Austin Perinatal Associates provides access to any and all available prenatal genetic diagnostic procedures that may be needed during your pregnancy. Preconception consultation is available for those with known genetic disease processes within their families. Prenatal screening and diagnostic testing is available for genetic and chromosomal conditions to all of our patients.
Genetic ScreeningGenetic screening is designed for a patient for no known genetic risk factors for diseases such as cystic fibrosis, fragile X syndrome and spinal-muscular atrophy (SMA). There are currently hundreds of syndromes (many autosomal recessive traits) for which a patient and her partner can be screened.
As with any recessive condition, being a carrier does not mean the baby will get the disease. Only if the mother and father are both carriers is the baby at risk (25% of the time). Further testing may be indicated if one or both parents carry a genetic disease.
Chromosomal ScreeningMany patients believe that chromosomes and genetic screening are the same thing. Actually, while they both involve genetic-type testing, but otherwise they are totally different. Genetic screening and testing are for a specific (frequently single-gene) defects. They are many times inherited from the mother or father or both. Chromosome abnormalities involve entire chromosomal bodies that are either duplicated or absent. You do not have to be a carrier of an abnormal gene to have a chromosomal problem.
The greatest risk for chromosomal problems is a maternal age over 35 years at the time of your due date. The risk is:
- 1:135 at age 35
- 1% at 36
- 2% at age 39
- 2.5% at age 40
As you can see, these risks increase with maternal age.
Screening for some of these common syndromes (such as Down Syndrome, Trisomy 18 and Trisomy 13) can be done by blood tests. Although these exams can be helpful in reducing your risks, they are not diagnostic. Even the most advanced tests (NIPT, cell-free DNA) are only screening exams and are only 95 – 99% accurate. The advantage is that these screening exams are non-invasive and do not have any added risk of miscarriage.
Chorionic Villus Sampling (CVS)Chorionic villus sampling (CVS) is a diagnostic test which involves a needle biopsy of the placenta. This test is usually done between 11 – 14 weeks but may be done later, depending upon your specific needs. The test is done by passing a needle, under ultrasound guidance, into the base of the placenta to remove some of the cells for direct testing and culture.
The test only takes 60 – 90 seconds and is done in Dr. Berry’s office under his expert hands. We use local anesthesia to numb your skin prior to the procedure. Most patients say that a CVS hurts less than having an IV started at the hospital.
Preliminary results are usually back in 48 hours and final results are usually available in 8 calendar days. Dr. Berry’s loss rate from CVS is less than 1 in 500 procedures.
AmniocentesisAlthough considered frightening, an amniocentesis is a simple diagnostic procedure. An amniocentesis is a definitive test for both chromosomes and genetic diseases. This procedure is also done under ultrasound guidance.
A thin needle (smaller in diameter than the one used for common blood draws) is used after local anesthesia of the skin to draw less than one ounce of fluid from the sac surrounding your baby. The procedure usually lasts only 60 seconds and involves a small pinch and a menstrual-like cramp.
Results are usually back and called to the patient within 2 – 8 days. Dr. Berry’s complication rate for miscarriage is less than 1 in 1,000 procedures.