Fluid for Analysis (LDH+Albumin) Fluid Name:

Specimen Required

Fasting Required

Purpose of the Test

To detect and diagnose some birth defects, genetic diseases, and chromosome abnormalities in a foetus, especially if pregnancy screening tests are abnormal; to help diagnose and monitor haemolytic disease in a foetus

When this test is required

While amniocentesis is safe and has been performed for many years, it is an invasive procedure that poses a slight risk of injury to the foetus and of miscarriage. For this reason, it is not performed routinely with each pregnancy.Genetic amniotic fluid testing is offered as part of second trimester prenatal testing and is performed primarily between 15 and 20 weeks gestation if: A woman has a high risk of chromosomal anomaly on a first trimester prenatal screen or second trimester (quad) screening test. A previous child had a chromosome abnormality or birth defect There is a strong family history of a specific genetic disorder A parent has an inherited disorder or both parents have a gene for an inherited disorder An abnormality has been detected on a foetal ultrasoundBiochemical testing is sometimes requested to monitor bilirubin levels when a woman has been sensitised or it is suspected that she has become sensitised (has developed antibodies) to red blood cell antigens and there may be an Rh or other blood type incompatibility with the foetus. In this case, serial testing for bilirubin may be performed, usually about every 14 days.

What the Test Detects

Amniotic fluid surrounds, protects, and nourishes a growing foetus during pregnancy. It allows the baby to move relatively freely, keeps the umbilical cord from being compressed, and helps maintain a stable temperature. Contained within the amniotic sac, amniotic fluid is normally a clear to pale yellow liquid that contains proteins, nutrients, hormones, and antibodies. Amniotic fluid begins forming one to two weeks after…Amniotic fluid surrounds, protects, and nourishes a growing foetus during pregnancy. It allows the baby to move relatively freely, keeps the umbilical cord from being compressed, and helps maintain a stable temperature. Contained within the amniotic sac, amniotic fluid is normally a clear to pale yellow liquid that contains proteins, nutrients, hormones, and antibodies. Amniotic fluid begins forming one to two weeks after conception and increases in volume until there is about 2 pints or 1 litre at 36 weeks of pregnancy. The fluid is absorbed and continually renewed. The foetus swallows and inhales amniotic fluid and releases urine into it. Cells from various parts of the foetus’s body and chemicals produced by the foetus are present in the amniotic fluid. This allows the fluid to be sampled and tested to evaluate foetal health. Amniotic fluid analysis encompasses a range of tests that can be performed to evaluate the health of a foetus. The tests are performed on a sample of amniotic fluid that is obtained through a procedure called amniocentesis. These tests may be performed on samples obtained between 15 and 20 weeks of pregnancy to test for some genetic diseases, chromosome abnormalities such as Down’s syndrome, and neural tube defects. It may also be done when it is suspected that a foetus has a blood type incompatibility with the mother and is at risk for developing haemolytic disease. For genetic testing and chromosome analysis, foetal cells in the amniotic fluid are cultured and grown for several days in the laboratory, then are analysed. Biochemical tests, such as bilirubin and alpha-fetoprotein, and sometimes genetic tests can be performed directly on the amniotic fluid. How is the sample collected for testing? A sample of amniotic fluid is obtained using a procedure called amniocentesis (see Common Questions below). Is any test preparation needed to ensure the quality of the sample? Depending upon the gestational age of the foetus, either a full or empty bladder may be required at the time the amniocentesis is performed. Be sure to follow any instructions that you are given. See MoreSee Less

Preparation for the Test

You may be instructed to have a full or empty bladder prior to amniocentesis

Sample Requirements

A sample of amniotic fluid is obtained using a procedure called amniocentesis

Additional Notes

Both blood contamination and stool from the baby (meconium) in the amniotic fluid can affect some chemical test results.Performed on peripheral blood obtained from the mother, the first trimester screen for Down’s syndrome and the second trimester quad marker screen for Down’s syndrome and open neural tube defects assess the risk of the foetus having these conditions but are not diagnostic. In most cases, the subsequent amniotic fluid tests or ultrasound examination will be normal. Only a small percentage of those with an abnormal blood screening test result will actually have an affected baby.For chromosomal analysis and genetic testing earlier than 15 weeks in a pregnancy, chorionic villus sampling (CVS) can be performed instead of amniocentesis. This first trimester procedure collects a placenta tissue sample at the site of implantation between 11and 13 weeks gestation and carries about the same risk as amniocentesis. CVS cannot, however, detect neural tube defects.

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