evacuation 20% of women with a malignant hydatidiform mole, serum hCG levels begin to rise. Due to increased risk of cancer, the patient is advised to receive extensive follow-up therapy for the next 12 months.

While in subsequent pregnancies, hCG levels are meticulously monitored for about 6-8weeks of gestation to confirm that molar pregnancy does not occur again. The following-up protocol for GTD include:

  • Baseline hCG level, chest x-ray and pelvic ultrasound.
  • Weekly serum hCG level until it drops to zero and remains at that level for 3 consecutive weeks, then monthly for 6 months, then every 2 months for the remainder of the year.
  • Chest x-ray for every 6 months to detect pulmonary metastasis
  • Regular pelvic examinations to assess uterine and ovarian regression.
  • Systemic assessments for symptoms indicative of lung, brain, liver or vaginal metastasis
  • Strong recommendation to avoid pregnancy for 1 year because the pregnancy can interfere with the monitoring of hCG levels, achievable by use of a reliable contraceptive for at least 1 year.
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Nursing management for molar pregnancy

The aims of nursing management are:

  • Preparing her for uterine evacuation
  • Providing emotional support
  • Educating her about risk that cancer may develop after a molar pregnancy and strict adherence to follow-up

Preparing the client

Once diagnosis is made, immediate evacuation is needed, prepare the client physically and psychologically for the procedure.

Providing emotional support

  • Help the client and family in copying with the loss of pregnancy and possibility of cancer diagnosis.
  • Listen to her concerns and fears
  • Give her time to grieve for pregnancy loss
  • Acknowledge their loss and sad feelings
  • Encourage them to express their grief; allow them to cry
  • Provide them with much factual information as possible to help them understand the situation
  • Arrange for support from additional family and friends with client’s permission/approval.

Educating the client

  • Educate her about the condition and appropriate interventions that may be necessary to save her life.
  • Explain each phase of treatment accurately and provide support for her and her family
  • Inform her about her follow up care which involves close clinical monitoring of the client’s condition for 1 year.
  • Reinforce importance of monitoring her condition.
  • Inform her that serial serum hCG levels are used to detect residual trophoblastic tissue. Continued high hCG is abnormal and need further evaluation
  • Inform her about possible use of chemotherapy, such as methotrexate, which may be given as prophylaxis.
  • Strongly persuade her to use a reliable contraceptive to prevent pregnancy for 1 year as pregnancy will interfere with hCG monitoring.
  • Emphasize the need for client to cooperate and adhere to plan of therapy throughout the year.

Complications of GTD

If the molar pregnancy is not evacuated on time or does not spontaneously miscarry, it can result in these disorders:

  • Gestational trophoblastic neoplasia (GTN): occurring where mole remains in-situ and is diagnosed by continuous rise in hCG and ultrasound scan.
  • Choriocarcinoma: the malignant form of the disease which usually arise from hydatidiform mole
  • Maternal death: the woman may die from sepsis related poorly performed uterine evacuation.

Prevention of Molar pregnancy

There is no specific way of preventing hydatidiform mole. However, women at higher risk of molar pregnancy are encouraged to embrace contraception.

Or if they become pregnancy, the women should endeavour to book for antenatal care on time where ultrasound screening and other supportive investigations would be recommended and performed.