FETAL DIAGNOSIS

INTRODUCTION: Several procedures are currently available to determine certain kinds of abnormalities in a fetus or to monitor development.  We should once again remember that the human gestation age goes 40 weeks from the days of the last normal menstruations period.  And although for some people this period may be less or slightly more, the fetus is always monitored with non invasive procedures to make sure that it's life is not in danger and any concerns diagnosed are addressed right away.

ULTRASOUND (OR FETAL ULTRASONOGRAPHY): This is a non-invasive procedure; high-frequency sound waves are transmitted through the abdominal wall into the uterus. The reflected sound waves are converted into an image called a sonogram. This method is used to confirm multiple pregnancies, fetal age or position, or to detect fetal abnormalities such as heart defects or malformations of other organs. Ultrasound may also be used to determine the thickness of the fetal neck, which is an indicator of Down syndrome.

AMNIOCENTESIS: This procedure is usually performed at 16 to 18 weeks of gestation. A hypodermic needle is inserted through the wall of the abdomen into the amniotic sac, and about 10 to 20 mL of amniotic fluid is removed. Within this fluid are fetal cells, which can be cultured so that their chromosomes may be examined. Through such examination and biochemical tests, a number of genetic diseases or chromosome abnormalities may be detected. Because women over the age of 35 years are believed to have a greater chance of having a child with Down syndrome, amniocentesis is often recommended for this age group. A family history of certain genetic diseases is another reason a pregnant woman may wish to have this procedure.

CHORIONIC VILLUS SAMPLING (CVS): In this procedure, a biopsy catheter is inserted through the vagina and cervix to collect a small portion of the chorionic villi. These cells are derived from the fetus but are not part of the fetus itself. The information obtained is the same as that for amniocentesis, but CVS may be performed earlier in pregnancy, at about 8 weeks. Although there is a risk that the procedure may cause a miscarriage, CVS is considered comparable in safety to amniocentesis. It is important to remember that no invasive procedure is without risks.

MATERNAL BLOOD TESTS: Alpha-fetoprotein (AFP) is produced by the fetus and is found in maternal circulation. The level reaches a peak between 12 and 15 weeks of gestation, and should then decrease. If AFP is still high after 16 to 18 weeks, there is a 95% chance that the fetus has spina bifida or anencephaly, malformations of the central nervous system. Maternal blood levels of pregnancy-associated plasma protein A (PAPP-A) and beta hCG can be measured during the first trimester. These tests, in conjunction with ultrasound, can reliably detect Down syndrome.

RELATED;

1. DRUG USE AND PREGNANCY  

2. HEMMOLYTIC DISEASE OF THE NEW BORN

3.  NORMAL LABOR AND VARGINAL DELIVERY

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