TESTS DURING PREGNANCY

A range of routine tests are recommended during pregnancy to make your pregnancy safe, check and assess the development and well-being of you and your baby, as well as screen for particular conditions.

Other Tests are done only at certain times during pregnancy, or if you have certain indications or problems. Blood tests and urine tests are two routine tests conducted during pregnancy.

Screening tests help to know about a pregnant woman's risk of having a baby with certain birth defects. These are done during the first and second trimesters of pregnancy.

First Trimester Tests (1 - 12 Weeks)

8-10 Weeks

  • Ultrasound on all our patients to help establish your baby's due date and to check on the health of the pregnancy.

  • Blood tests are done to know your blood type (A, B, AB, or O; Rh positive or Rh negative),

  • Immunity to German measles (rubella), and haemoglobin levels.

  • Tests also reveal if you are suffering from conditions such as hepatitis B, syphilis or AIDS.

11-14 Weeks

  • Blood tests to measure papp-A and Bhcg ( these are placental hormones ) together with a Nuchal translucency scan can give the woman a risk ratio of having a baby with Trisomy 21, 18 and 13.

  • Recently there has been some advances in screening and a new test is being used and available in Brisbane, it is called NIPT ( non-invasive prenatal testing ). It involves a simple blood test from you to determine the percentage of fetal cells circulating in your blood. They can then check these fetal cells for genetic abnormalities like trisomy 21, 18 and 13. They can also check the sex of your baby.

Second Trimester Tests (13 - 28 Weeks)

Morphology ultrasound scan is routinely done between 18 to 21 weeks. The baby would have formed all its organs by now and a detailed ultrasound scan would study in detail all organ structure.

The tests of the first and second trimester screenings can be combined to confirm birth defects such as Down syndrome in a relatively larger number (90-95%) of the cases. Positive screening tests are usually followed by diagnostic tests for further information.

Genetic Tests

You will be asked to give a Genetic Testing. Genetic testing is performed to identify changes or abnormalities in the genetic makeup (DNA, chromosomes, genes and proteins) of humans.

The tests can be performed at any stage of life, but is recommended in certain cases before conception, during pregnancy or after birth.

Genetic Tests can help detect

  • Check for the presence of genetic abnormalities in the unborn (embryo or fetus) or newborn

  • Chorionic villus (ability to absorb nutrients from mother) Test for genetic conditions in adults before symptoms surface

  • Check for inheritance or transmission of a certain condition to your family members (carrier testing)

Prenatal genetic studies may be performed during pregnancy to check the genetic makeup of the offspring. In cases of uterine abnormality, you may be recommended for surgery.

Samples for testing can be taken from blood, cheek swabs, and amniotic fluid (protective liquid in which the unborn child develops).

Genetic testing provides vital information for the diagnosis, treatment and prevention of various diseases.

Types of Genetic Tests

  • Molecular genetic testing, used to study short lengths of DNA to identify mutations, chromosomal genetic testing, to study changes in chromosomes like duplication or reduction in number, and

  • Biochemical genetic testing, which is used to study the amount of protein activity. Although genetic testing may give you an insight into the diseases you may develop, it is not always that you will develop a certain condition if your genetic test is positive.

Prenatal Screening and Diagnosis

Prenatal screening tests are safe procedures used to determine if an expectant mother is likely to have a baby with a particular birth defect.

Prenatal tests can include

Cystic Fibrosis

  • Cystic Fibrosis (CF) is a genetically inherited disorder affecting children and young adults. This disorder leads to problems with digestion and respiration, and can shorten the lifespan of an individual. Symptoms of CF include build-up of thick mucus in the lungs causing congestion and associated respiratory problems. Mucus buildup is also seen in the digestive tract leading to difficulty in the absorption of nutrients.

Chorionic Villus Sampling

  • Chorionic villus sampling (CVS): Prenatal test done in weeks 10 and 12 of pregnancy in which a sample of chorionic villus - wispy projections in the placenta (structure that develops in the uterus during pregnancy to provide oxygen and nutrients to the growing baby) is removed and tested to confirm or rule out CF in the baby.

Amniocentesis

  • Amniocentesis: Prenatal procedure in which a sample of amniotic fluid (fluid that surrounds and protects a baby in the uterus) is removed and tested to check if the baby has CF.

Common Risks Associated With Prenatal Testing

Certain risks are common to both the prenatal tests. They include

  • Miscarriage,

  • Rh sensitization (occurs in women with Rh negative blood), and

  • Uterine infection.

Amniocentesis carries additional risks, although rare, such as needle injury, which may occur if the baby moves in the path of the needle used during the procedure.

Also, the baby might develop orthopaedic problems if there is chronic leakage of the amniotic fluid after the procedure.

Fetal Monitoring

Fetal monitoring is the procedure used to assess the rate and rhythm of the fetal heart and determine the foetus’s health. It is generally recommended during late pregnancy and labour.

The average heart rate of the fetus lies between 110 and 160 beats per minute, which can vary up to 5-25 beats per minute. The heart rate may vary as the fetus responds to the uterine conditions, but an abnormal pattern may indicate problems such as the lack of oxygen supplied to the fetus.

Methods

The fetal heart and uterine activity ( CTG ) can be monitored by two methods:

External monitoring: by placement of a device on the mother’s abdomen so that the fetal heartbeat can be heard and recorded. External monitoring can be done to:

  • Track the baby's heart rate during rest and movement

  • Measure the frequency and duration of contractions during labour and delivery

  • Detect premature labour

  • Monitor the baby's health if certain problems are suspected

  • Monitor the placenta (membrane lining the womb and enveloping the fetus) and ensure that the baby gets enough oxygen

  • Monitor for delayed fetal growth, if you have hypertension, diabetes or you have been pregnant for more than 41 weeks

Internal monitoring: placing an electronic device directly on the scalp of the foetus that monitors fetal heart rate. Internal monitoring can be done to:

  • Determine if the baby can be harmed due to stress during labour

  • Measure the duration and strength of labour contractions

External monitoring procedure

External monitoring of the fetal heart can be performed after 25 weeks of pregnancy. The steps include:

  • You will be asked to lie on your back. A clear gel will be applied on your abdomen

  • Dr Alexander will use a Doppler ultrasound device (uses sound waves to create an image of the womb) and move the transducer (sensor) around your abdomen to locate the fetal heartbeat.

  • Continuous electronic monitoring can be done by securing the transducer in place with the help of an elastic belt.

  • The choice of continuous or intermittent monitoring of the fetal heart rate during labour will depend on your condition and the condition of the fetus.

  • The heartbeat can be detected with the help of a Doppler or an electronic monitor.

  • A pattern of the heart rate will be displayed on a computer screen and can be printed.

  • After the procedure is completed, the gel will be wiped off, and you will be allowed to get out of bed.

Internal monitoring during Labour

Internal monitoring procedure is performed only during labour.when needed. The steps include:

  • You will lie on the labour bed with support provided for your feet and legs for a pelvic examination.

  • Dr Alexander will conduct a vaginal examination to check if the cervix has sufficiently dilated.

  • The amniotic sac will then be broken with an instrument, and its contents will flow out through your vagina.

  • Once the doctor determines the head of the fetus with a gloved hand, a plastic electrode will be inserted into your vagina which will guide a spiral wire, which will be placed on the fetal scalp.

  • The wires of the electrode will be held around your thigh with a band and will be connected to the monitor.

  • The electrode will be removed after the birth of the baby.