Pathology in Pregnancy
As everyone will tell you, having a baby is one of life's most amazing and enriching experiences. Whether its your first pregnancy or you've done it all before, pathology tests will play a vital role in your care and progress.
During your pregnancy you'll have many tests. The majority take place in the early weeks to establish an overall picture of your health and make sure there is nothing to compromise your baby's development.
Others occur in the second trimester as your baby is growing and placing more demands on your body. Towards the expected date of delivery, there will be more tests to ensure you and the baby are healthy as you head towards the birth.
Pregnancy tests explained
We understand that not all people will know exactly is meant with each test the doctor refers you for. We have compiled a list of tests that are most commonly referred in pregnancy by midwives and doctors.
Prenatal Health Checks
These are important in giving your doctor or midwife a good overall picture of your health
Reproductive carrier screening: New rebates from 1 November 2023
Medicare-rebated* testing available for three-gene panel (cystic fibrosis, spinal muscular atrophy and fragile X syndrome)
Reproductive Carrier Screening
Reproductive Carrier Screening can identify your risk of having a child with a serious heritable disorder, either prior to conception (preferred) or in early pregnancy. This test is becoming an essential part of pregnancy planning, and allows you to make informed decisions about your reproductive options and prenatal care.
Sonic Genetics has developed an online education course about reproductive carrier screening for women and their reproductive partners. This information will help you have a useful discussion with your doctor about reproductive carrier screening. You can work through the material at your own pace, and go back to review sections if you wish.
First Trimester Screening
The First Trimester blood test looks for down syndrome and other chromosome abnormalities. This screen is most often a combination of a blood test that looks for markers and an ultrasound that investigates the nuchal translucency - the fluid that lies behind your baby's neck.
This test measures the levels of two substances produced by the placenta - pregnancy associates plasma protein (PAPP-A) and human chorionic gonadotropin (hCG). the aim of screening is to determine if there is a chance that your baby has a chromosomal disorder, a definite answer cannot be given without full diagnostic testing.
Non-Invasive Prenatal Test
Sonic Genetics provides non-invasive prenatal testing (or NIPT). This is a blood test that screens for common genetic conditions in the developing fetus.
The test requires a single blood draw, and can be done once you have reached between 10 weeks’ and 13 weeks' gestation. Collecting a maternal blood sample for NIPT poses no threat to the fetus.
Second Trimester Screening
After 15 weeks a different set of blood tests can be performed. As well as assessing the risk of Down syndrome and other chromosome problems, some proteins and hormones can be measured to identify the possible neural tube defects. The second trimester screen measures the blood level of alpha fetoprotein (AFP) which, if elevated, suggests a possible neural tube defect.
It also looks for raised levels of human chorionic gonadotropin (hCG) and unconjugated oestriol (uE3) which suggests possible down syndrome or other chromosome abnormalities. This screening test if often referred to as the 'triple test' because it uses three markers.
The first trimester screen is now considered preferable to the triple test because it more reliably detects Down syndrome. However the time interval for the first trimester screen is short, and the triple test is still valuable if the opportunity fir the earlier screen has passed.
Glucose Tolerance Test
Diabetes during pregnancy (gestational diabetes) is due to the production of placental hormones. These are a normal part of pregnancy but they can reduce the effect of insulin in the body, in some women this can result in elevated blood glucose. As your baby gets bigger, your body has to produce as much as double to three times the amount of insulin.
Gestational diabetes has no real symptoms, but it poses a threat to the baby and increases the chances of birth complications.Therefore, it is important to test for, diagnose and treat. It affects about 10-20% of women and the risk increases with maternal age.
Many doctors screen all women for gestational diabetes, while some will test those who present a higher risk. It is possible you will be asked to have a GTT between 24-26 weeks. This involves a glucose drink and then two blood tests after to test how quickly the glucose is cleared from the blood
Blood Group Test
The blood group test is an important three-in-one test which looks at your particular type of blood.
Blood Group Type: it is important to knwo your blood group type in case you need a transfusion during your pregnancy or the birth. the four blood group types are A, B, AB and O. The most common blood group is type O
Rhesus (Rh) factor and Haemolytic disease of the newborn
The blood group test also identifies your Rhesus factor, which is either positive or negative. This refers to a particular antigen (protein) on the surface of red blood cells. There are a number of antigens but 'D' is the antigen that caused the most problems. About 83% of all humans that are RhD positive and 17% are negative. If your baby has a positive blood group and you have a negative blood group, your immune system can develop antibodies.
The RhD negative parent usually has no problems during their first pregnancy. However after the birth, you can antibodies when a number of the baby's red blood cells leak into your bloodstream. This is most likely to occur at delivery, but it can also happen during pregnancy if the placenta is damaged. about one in six RhD negative people will develop these antibodies.
This can present problems for subsequent pregnancies as babies may be born with anaemia and jaundice, a condition called haemolytic disease of the newborn or Rhesus disease. Injections of Anti-D immunoglobulin will be given at 28 adn 34 weeks to prevent this happening.
RhD immunoglobulin is a sterile solution of antibodies to the RhD factor. It is produced from the Australian Red Cross blood donors. Very strict controls are applied to the selection of donors and to the method of blood processing.
The blood group test also checks for potentially harmful antibodies. With widespread preventative treatment, it is very rare that the screen returns a positive result. If you have received an injection of Anit-D immunoglobulin within the previous six months, the antibody screen can produce a positive result
Newborn screening test
Your baby will have a screening test when they are about three to five days old. A newborn screening test (NBST) may detect certain rare genetic and congenital disorders. The test requires taking a small drop of blood through a heel prick. The tests performed may vary in different states. If the results are positive, a special feeding formula can be introduced.