What is Gestational Trophoblastic Disease?
Gestational Trophoblastic Disease (GTD) is a condition associated to pregnancy. GTD can be defined as a group of uncommon tumors associated with pregnancy, characterized by abnormal cell growth in the uterus of a woman. These tumors develop from trophoblast (cells) which envelops the embryo. It is different from endometrial and cervical cancers that form from uterine cells. Tumors in GTD are benign as well as malignant, sometimes having the tendency to evade into other organs or tissues.
Gestational Trophoblastic Disease Types
GTD can be classified into the following types:
Picture 1 – Gestational Trophoblastic Disease
Hydatidiform mole (HM) (complete or partial)
This type of GTD is highly common, but generally benign in nature. The condition can be subdivided into partial and complete moles, which are surgically removable.
Placental-site trophoblastic tumor
This is an uncommon type of GTD which may form after an abortion or even a normal pregnancy. It may show invading tendencies and can be surgically removed.
It is identified as a mole which develops in the muscle layer. They may disappear without medical cure, but mostly require treatment. If it causes bleeding, it can be fatal to a woman.
Epithelioid trophoblastic tumor
This rare type of GTD might give rise to diagnostic difficulties. Due to its location in cervix, it can be misdiagnosed as cervical cancer. It usually occurs after a long time of full-term pregnancy.
This is a malignant form of GTD, which has the tendency to grow faster than others, accessing organs located far from uterus. On extremely rare occasions they can even develop without pregnancy.
Gestational Trophoblastic Disease Incidence
It is difficult to assess the occurrence of rare diseases like GTD, as data is insufficient. It usually occurs in women who are of child-bearing age. It is rare in women after menopause. The prevalence of GTD differs largely at various locations in the world. Among 100,000 pregnancies, cases of GTD can be noted to range between 20 and 1300 approximately. Among these, only 10% may be malignant, rest is benign. Geographical variations in incidence of GTD are evident from data which suggests incidence is higher in South America and Asian countries than North America and Europe. The recurrence of GTDs can be almost 1 in 100 cases, mostly when they have considerably increased levels of HCG.
Persistent Trophoblastic Disease (PTD)
PTD is a reference to the molar pregnancies which recur after treatment due to the left over molar tissue. Tumor growth in this case can be treated with success. It has the tendency to spread like malignant cancer but cure is possible. Chemotherapy is the adopted mode of treatment for PTDs.
Gestational Trophoblastic Disease ICD 9 Code
ICD-9 Code of Hydatidiform mole has been ascertained as 236.1, 630.
Gestational Trophoblastic Disease Synonyms
Another name by which GTD is known is called Gestational Trophoblastic Tumour (GTT). When GTD is persistent, it is termed as gestational trophoblastic neoplasia (GTN). A type of GTD, which is known as Hydatidiform mole, is known by the term molar pregnancy.
Gestational Trophoblastic Disease Causes
The exact causes of GTD are not completely known. However, research is being done to determine the process of development of the tumors. Causation of complete and partial moles can be explained by abnormalities found in chromosomes. With the development of GTD, normal process in which a cell multiplies to form a fetus is hampered. The placenta is composed of trophoblasts (cells) which supplies food to the fetus along with elimination of wastes. In GTDs, the placenta is afflicted with abnormal growth of cells, either wholly or partially.
An abnormal egg cell without chromosome may get fertilized by a sperm cell. This is further developed into two identical chromosome copies leading to development of a complete mole instead of a fetus. The absence of chromosome in the egg cannot be explained. A partial mole is formed when a normal egg is fertilized with two sperm cells and the resulting fertilized egg contains 69 instead of 46 chromosomes. An abnormal fetus is formed alongside partial HM.
Gestational Trophoblastic Disease Symptoms
The signs and symptoms of GTD can be enumerated according to the type of the disease that a person is suffering from.
Molar pregnancies (Complete and partial hydatidiform moles)
- Vaginal bleeding is a notable feature, which seems to be comparatively less in partial moles.
- Anemia may result during blood loss happening over a long period of time. It leads to fatigue and breathlessness.
- Frequent vomiting is noted, which surpasses normal vomiting during pregnancy.
- In complete moles, abdomen enlarges due to the abnormal growth of the uterus.
- Pre-eclampsia, which can arise due to complications in normal pregnancy. It is characterized by symptoms like headache, high BP and swelling in the limbs.
- Some women may develop hyperthyroidism due to increase in HCG (Human Chorionic Gonadotropin) levels in blood.
- Ovarian cysts can develop due to excess HCG in some women.
Partial moles cause same symptoms in a less drastic way.
