Prenatal Testing

Diabetes Testing:

Glucose Tolerance Test: The glucose tolerance test, also known as the oral glucose tolerance test, measures your body's response to sugar (glucose). The glucose tolerance test can be used to screen for type 2 diabetes. More commonly, a modified version of the glucose tolerance test is used to diagnose gestational diabetes — a type of diabetes that develops during pregnancy.

Glucose Challenge Test: The glucose challenge test measures your body's response to sugar (glucose). The glucose challenge test is done during pregnancy to screen for gestational diabetes — diabetes that develops during pregnancy. The glucose challenge test is done in two steps. First you drink a sugary solution. One hour later, your blood sugar level is measured. The results of the glucose challenge test indicate whether you might have gestational diabetes. If the test results are above normal, you'll need to have further testing to determine the diagnosis.

Fetal Biophysical Profile A fetal biophysical profile is a prenatal test used to check on a baby's well-being. The test combines fetal heart rate monitoring (nonstress test) and fetal ultrasound. During a biophysical profile, a baby's heart rate, breathing, movements, muscle tone and amniotic fluid level are evaluated and given a score.Typically, a biophysical profile is recommended for women at risk of pregnancy loss. The test is usually done after week 32 of pregnancy, but can be done when your pregnancy is far enough along for delivery to be considered — usually after week 24. A low score on a biophysical profile might indicate that you and your baby need further monitoring or special care. In some cases, early or immediate delivery might be recommended.A biophysical profile is a noninvasive test that doesn't pose any physical risks to you or your baby. However, it's not always clear that a biophysical profile can help promote a baby's health. Find out what a biophysical profile involves and whether this prenatal test might benefit you or your baby.

Why it's done A biophysical profile is used to evaluate and monitor a baby's health. The goal of a biophysical profile is to prevent pregnancy loss and detect fetal hypoxia — when the baby is deprived of an adequate oxygen supply — early enough so that the baby can be delivered and not sustain permanent damage.The test is most commonly done when there's an increased risk of pregnancy loss. Your health care provider will determine the necessity and timing of a biophysical profile based on whether your baby could survive if delivered early, the severity of your condition and the risk of pregnancy loss.Your health care provider might initially recommend a modified biophysical profile — a simplified version of the test that includes a nonstress test and assesses amniotic fluid through ultrasound. Your health care provider will then use the results to determine whether you need a full biophysical profile, which also measures a baby's breathing, movements and muscle tone.Your health care provider might recommend a biophysical profile if you have:

• A multiple pregnancy with certain complicationsAn underlying medical condition, such as diabetes or heart disease

• A pregnancy that has extended two weeks past your due date (postterm pregnancy)

• A history of pregnancy loss or previous pregnancy complications

• A baby who has decreased fetal movements or possible fetal growth problems

• Preterm premature rupture of the membranes — when the fluid-filled membrane that surrounds and cushions the baby during pregnancy (amniotic sac) leaks or breaks before week 37 of pregnancy

• Too much amniotic fluid (polyhydramnios) or low amniotic fluid volume (oligohydramnios)

• Rh (rhesus) sensitization — a potentially serious condition that can occur when your blood group is Rh negative and your baby's blood group is Rh positive

• Worrisome results from other prenatal tests

• Your health care provider might also recommend a biophysical profile if you're between 40 and 42 weeks pregnant. The benefits of having the test done during this period, however, aren't clear. Your health care provider might recommend that you have a biophysical profile once a week, twice a week or, rarely, even more frequently — depending on your health condition — until you give birth.

Risks

A biophysical profile is a noninvasive test that poses no physical risks to you or your baby.

While a biophysical profile can offer reassurance about your baby's health, it can also cause anxiety. In addition, a biophysical profile might not detect an existing problem or might suggest that a problem exists when there is none.

Also, keep in mind that while a biophysical profile is often recommended for women who have an increased risk of pregnancy loss, it's not always clear that the test can promote a baby's health.

Preparing

A biophysical profile typically requires no special preparation. Rarely, the ultrasound might need to be done with a full bladder.

What you can expect

A biophysical profile can be done in your health care provider's office or in a hospital. The test might take anywhere from five minutes up to an hour to complete.

During the test

During the nonstress test, you'll lie on an exam table. You'll likely have your blood pressure taken before the test and at regular intervals during the test.

Your health care provider or a member of your health care team will then place a belt across your abdomen. The belt contains a sensor that measures the fetal heart rate. Typically, the test lasts 20 minutes. However, if your baby is asleep, you might need to wait until he or she awakens to ensure accurate results. In some cases, your health care provider might try to awaken the baby by using sound from a special device.

