PRENATAL DIAGNOSIS OF DOWN SYNDROME

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Icon Description automatically generated. Prenatal Testing.

Differences Between Screening and Diagnosis. Population tested Purpose of test Usual method of testing Prerequisite to test Risk of test Screening All women To Select a high risk group Maternal history Maternal biochemistry Maternal virology v/ Ultrasound Diagnostic test should be available Anxiety of a screen positive result Diagnostic Women at high risk To diagnose abnormality Ultrasound Amniocentesis v/ Chorionic villous sampling v/ cordocentesis Patient aware of potential risks Small risk of miscarriage from invasive test.

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First Trimester Second Trimester Third Trimester Ultrasound for fetal nuchal translucency- uses an ultrasound to examine the area at the back of the fetal neck for increased fluid or thickening. AFP screening- it is a protein produced by the fetal liver. It crosses the placenta and enter maternal circulation. Abnormal levels of AFP may indicate a miscalculated due date, as the levels vary throughout pregnancy, defects in the abdominal wall of the fetus, Down syndrome or other chromosomal abnormalities, open neural tube defects, such as spina bifida or multiple pregnancy Ultrasound: show the baby's shape and position in the uterus. Third-trimester ultrasounds can examine the placenta, and sometimes are part of a test called a biophysical profile (BPP) to see whether the baby is getting enough oxygen. Women with high-risk pregnancies may have multiple ultrasounds in their third trimester. Ultrasound for fetal nasal bone determination- nasal bone may not be visualized in some babies with certain chromosome abnormalities, such as Down syndrome. (11- 13 weeks). Estriol. This is a hormone produced by the placenta. It can be measured in maternal blood or urine to be used to determine fetal health. Glucose screening: This test checks for gestational diabetes which can cause health problems for the baby, especially if it is not diagnosed or treated. Pregnancy-associated plasma protein A. A protein produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk of chromosomal abnormality. Inhibin. This is a hormone produced by the placenta Group B Streptococcus culture- (35-37 weeks) GBS bacteria are found naturally in the vaginas of many women but can cause serious infections in newborns. This test involves swabbing the vagina and rectum. A woman whose test comes back positive must go to the hospital as soon as labor begins so that intravenous (IV) antibiotics can be started to help protect the baby from becoming infected..

First Trimester Second Trimester Third Trimester Human chorionic gonadotropin. A hormone produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk of chromosomal abnormality. HCG A nonstress test (NST) is usually done when a health care provider wants to check on the health of the fetus, such as in a high-risk pregnancy or when the due date has passed. The test checks to see if the baby responds normally to stimulation and is getting enough oxygen. A baby that doesn't respond isn't necessarily in danger, but more testing might be needed. If the results of these first trimester screening tests are abnormal, genetic counseling is recommended. Additional testing, such as chorionic villus sampling, amniocentesis, cell-free fetal DNA or other ultrasounds, may be needed for an accurate diagnosis. An ultrasound is used to confirm the milestones of pregnancy and to check the fetal spine and other body parts for defects. Contraction stress test: This test stimulates the uterus with pitocin , a synthetic form of oxytocin (a hormone secreted during childbirth), to determine the effect of contractions on fetal heart rate. It may be recommended when an earlier test indicated a problem and can see whether the baby's heart rate is stable during contractions..

Down Syndrome. This is a condition in which a child is born with an extra copy of their 21st chromosome – hence its other name, trisomy 21..

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Icon Description automatically generated. What is Chorionic Villus Sampling?.

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Icon Description automatically generated. Prior to the Procedure.

Equipment. Transcervical Approach Transabdominal Approach Ultrasound scanner Sterile speculum Iodine preparation 10 cc and 20 cc syringe Transcervical CVS catheter Sample collection container with transport media Ultrasound scanner Sterile drape Chlorhexidine or iodine preparation A local anesthetic (optional) 10 cc and 20 cc syringe 18 gauge or 20 gauge spinal needle Sample collection container with transport media.

