Invasive Prenatal Testing involves the insertion of a probe or needle either through the abdominal wall (transabdominal) or the cervix (transcervical) for an examination of the fetus. The procedures are mostly painless and performed under local anaesthesia.

  • Diagnostic amniocentesis
  • Chorionic Villus Sampling
  • Fetal Blood Sampling and Transfusion
  • Therapeutic Amniocentesis or Amnioreduction

The amniocentesis test, also known as amniotic fluid testing, can help provide crucial information about possible abnormalities or disorders in the fetus. While general screenings estimate the risk of chromosomal or genetic conditions in the baby, an amniocentesis test reveals definite information about the potential defects.

Kindly note that amniocentesis isn’t recommended for all parents. Based on your condition, it is advised to evaluate the risks and benefits of the procedure with the help of a medical expert to make a decision about the same. This test is discouraged among mothers with hepatitis B, HIV/AIDS, or hepatitis C by healthcare experts.

The baby in the womb is surrounded by the amniotic sac which carries the amniotic fluid. By testing samples of this fluid, doctors can identify and diagnose the disorders in the fetus.

Some common conditions that can be detected using this test include:

  • Down Syndrome
  • Cystic Fibrosis
  • Sickle Cell disease
  • Tay-Sachs disease
  • Muscular Dystrophy
  • TORCH infection or chorioamnionitis
  • Neural Tube defects
  • Degree of Hemolytic Anemia

The test is also recommended to assess:

Fetal Lung Maturity: This indicates the development of the lungs of the baby. This information can help doctors analyse the maturity of the fetus’s lungs for birth. The fetal lung maturity test is specifically recommended if an early induction or caesarean section is being contemplated. In such conditions, amniocentesis is conducted between the 32nd and 39th week of the pregnancy.

Fetal anaemia: During cases where the baby’s blood cells enter the mother’s bloodstream, the mother’s body produces antibodies. These antibodies might then pass through the placenta and result in damage to the red blood cells of the baby. Comprehended as Rh sensitization, this anaemia can be identified using the amniocentesis test.

Fetal Infection: The test is recommended for babies with a higher risk of infection.

Other reasons why the test may be recommended include:

  • If there were cases of earlier pregnancies or births where chromosomal or neural tube defects were identified.
  • If there is a family history of a singular genetic or birth defects.
  • The mother is older than 35. A higher maternal age increases the risk of chromosomal defects.

The test is generally performed between the 15th and 20th week of pregnancy. An earlier test is usually associated with a higher risk of complications.

  • Miscarriage: The risk of miscarriage is very low and it is estimated to be between 1 -3%.
  • Leak of Amniotic Fluid: In very rare situations, a small amount of amniotic fluid may leak out while the test is conducted. In majority of the cases, the leakage comes to a stop after a week.
  • Vaginal Bleeding: In very rare circumstances

It is recommended that the test is conducted with an empty bladder. A thin needle is inserted through the abdominal wall and into the uterus by the physician. A small volume of fluid is extracted using the needle. This painless procedure might result in a slight cramp during or after inserting the needle.

The results from the amniocentesis test are accurate. Your healthcare provider can guide you through the test results and recommend what has to be done accordingly.

If earlier screenings indicate a high risk of an abnormality, Chorionic Villus Sampling (CVS) is recommended by doctors. This examination will report vital information about the presence of chromosomal or genetic disorders in the baby during pregnancy. This invasive screening procedure involves the testing of small tissue samples from the placenta that surrounds the baby. Conducted between 10 to 14 weeks of pregnancy, CVS is diagnostic of cystic fibrosis, Down Syndrome, or other major chromosomal defects and further related conditions that might be present in the fetus.

CVS Testing is usually conducted through the cervix (transcervical CVS) or the belly (transabdominal CVS).

Doctors will use local anesthesia (anesthesia for the skin) before the procedure. A needle is inserted through the abdomen wall and into the uterus. The needle is carefully observed using an ultrasound scan. A specimen of villi is extracted. The procedure lasts for just a minute.

After the procedure, mothers may have slight abdominal discomfort. Kindly note that these symptoms are quite common and the pregnancy is expected to continue normally. If the pain or bleeding persists, seek advice from your doctor.

  • The risk of miscarriage is estimated to be 1- 3 per thousand.
  • Mothers may notice some spotting or brown discharge a week after the procedure. If spotting persists, it is recommended to use sanitary napkins rather than tampons. Avoid sexual intercourse or swimming until the spotting is cured. Women may also experience mild cramping following the sampling.