During the ultrasound exam, you'll also lie on an exam table. Your health care provider or an ultrasound technician will apply a small amount of gel to your abdomen. Then he or she will roll a small device called a transducer over your skin. The transducer will emit pulses of sound waves that will be translated into a pattern of light and dark areas — creating an image of your baby on a monitor.

Your health care provider or the ultrasound technician will then evaluate your baby's breathing movements, body movements, muscle tone and amniotic fluid level. The ultrasound might last five to 30 minutes or so, depending on whether your baby is awake, or there's a wait time until your baby awakens.

After the test

When the biophysical profile is complete, your health care provider will likely discuss the results with you right away

Results

Each area that's evaluated during a biophysical profile is given a score of 0 or 2 points, depending on whether specific criteria were met. A score can be given as soon as the biophysical activity is observed. For example:

• Fetal heart rate. Results of this portion of the test (nonstress test) are called reactive or nonreactive. If your baby's heartbeat accelerates twice or more within a 20-minute period, the results are considered reactive and 2 points will be given. If not enough accelerations occur within a 40-minute period, the results are considered nonreactive and 0 points will be given. Keep in mind that nonreactive results might occur because your baby was asleep during the test .

• Fetal breathing. If your baby displays at least one episode of rhythmic breathing for 30 seconds or more within 30 minutes, 2 points will be given. If your baby's breathing doesn't meet the criteria, 0 points will be given.

• Fetal movement. If your baby moves his or her body or limbs three times or more within 30 minutes, 2 points will be given. If your baby's movements don't meet the criteria, 0 points will be given.

• Fetal muscle tone. If your baby moves a limb from a bent position to an extended position and quickly back to a bent position, 2 points will be given. If your baby's muscle tone doesn't meet the criteria, 0 points will be given.

• Amniotic fluid level. The ultrasound technician will look for the largest visible pocket of amniotic fluid. To obtain a score of 2 points, the pocket must be a certain size. If your amniotic fluid level doesn't meet the criteria, 0 points will be given.

The individual scores are then added together for a total score. Typically, a score of 8 to 10 is reassuring. If you receive a score of 6, your health care provider will likely repeat the test within 24 hours. Another score of 6 or a lower score might lead your health care provider to recommend further testing or an early or immediate delivery.

In addition, if your health care provider finds that you have a low amount of amniotic fluid, you'll need further testing and might need to deliver your baby early — regardless of your overall score.

Keep in mind that certain factors can affect the results of a biophysical profile, including the use of corticosteroids to speed your baby's lung maturity and the presence of an infection. Smoking or taking certain medications also can affect the baby's heart rate.

Be sure to discuss the results of your biophysical profile with your health care provider to fully understand what they might mean for you and your baby.

Fetal Monitoring

Using A fetoscope (a type of stethoscope) to listen to the fetal heart beat is the most basic type of fetal heart rate monitoring. Another type of monitoring is with a hand held Doppler device. This is often used during prenatal visits to count the fetal heart rate. During labor, continuous electronic fetal monitoring is often used. Although the specific details of each procedure vary slightly, generally, electronic fetal monitoring follows this process:

• Gel is applied to the mother's abdomen to act as a medium for the ultrasound transducer.

• The ultrasound transducer is attached to the abdomen with straps and transmits the fetal heartbeat to a recorder. The fetal heart rate is displayed on a screen and printed onto special paper.

• During contractions, an external tocodynamometer (a monitoring device that is placed over the top of the uterus with a belt) can record the patterns of contractions.

• Sometimes, internal fetal monitoring is necessary for a more accurate reading of the fetal heart rate. Your bag of waters (amniotic fluid) must be broken and your cervix must be partially dilated to use internal monitoring. Internal fetal monitoring involves inserting an electrode through the dilated cervix and attaching the electrode to the scalp of the fetus, called a fetal scalp electrode.

Amniocentesis

An amniocentesis is a procedure used to obtain a small sample of the amniotic fluid that surrounds the fetus to diagnose chromosomal disorders and open neural tube defects (ONTDs), such as spina bifida. Testing is available for other genetic defects and disorders depending on the family history and availability of laboratory testing at the time of the procedure. An amniocentesis is generally offered to women between the 15th and 20th weeks of pregnancy who are at increased risk for chromosome abnormalities, such as women who are over age 35 years of age at delivery, or those who have had an abnormal maternal serum screening test, indicating an increased risk for a chromosomal abnormality or neural tube defect.

