Diagnosis of gestational trophoblastic disease
Diagnosis is the process of finding out the cause of a health problem. Diagnosing gestational trophoblastic disease (GTD) usually begins when routine pregnancy tests suggest a problem with the pregnancy. Your doctor will ask you about any symptoms you have and may do a physical exam. Based on this information, your doctor may refer you to a specialist or order tests to check for GTD or other health problems.
The process of diagnosis may seem long and frustrating. It’s normal to worry, but try to remember that other health conditions can cause similar symptoms as GTD. It’s important for the healthcare team to rule out other reasons for a health problem before making a diagnosis of GTD.
The following tests are usually used to rule out or diagnose GTD. Many of the same tests used to diagnose GTD are used to find out if the GTD has spread beyond the uterus. Your doctor may also order other tests to check your general health and to help plan your treatment.
Health history and physical exam
Your health history is a record of your symptoms, risk factors and all the medical events and problems you have had in the past. Your doctor will ask questions about your history of:
- symptoms that suggest GTD
- hydatidiform moles
Your doctor may also ask about a family history of GTD.
A physical exam allows your doctor to look for any signs of GTD. During a physical exam, your doctor may:
- do a pelvic exam to check the uterus, vagina, ovaries, fallopian tubes, bladder and rectum for any unusual changes
- feel the abdomen for organs that are larger than normal (such as the liver)
An ultrasound uses high-frequency sound waves to make images of parts of the body. A pelvic ultrasound is a routine test done during pregnancy. A routine ultrasound during pregnancy can often detect GTD.
- If there is a complete hydatidiform mole, the ultrasound will show that there is no fetus.
- If there is a partial mole, the fetus or placenta may not appear normal on an ultrasound.
An ultrasound is usually the first test done if the doctor suspects a gestational trophoblastic tumour. It is used to:
- diagnose the presence of GTD
- look for tissue that remains in the uterus after childbirth
- confirm that there is no new pregnancy
- look for spread to other areas of the pelvis or abdomen
In some cases, an ultrasound probe may be inserted into the vagina (transvaginal ultrasound) to help provide better imaging of pelvic structures.
Find out more about ultrasounds.
Tumour marker tests
Tumour markers are substances found in the blood, tissues or fluids removed from the body. An abnormal amount of a tumour marker may mean that a woman has GTD.
Tumour marker tests are generally used to check your response to cancer treatment. They can also be used to diagnose GTD.
The following tumour markers may be measured for GTD.
Human chorionic gonadotropin (HCG or b-HCG)
Human chorionic gonadotropin (HCG or b-HCG) is the most common tumour marker test used to diagnose GTD. HCG is a hormone that the placenta normally produces during pregnancy. It is the hormone that some pregnancy tests look for. It is not usually found in healthy non-pregnant women.
HCG is usually measured in the blood, but it can also be measured in the urine. HCG levels vary with the type of GTD.
Human placental lactogen (hPL)
Human placental lactogen (hPL) is a tumour marker that may be used to follow women with placental site trophoblastic tumours. It is normally produced by the placenta during pregnancy and may be used to see how well the placenta is working in high-risk pregnancies. hPL is not usually found in non-pregnant women.
Low hPL levels may mean that the placenta and fetus are not developing properly. High hPL levels are found with some types of GTD.
Complete blood count (CBC)
A CBC measures the number and quality of white blood cells, red blood cells and platelets. A CBC is usually done to check for anemia from long-term vaginal bleeding.
Find out more about a complete blood count (CBC).
Dilation and curettage (D&C)
Dilation and curettage (D&C) is a surgical procedure that uses an instrument (curette) to scrape the lining of the uterus to remove abnormal tissue. Many women with GTD are diagnosed during a D&C. A D&C is usually done following a miscarriage or normal pregnancy to remove tissue that can sometimes remain in the uterus.
Examination of the placenta
Following a birth, the placenta is sent to the lab to be examined. Sometimes an unsuspected GTD is found.
Blood chemistry tests
Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs, such as the liver, kidneys and thyroid, are functioning and can help find abnormalities. Higher levels of some substances may mean that GTD has spread to one or more of these organs.
Find out more about blood chemistry tests.
An x-ray uses small doses of radiation to make an image of parts of the body on film. It is used to look for GTD that may have spread to the lungs.
Find out more about x-rays.
A computed tomography (CT) scan uses special x-ray equipment to make 3-D and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.
A CT scan is used to look for GTD that has spread to organs outside the uterus, such as the lungs, brain or liver.
Sometimes a contrast medium is used with a CT scan to help provide better detail. It is usually injected into a vein in the hand or arm.
Find out more about CT scans.
Magnetic resonance imaging (MRI) uses powerful magnetic forces and radiofrequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3-D pictures.
An MRI is rarely done but may be used to look for GTD that has spread to the brain and spinal cord or into the wall of the uterus.
Find out more about MRIs.
A positron emission tomography (PET) scan uses radioactive materials called radiopharmaceuticals to look for changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3-D colour images of the area being scanned.
A PET scan is rarely done but may be used to look for GTD that has spread outside the uterus or has come back after treatment.
Some PET scan machines can perform a CT scan at the same time. This is called PET-CT scanning. A PET-CT scan may sometimes be used to help diagnose or stage GTD.
Find out more about PET scans.
A lumbar puncture (spinal tap) removes a small amount of cerebrospinal fluid (CSF) from the space around the spine to look at it under a microscope. CSF is the fluid that surrounds the brain and spinal cord.
A lumbar puncture can be done to test for HCG if symptoms suggest that GTD has spread to the brain or spinal cord.
Find out more about a lumbar puncture.
Questions to ask your healthcare team
A substance used in some diagnostic procedures to help parts of the body show up better on x-rays or other imaging tests.
In most cases, contrast medium is injected into or around the structure to be examined.
Also called contrast dye or contrast agent.