During the Procedure (Transcervical Technique). Lithotomy position Insert speculum Apply antiseptic on the cervix/vagina Facilitate passage of the catheter Insert CVS catheter into the placenta guided by US Remove the stylet Attach a 200cc syringe to the catheter Remove tissue sample Remove the catheter.

During the Procedure (Transabdominal Approach). Supine position Apply antiseptic on the abdomen (Apply local anesthetic) Insert needle into the placenta under US guidance Remove the stylet Attach a 20cc syringe to the catheter Remove tissue sample.

After the Procedure. Reassess fetal heart rate + mother’s vital signs. Rho(D) immune globulin maybe given to Rh negative mothers. Send obtained samples to the laboratory for analysis..

Results. Chorionic Villus Sampling Chorionic villus sampling is a prenatal genetic testing that can be offered to women between the 10th and 13th weeks of pregnancy to confirm or rule out that their child has certain genetic conditions. WHAT IT TESTS FOR Chromosomal abnormalities: Down syndrome Edward's syndrome Genetic conditions: Cystic fibrosis Sickle cell anemia RISKS Miscarriage: 1 in 100 pregnancies Rare or mild side effects: • Dizziness • Infection • Abdominal cramps • Rh incompatibility PROCEDURE Consists Of withdrawing a small sample of placental tissue in one of two ways: Transcervical Transabdominal RESULTS Preliminary results are ready in 2-3 days; complete analysis in about 1 0 days CVS is 98-990/0 accurate www.shecares.com.

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DIAGNOSTIC UNCERTAINTY AND MISDIAGNOSIS The false negative rate with CVS is extremely low 0.03 percent in one series of over 62,000 procedures • In contrast, amniocentesis should be performed to rule out a false positive test when the mosaic karyotype is found in mesenchymal cells. • If the chorionic villus sample is inadequate for both direct preparations and long-term cultures, long-term culture appears to be more reliable than a direct preparation.

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Risks and Complications. Chorionic villus sampling carries various risks, including: Miscarriage - risk of miscarriage after chorionic villus sampling is estimated to be 0.22 percent Rh sensitization Infection Inadequate sample.

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Amniocentesis. Icon Description automatically generated.

Icon Description automatically generated. What is Amniocentesis?.

Amniocentesis is a prenatal test. During amniocentesis, an ultrasound transducer is used to show a baby's position in the uterus on a monitor. A sample of amniotic fluid, which contains fetal cells and chemicals produced by the baby, is then withdrawn for testing..

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Audio Recording 27 Apr 2022 at 23:17:32. A fter the amniocentesis procedure, the sample of amniotic fluid will be taken to a laboratory fot testing. T here are two different types of tests: A rapid test A full karyotype test.

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Amniocentesis vs Chorionic Villus Sampling onl.ne WWW.DIFFERENCEBETWEEN.COM Chorionic villus sampling Amniocentesis is a prenatal diagnostic test is a prenatal diagnosti that performs at a low risk test to determine DEFINITION SAMPLE PROCEDURE TEST BLOOD TESTS TIME DMITTING INTO A HOSPITAL RESULT REASON RISK TO BABY AND MOTHER of genetic defects of the fetus. chromosomal or genetie disorders in the fetus. Sample for the amniotic . Sar-rnple of chorionic villus. fluid. Extracts fluid from amnion or amniotic sac and perform the test. C)one through a trans- abdominal process. Required 16-20 weeks stage of pregnancy. Does not require the patient to be adrnitted. 1 Extracts fluid from chorionic villus or the placental tissues and perform the test. Can be done either through the cervix or through the abdornen. Not required 10-12 weeks after the la menstrual cycle. Requires the patient to be admitted at least for 24 hours. Checks DNA. chromosomes and Detects chromosome problems. When the baby has lesser genetic defects. Srnall risk for both mother and baby. chernical markers of t fetus. When the baby has a higher risk of birth defects. Possess a slightly highe risk of miscarriage than the amniocentesis. Furthermore. has a small risk of complications in your baby..

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