An amniocentesis is a procedure that involves inserting a long, thin needle through the mother's abdomen into the amniotic sac to withdraw a small sample of the amniotic fluid for examination. The amniotic fluid contains cells shed by the fetus, which contain genetic information. Although specific details of each procedure vary slightly, generally, an amniocentesis follows this process:

• The woman's abdomen is cleansed with an antiseptic.

• The doctor may or may not give a local anesthetic to numb the skin.

• Ultrasound is used to help guide a hollow needle into the amniotic sac.

• A small sample of fluid is withdrawn for laboratory analysis.

• Strenuous activities should be avoided for 24 hours following an amniocentesis.

• Women may feel some cramping during or after the amniocentesis.

Women with twins or other multiples need sampling from each amniotic sac, in order to study each baby. Depending on the position of the baby, placenta, amount of fluid, or patient's anatomy, sometimes the amniocentesis cannot be performed. The fluid is sent to a genetics laboratory so that the cells can grow and be analyzed. Alpha-fetoprotein, a protein made by the fetus that is present in the fluid, is also measured to rule out an open neural tube defect, such as spina bifida. Results are usually available in about 10 days to two weeks, depending on the laboratory.

Chorionic villus sampling (CVS) is a prenatal test that involves taking a sample of some of the placental tissue. This tissue contains the same genetic material as the fetus and can be tested for chromosomal abnormalities and some other genetic problems. Testing is available for other genetic defects and disorders depending on the family history and availability of laboratory testing at the time of the procedure. In comparison to amniocentesis (another type of prenatal test), CVS does not provide information on neural tube defects such as spina bifida. For this reason, women who undergo CVS also need a follow-up blood test between 16 to 18 weeks of their pregnancy, to screen for neural tube defects.

CVS may be offered to women who are at increased risk for chromosomal abnormalities or have a family history of a genetic defect that is testable from the placental tissue. CVS is usually performed between the 10th and 12th weeks of pregnancy. Although exact methods can vary, the procedure involves inserting a small tube called a catheter through a woman's vagina and into her cervix and usually follows this process:

• Ultrasound is used to guide the catheter into place near the placenta.

• Tissue is removed using a syringe on the other end of the catheter.

• Another method is transabdominal CVS, which involves inserting a needle through the woman's abdomen and into her uterus to sample the placental cells.

• Women may feel some cramping during and after the CVS procedure.

• The tissue samples are sent to a genetic laboratory to grow and be analyzed. Results are usually available in about 10 days to two weeks, depending on the laboratory.

Women with twins or other multiples usually need sampling from each placenta. However, because of the complexity of the procedure, and positioning of the placentas, CVS is not always feasible or successful with multiples.

Some women may not be candidates for CVS or may not obtain results that are 100 percent accurate, and may therefore require a follow-up amniocentesis. In some cases there is an active vaginal infection, such as herpes or gonorrhea, which will prohibit the procedure. Other times the doctor obtains a sample that does not have enough tissue to grow in the laboratory, such that results are incomplete or inconclusive.

Sterile Vaginal Exams: This is to check whether your cervix is thinning and opening (effacing and dilating)

Urine Testing is done by urinating into a specimen container

• Sugar It's normal to occasionally have a small amount of sugar in your urine during pregnancy, but if you have elevated levels at a couple of prenatal visits in a row or a very high level at one visit, it could mean you have gestational diabetes. Your practitioner may have you take a glucose challenge test to find out whether that's the case. (Even if your urine test results are normal, you'll have a glucose challenge test between 24 and 28 weeks to check for this relatively common condition.)

• Protein Excess protein in your urine can be a sign of a urinary tract infection (UTI), kidney damage, or certain other disorders. Later in your pregnancy, it can also be a sign of preeclampsia if it's accompanied by high blood pressure. If you have protein in your urine but your blood pressure is normal, your provider may send a clean-catch midstream sample to the lab in a sterile container to test for a UTI.

• Ketones Ketones are produced when the body starts breaking down stored or ingested fat for energy. This can happen when you're not getting enough carbohydrates (your body's usual source of energy). If you're suffering from severe nausea and vomiting or you've lost weight during pregnancy, your practitioner may check your urine for ketones. If your ketone reading is high and you can't keep any food or liquid down, you may need intravenous fluids and medication. If ketones are found in combination with sugar, it could be a sign of diabetes.

• Blood cells or bacteria On your first prenatal visit, your urine sample will most likely be screened for bacteria that indicate a UTI through a laboratory urinalysis and a culture and sensitivity test. (The culture shows whether you have a UTI, and the sensitivity test shows which antibiotics can effectively treat the infection.) If this initial test is negative, your risk of developing a UTI later in pregnancy is small, unless you have a history of chronic or recurrent UTIs.

