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 tests normally done to confirm a pregnancy or during pregnancy suggest there is a problem. 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 also used to find out if it has spread beyond the uterus. Your doctor may also order other tests to check your general health and to help plan your treatment.

Your health history is a record of your symptoms, risks and all the medical events and problems you have had in the past. Your doctor may ask questions about:

• symptoms that suggest GTD

• your history of hydatidiform moles

• your 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)

Find out more about physical exams and pelvic exams.

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. It can often find GTD.

• If there is a complete hydatidiform mole, the ultrasound will show that there is no fetus.

• If there is a partial hydatidiform mole, the fetus or placenta may not appear normal on an ultrasound.

An ultrasound is usually the first test done if the doctor suspects GTD. It is used to:

• diagnose the presence of GTD

• look for trophoblastic tissue that remains in the uterus after childbirth, miscarriage or an abortion.

• confirm that there is no new pregnancy

• check if GTD has spread to other areas of the pelvis or abdomen

In some cases, the healthcare team may need to insert an ultrasound probe into the vagina (called transvaginal ultrasound). This is done to get better images of the structures in the pelvis.

Find out more about ultrasounds.

Tumour markers are substances found in blood, tissues or fluids removed from the body. An abnormal amount of a tumour marker may suggest GTD.

Tumour marker tests can be used to diagnose GTD, but they are generally used to check how treatment is working or your response to cancer treatment.

The following tumour markers may be measured for GTD.

Find about more about tumour marker tests.

Human chorionic gonadotropin (hCG or b-hCG) is the most common tumour marker test used to diagnose GTD, monitor how well it responds to treatment and check if it has come back (recurred).

hCG is a hormone that the placenta makes during pregnancy. It is not usually present if you aren’t pregnant. But GTD will cause the body to make hCG. Other health conditions can also cause a high level of hCG.

hCG is usually measured in the blood, but it can also be measured in the urine (pee). hCG levels vary with the type of GTD.

Find out more about human chorionic gonadotropin (hCG or b-hCG).

Human placental lactogen (hPL) is normally made by the placenta during pregnancy. The body doesn’t usually make hPL when you aren’t pregnant.

Doctors may check hPL levels to see if the placenta is developing normally in high-risk pregnancies. Low hPL levels may mean that the placenta and fetus are not developing properly.

High hPL levels are found with some types of GTD, particularly placental site trophoblastic tumour (PSTT).

Talk to your healthcare team about hPL testing and if it is available in your area.

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) is a surgical procedure that uses a suction device and a small spoon-shaped instrument (called a curette) to remove abnormal tissue from the lining of the uterus.

A D&C is usually done after a miscarriage or normal pregnancy to remove placental tissue that can sometimes remain in the uterus. The tissue that was removed is then sent to the lab to check for abnormal cells.

GTD is often diagnosed by a D&C.

Following a birth, the placenta is sent to the lab to be examined. Sometimes GTD is found during this exam.

Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are working and can help find problems.

Sometimes GTD can cause your thyroid to make too much thyroid hormone (called hyperthyroidism). So your healthcare team may do blood tests to check your thyroid levels.

Higher levels of some other substances in the blood may mean that cancerous GTD has spread to the liver or kidneys.

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 3D 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 of the abdomen, pelvis, chest or brain may be done to look at the size of a tumour, to check if lymph nodes are swollen or to see if cancerous GTD has spread to other organs.

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 3D pictures.

In rare cases, an MRI may be used to look for GTD that has spread into the muscle wall of the uterus (called the myometrium) or to the brain.

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 3D colour images of the area being scanned.

In some cases, a PET scan may be used to look for cancerous GTD that has spread outside the uterus or has come back after treatment.

Some PET scan machines can do 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 cancerous GTD.

Find out more about PET scans.

A lumbar puncture (spinal tap) is a procedure used to collect a sample of cerebrospinal fluid (CSF) from the space around the spine. CSF is the fluid that surrounds the brain and spinal cord.

A lumbar puncture may be done if symptoms suggest that cancerous GTD has spread to the brain.

Find out more about a lumbar puncture.

To make the decisions that are right for you, ask your healthcare team questions about a diagnosis.