Overview

Reproductive Genetics at Northwestern Medicine

The Section of Reproductive Genetics within the Division of Clinical Genetics provides genetic counseling, preconception screening, prenatal screening and prenatal diagnosis for a variety of birth defects and genetic disorders. Genetic counseling is also available for infertility and other problems with conception and pregnancy.

To schedule an appointment, please call 312.472.4151.

Care Provided For

Our physicians provide care for many medical conditions including (but not limited to) the following:

• Fetal ultrasound anomalies
• Male factor infertility
• Recurrent pregnancy loss
• Risk to a fetus due to advanced maternal age
• Risk to a fetus due to family history of a genetic disorder

Treatments and Procedures

Our physicians offer a comprehensive array of diagnostic and therapeutic procedures and consultation including:

• Amniocentesis
• Carrier screening (e.g. Tay Sachs)
• Chorionic villus sampling (CVS)
• Chromosome analysis
• DNA analysis
• Genetic counseling for infertility
• Genetic counseling for recurrence risks based on previously affected pregnancies
• Genetic counseling for repeated pregnancy loss
• Percutaneous umbilical blood sampling
• Prenatal screening and diagnosis of birth defects
• Screening for Down syndrome, trisomy 18, and open neural tube defects

Services

The Division of Clinical Genetics provides the most current prenatal screening and diagnostic testing options available to all of our patients. Screening tests and diagnostic tests are two different options for getting more information about the chance that your pregnancy has certain birth defects or genetic disorders. Screening tests are done with ultrasounds, blood tests, or both. Diagnostic tests, sometimes called “invasive” tests, involve inserting a needle or catheter into the area around a developing baby.

The benefits of the screening tests are that they involve no risk to you or your pregnancy for miscarriage and they provide additional information about the chance that your pregnancy has certain birth defects or genetic disorders. The limitations of screening tests are that they will not give you a “yes or no” answer about whether or not your baby has a birth defect and they provide information about only a limited number of birth defects. Screening tests are designed to determine a more accurate risk (or chance) for birth defects, not to diagnose them. Most women who have screening tests use them to help decide if they want to proceed with further diagnostic testing.

The benefits of the diagnostic tests are that they diagnose certain birth defects, giving you a “yes or no” answer, and that they look at more birth defects than screening. The risk of diagnostic tests is that, because they are invasive tests, there is a possibility of miscarriage due to the procedure.

Diagnostic Tests

CVS (chorionic villi sampling)
CVS is a diagnostic test that is performed during the first trimester, from 10 to 14 weeks of pregnancy. The main purpose of CVS is usually to determine whether or not a baby has the normal number of chromosomes. Therefore, CVS is diagnostic for birth defects like Down syndrome, trisomy 18, trisomy 13, and some other chromosome abnormalities. In some situations, CVS can also be used to test for other genetic conditions that your baby may be at risk for based on family history or carrier screening results. CVS is generally performed in one of two ways, either by inserting a needle through a mother’s abdomen or a catheter through the cervix into a pregnancy’s placenta. A small piece of the placenta is then removed and sent to the laboratory for genetic testing. Results from a CVS are usually available about 7-10 days after the procedure. Specific risks of miscarriage will be discussed at your visit.

Amniocentesis
Amniocentesis is a diagnostic test that is performed during the second or third trimesters, typically between 15 and 21 weeks of pregnancy. The main purpose of amniocentesis is usually to determine whether or not a baby has the normal number of chromosomes. Therefore, amniocentesis is diagnostic for birth defects like Down syndrome, trisomy 18, trisomy 13, and some other chromosome abnormalities. In some situations, amniocentesis can also be used to test for other genetic conditions that your baby may be at risk for based on family history or carrier screening. It is also standard to use an amniocentesis sample to screen a pregnancy for open neural tube defects (like spina bifida). Amniocentesis is done by inserting a needle through a mother’s abdomen into the amniotic fluid that a baby is floating in inside the uterus. About two tablespoons of the amniotic fluid are then removed through the needle and the fluid is sent to the laboratory for genetic testing. Results from an amniocentesis are usually available about 10-14 days after the procedure. Specific risks of miscarriage will be discussed at your visit. 

Carrier screening
Carrier screening is genetic screening that is routinely offered to all women and their partners either before pregnancy or early in pregnancy. This screening is performed in order to determine an individual’s risk of “carrying” a genetic disorder that could increase the risk to a pregnancy for that disorder. Carriers of these types of genetic disorders are typically healthy, with no signs or symptoms of the disorder, and there is usually no family history of the disorder. If you and the father of your baby are both carriers of the same genetic disorder, then any child you have together has a 1 in 4 (25%) chance of inheriting that disorder. You should be offered carrier screening for certain genetic disorders based on the ethnic backgrounds of you and the father of your baby. Carrier screening is performed on blood samples from you and/or the father of the baby and results are typically available about two weeks after blood draw.

Screening Tests

Sequential screening
The sequential screen is a screening test that combines information obtained during two stages of pregnancy to determine a pregnancy’s risk for Down syndrome, trisomy 18, and open neural tube defects (like spina bifida). The first part of the sequential screen is performed in the first trimester, between 10+ and 13+ weeks of pregnancy, and involves an ultrasound exam and a blood draw from your arm. Information about your pregnancy is then combined with the information from the ultrasound and the blood work to determine a preliminary (or part I) result, which is available about one week after your blood draw. This result will give you a specific risk for Down syndrome and trisomy 18 in the pregnancy. If these risks are higher than you are comfortable with, you will be immediately offered the option of proceeding to diagnostic testing to get a “yes or no” answer. If you do not elect diagnostic testing after the part I result, then you will return for a second blood draw in the second trimester, preferably between 16 and 18 weeks of pregnancy. Information from this blood draw will be combined with the information obtained in the first trimester and about one week later you will get your final risk assessment. With the final result you will get specific risks for Down syndrome, trisomy 18, and open neural tube defects like spina bifida. Based on these results, you can decide if you want to have diagnostic testing or not.

Other Services

Genetic consultation
Genetic consultation is available for a variety of indications. During a genetic consultation, information about you and the father of your baby’s personal and family histories will be collected and reviewed in order to determine potential risks for birth defects, genetic disorders, or certain pregnancy complications. Depending on the risks identified, you will also be provided with information regarding the screening and diagnostic testing options available to you based on these risks. Genetic consultation is available prior to pregnancy, during pregnancy, or after pregnancy for women and men. Common indications for genetic consultation include: personal or family history of birth defects, mental retardation, or known genetic disorders, recurrent miscarriage, discussion of prenatal screening and testing options related to a woman’s age-related risk or abnormal prenatal screening results (options counseling), multifetal reduction, and male factor infertility.

Periumbilical blood sampling (PUBS) or cordocentesis
PUBS is an invasive, diagnostic test that involves inserting a needle through a woman’s abdomen into a baby’s umbilical cord to obtain a sample of a baby’s blood. It is typically performed in the second or third trimesters. PUBS is used for diagnosing or treating an increasingly limited number of genetic disorder and is therefore not routinely offered to all pregnant women. The risk of miscarriage after a PUBS procedure is approximately 1 in 33 (3%).