You may continue to have dipstick tests during your pregnancy or you may only have one if you show symptoms. The dipstick test checks for a certain enzyme (produced by white blood cells) and nitrites (produced by certain bacteria), both of which signal a UTI. If either of these shows up on a dipstick test, a sterile urine sample will be sent to the lab for a culture and sensitivity test. You usually have to wait about 48 hours for the results of a urine culture and sensitivity test. However, your practitioner may start you on some kind of antibiotics before the testing is complete, particularly if you have symptoms of a urinary tract infection. You'll be tested again after treatment of a UTI and at regular intervals during your pregnancy if your provider feels you're at risk for recurrent UTIs – for example, if you have a history of kidney infection or frequent UTIs. While UTIs usually cause painful symptoms when you're not pregnant, it's possible to have a UTI with no symptoms during pregnancy. If left untreated, even a painless, symptomless UTI can progress to a full-blown kidney infection, which almost always requires hospitalization.

Blood tests that are offered

Blood tests are a routine part of your antenatal care in pregnancy. When you go for your booking appointment, either with your midwife or your GP, you’re likely to be offered some or all of the following blood tests. This is to check, among other things, your blood group, whether you have any infections or diseases and whether your baby has any fetal abnormalities. All blood tests you are offered are optional. Your GP or midwife will explain to you what they are, so you can decide whether or not you want to have them. It’s natural to be worried about them but blood tests give you and your midwife or doctor important information about your health. They can also highlight any potential problems in your pregnancy.

Blood Tests

• Blood group Your blood group is important to know, just in case you need a transfusion during pregnancy or birth. Blood group O is the most common. Groups A, B, and AB are less so.

• Rhesus (Rh) factor Your doctor and midwife need to know your rhesus status. If you're rhesus positive (RhD positive), you have a particular protein on the surface of your red blood cells. If you're rhesus negative (RhD negative), you don't. If you're rhesus negative and your baby's dad is positive, there's a good chance your baby will be rhesus positive, too. In this case, your body may produce antibodies that start to attack your baby's red blood cells. Injections of a substance called immunoglobulin, given at 28 weeks, should prevent this happening. Read more about what it means to be rhesus negative.

• Two maternal serum (blood) tests. The blood tests measure two substances found in the blood of all pregnant women:

• Pregnancy-associated plasma protein screening (PAPP-A)--a protein produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk for chromosome abnormality.

• Human chorionic gonadotropin (hCG)--a hormone produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk for chromosome abnormality.

• Hemoglobin levels A blood test can tell you if your hemoglobin levels are low, which is a sign of iron-deficiency anemia. Your body needs iron to produce haemoglobin to carry oxygen around the body in your red blood cells. If you're ananemicue to iron deficiency, your GP or midwife will talk to you about the best foods to eat to boost your iron stores. She's also likely to prescribe iron tablets, as this is the best way to treat anemia in pregnancy. Your hemoglobin levels will be checked again at 28 weeks. If you suffer a lot from tiredness or are carrying twins or more, your midwife will arrange for a blood test earlier to see if you're anemic.

• Syphilis Thankfully, this sexually transmitted disease is rare nowadays. However, if you have it and it isn't treated during pregnancy, it could cause abnormalities in your baby. Syphilis can also cause a baby to be stillborn. The blood test for syphilis can sometimes produce a false positive result. This is because it's hard to tell the bacteria that cause syphilis from other similar bacteria that commonly cause non-sexually transmitted diseases. If you're diagnosed with syphilis, you'll be treated with penicillin. This may be enough to protect your baby from the disease, although some babies need antibiotics after the birth.

• HIV/AIDS All moms-to-be are offered a blood test to detect HIV and AIDS. You can turn it down if you want to. However, knowing that you have the infection means that steps can be taken to reduce the chance of the virus being transmitted to your baby. Find out more about HIV and AIDS in pregnancy.

• SICKLE-CELL You should be offered a test for sickle-cell disease or thalassaemia at your booking appointment if there is a chance that you have these disorders. They can make you anemic and can be passed on to your baby. Group B Streptococcus (GBS) are bacteria found in the lower genital tract of about 25 percent of all women. GBS infection usually causes no problems in women before pregnancy, but can cause serious illness in the mother during pregnancy. GBS may cause chorioamnionitis (a severe infection of the placental tissues) and postpartum infection. Urinary tract infections caused by GBS can lead to preterm labor and birth, or pyelonephritis and sepsis.

• GBS is the most common cause of life-threatening infections in newborns, including pneumonia and meningitis. Newborn babies contract the infection during pregnancy or from the mother's genital tract during labor and delivery.