The results will usually be available to you between 7 to 14 days of sampling.


Fetal Blood Sampling (FBS), also referred to as cordocentesis or percutaneous umbilical cord blood sampling is the most suitable procedure suggested by doctors when a critical case of fetal anaemia is suspected. The FBS is also used to diagnose Neonatal Alloimmune Thrombocytopenia (NAIT). If recommended before fetal viability (roughly 24 weeks), FBS and intrauterine transfusion are done on an outpatient basis. In cases after fetal viability, mothers will usually be admitted for a few hours in the hospital for the procedure.

The procedure is performed to :

  • Determine the blood type of the fetus
  • Identify fetal anaemia (low red blood count)
  • Identify low platelet count
  • Diagnose possible fetal infections
  • Determine genetic or chromosomal abnormalities

By inserting a needle into the blood circulation of the fetus, doctors collect the necessary samples required for testing. When the extracted blood sample is deficient in either red blood cells or platelets or both, the same needle is then employed to further inject cells in the fetal bloodstream. Anaemia can be detected by maternal parvovirus exposure or infection, the presence of maternal alloantibodies, or other viral infections. Suspected indications from ultrasound findings include fetal hydrops or elevated peak systolic velocity of the fetal middle-cerebral artery by Doppler studies. Other medication can also be injected straight away into the fetal circulation with FBS.

The complete process is done under the effect of local anaesthesia (freezing the skin). Or else, mothers can also opt for intravenous (IV) medication based on their comfort. Under planned circumstances, mothers are required to fast for at least 8 hours prior to the procedure.

The fetus can also receive medication during the procedure to restrict its movement during transfusion. If transfusion takes place after fetal viability, the expecting mother is provided 2 shots of intramuscular steroids in a period of 24 hours. This helps the fetal lungs to mature.

  • A prevalent risk associated with FBS results in bleeding from the puncture site of the umbilical cord. If present, the bleeding is usually self-limited unless thrombocytopenia is also present.
  • Bradycardia is another common complication involved with FBS, although the majority of the cases can be resolved within 5 minutes.
  • Only 1 % of sampling cases have reported fetal loss.

An increased quantity of amniotic fluid in the amniotic sac that surrounds the baby might result in pregnancy-related complications. Termed as polyhydramnios, this condition results in an elevation of amniotic pressure which can cause health problems for both the mother and fetus. With the help of amnioreduction, excessive quantity of fluid can be extracted from the gestational sac.

Through amnioreduction, the normal amniotic fluid volume and pressure can be restored. The extraction of the extra fluid will result in lesser discomfort, better perfusion to the uterus and placenta and aids in lengthening the pregnancy period by decreasing the risk of preterm labour and tear of membranes.

In around 50% of the cases, the exact reason behind polyhydramnios cannot be identified.

  • An increase in fetal glucose levels can be caused by maternal diabetes mellitus. As a result, the fetal urinary output increases and adds to the amniotic fluid causing polyhydramnios.
  • Any abnormality in the fetus, such as neck masses tracheoesophageal fistula, facial cleft, diaphragmatic hernias or neurological or gastrointestinal abnormalities, that impair the baby’s ability to swallow amniotic fluid can also lead to polyhydramnios.
  • Edwards syndrome (Trisomy 18), Down syndrome (Trisomy 21) and other chromosomal defects.
  • Intrauterine infection.
  • Twin-twin transfusion syndrome (TTTS) which affects identical twins which share a single placenta (Monochorionic twins).

Amnioreduction is a simple technical procedure that can be done without the administration of anaesthesia. Using sterile technique under ultrasound guidance, a needle is used to extract the fluid from the sac. Mothers might undergo slight cramp or abdominal uneasiness during the process which will usually subside within a short period of time.

  • Contractions
  • Premature labour
  • Spontaneous premature rupture of membranes
  • Abruption of the placenta that may remain as vaginal bleeding
  • Chorioamnionitis (infection of the fetal membranes)

Seek medical help if you experience any of the following after the procedure

  • Intense contractions
  • Rupture of membranes (water breaking)
  • Vaginal bleeding
  • Fever
  • Reduced fetal movements


Non-Invasive Prenatal Screening analyses DNA samples of the baby to evaluate possible chromosomal conditions during the pregnancy.

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