Placental-site trophoblastic tumors (PSTT)
Bleeding in the abdomen is the predominant symptom caused by PSTT, followed by bloating of the abdomen due to uterine enlargement.
Choriocarcinoma and Invasive moles
Know about the symptoms which develop in these invasive cases of GTD:
- Vaginal bleeding, which is common in such cases.
- Enlargement of the abdomen, due to the swelling of the uterus.
- As they are invasive, the tumors may reach up to the vagina causing discharge or bleeding.
- Pain in the pelvic region, fever and discharge from the vagina may be due to infection which is caused at the death of the tumor cells.
- Symptoms like chest pain, blood with coughing, breathing trouble may result due to the spread of GTD into the lungs.
- If it spreads to other organs, headaches, fits, vomiting, jaundice, stomach pain can be caused.
Epithelioid trophoblastic tumors (ETT)
Vaginal bleeding is the common sign. However, other symptoms may also occur if the ETT spreads to the major organs.
Gestational Trophoblastic Disease Diagnosis
During pregnancy, several routine tests are prescribed for a patient. GTD can be detected in any of those tests. Tests which are followed with abortion or miscarriage may also be able to detect GTD. Any abnormality during pregnancy may also hasten the need of diagnostic tests which might diagnose GTD.
Blood tests, urine test and ultrasound are the predominant tools for diagnosis. HCG hormone is usually high in blood or urine samples of pregnant women but abnormal increase in serum HCG might indicate complicated pregnancy. However, in partial moles, ETTs and PSTTs the HCG might not be severely elevated. Blood chemistry tests and blood cell count tests are essential during diagnosis and treatment follow-up in many of the women.
Imaging tests are other parameters for diagnosis of GTDs. Some of these tests are:
- Chest X-Ray
- CT scan
- MRI scan
- Positron emission tomography scans (PET)
Histological findings show correct findings which are performed after delivery of the baby. But biopsy is not performed in cases suspected of malignant GTD. This may lead to a fatal hemorrhage.
Gestational Trophoblastic Disease Treatment
One or multiple treatment options can be ascertained by the physician, after the stage of GTD is determined and diagnosed. GTD is manageable irrespective of the stage or type of it. Treatment will be based on factors like type of GTD, its coverage, time period of its development, HCG levels, metastasis sites (in case it evolves) as well as the exact location of it. Treatment should never be delayed whenever it GTD is diagnosed. Some of the available options for treatment are:
Suction dilation and curettage (D&C), hysterectomy and removal of tumors in other organs are usually performed. With surgery, effective removal of the diseased source is achieved.
It employs anti-cancer drugs administered orally or via injections. It is useful during metastasis. Side effects are usually accompanied with the treatment based on the duration of it and dosage of the drugs.
This is a rare treatment that is only used when poor response is received from patient after chemotherapy. External beam radiation therapy is used mostly for treating painful cancers. With the spread of GTD into the brain, this modality can be opted.
These treatments offer best results when used in conjunction. Yet, they do not always respond to chemotherapy drugs like in most of the GTD types. PSTT is found to be tolerant to chemotherapy drugs unlike other types.
Gestational Trophoblastic Disease Life Expectancy
With GTD, normal life span can be expected if the diagnosis and treatment is done correctly and on time. Timely management can save affected women from varied risks and complications. Close monitoring of beta HCG after treatment ensures good life for patients.
Gestational Trophoblastic Disease Risk Factors
The factors which heighten the risk of getting GTD are:
Picture 2 – Gestational Trophoblastic Disease Image
- Maternal age (women above 35 to 40 years and below 20 years)
- History of being diagnosed with hydatidiform mole previously.
Women below 20 years of age have risks of complete HM but both the groups may be at risk of developing partials HMs. Women who were earlier diagnosed with HM may be 1% vulnerable to HM in the pregnancy which will follow. If HM was more than once, then she is at 25% risk of developing HM again. Women belonging to A blood group are more at risk of developing Choriocarcinoma than those having O blood group.
Gestational Trophoblastic Disease Prognosis
GTD is not life-threatening in the majority of cases. An excellent prognosis can be noted in GTD-afflicted women having Hydatidiform mole. Rare and malignant Choriocarcinoma depicts a great prognosis as it can mostly be cured on early diagnosis. Women having non-metastatic form of the disease can remain fertile and get cured of them. However, in case of metastatic cancers, fertility can be jeopardized irrespective of favorable prognosis. In certain patients with GTN stage IV, poor outcome can be observed. PTDs in most of the patients can be cured even though it may spread. Careful follow-up of women diagnosed with molar pregnancies is done in European countries and is heavily recommended for other nations as well.