The Centers for Disease Control and Prevention recommends screening of all pregnant women for vaginal and rectal group B strep colonization between 35 to 37 weeks' gestation. Treatment of mothers with certain risk factors or positive cultures is important to reduce the risk of transmission of GBS to the baby. Babies whose mothers receive antibiotic treatment for a positive GBS test are 20 times less likely to develop the disease than those without treatment. What do genetic screening methods include?

• Genetic screening methods may include the following:

• Ultrasound scan

• Alpha-fetoprotein test (AFP) or multiple marker test

• Chorionic villus sampling (CVS)

• Amniocentesis

• Percutaneous umbilical blood sampling (withdrawing a small sample of the fetal blood from the umbilical cord)

• Thalassemia

• Sickle cell anemia

• Polycystic kidney disease

• Tay-Sachs disease Ultrasound An ultrasound scan is a diagnostic technique which uses high-frequency soundwaves to create an image of the internal organs. A screening ultrasound is sometimes done during the course of a pregnancy to check normal fetal growth and verify the due date. Ultrasound is a technique that is constantly being improved and refined. As with any test, results may not be completely accurate. However, ultrasound can give valuable information for parents and healthcare providers to help manage and care for the pregnancy and fetus. In addition, ultrasound gives parents a unique opportunity to see their baby before birth, helping them to bond and establish an early relationship.Ultrasounds may be done at various times throughout pregnancy for different reasons:

• To establish the due date -- this is the most accurate way of determining the due date To determine the number of fetuses and identify placental structures To diagnose an ectopic pregnancy or miscarriage To examine the uterus and other pelvic anatomy In some cases to detect fetal abnormalities Mid-trimester (sometimes called the 18 to 20 week scan)

• To confirm the due date -- a due date set in the first trimester is rarely changed

• To determine the number of fetuses and examine the placental structures

• To assist in prenatal tests, such as an amniocentesis To examine the fetal anatomy for presence of abnormalities

• To check the amount of amniotic fluid To examine blood flow patterns

• To observe fetal behavior and activity To examine the placenta To measure the length of the cervix

• To monitor fetal growth

• Third trimester To monitor fetal growth

• To check the amount of amniotic fluid As part of the biophysical profile

• To determine the position of a fetus To assess the placenta How is an ultrasound scan done? Although the specific details of each procedure vary slightly, generally, ultrasounds follow this process. Abdominal Ultrasound In an abdominal ultrasound, gel is applied to the abdomen and the ultrasound transducer glides over the gel on the abdomen to create the image. Transvaginal ultrasoundIn a transvaginal ultrasound, a smaller ultrasound transducer is inserted into the vagina and rests against the back of the vagina to create an image. A transvaginal ultrasound produces a sharper image and is often used in early pregnancy.

• There are several types of ultrasound imaging techniques.

• The most common is 2 dimensional, or 2D. This gives a flat picture of one aspect of the image.

• If more information is needed, a 3D ultrasound exam can be done. This technique, which provides a three-dimensional picture, requires a special machine and special training. But the 3D image allows the healthcare provider to see width, height, and depth of images, which can be helpful in diagnosis.

• The 3D images can also be captured and saved for later review.

• The latest technology is 4D ultrasound, which allows the healthcare provider to visualize the unborn baby moving in real-time. With 4D imaging, a 3-dimensional image is continuously updated, providing a "live action" view. These images often have a golden color, which helps show shadows and highlights.

• Ultrasound images may be captured in still photographs or on video to document findings. What are the risks and benefits of ultrasound?

• Fetal ultrasound has no known risks other than mild discomfort due to pressure from the transducer on the abdomen or in the vagina. No radiation is used during the procedure. Transvaginal ultrasound requires covering the ultrasound transducer in a plastic or latex sheath, which may cause a reaction in women with a latex allergy. Fetal ultrasound is sometimes offered in nonmedical settings to provide keepsake images or videos for parents. While the ultrasound procedure itself is considered safe, it is possible that untrained personnel may give parents false assurances about their baby's well-being, or perhaps an abnormality may be missed. Having ultrasound done by trained medical personnel who can correctly interpret findings is recommended. Talk with your doctor or midwife if you have questions.

Resources: Mayo Clinic Guide To A Healthy Pregnancy. Labor and delivery, postpartum care Harms, Roger W., M.D., et al, Part 4. Planning Your Pregnancy and Birth Third Ed. The American College of Obstetricians and Gynecologists, Ch. 8. Lamaze International, http://www.lamaze.org/ American Pregnancy Association Inducing Labor https://www.babycenter.com/0_inducing-labor_173.bc Baby center Epidural pain relief for labor https://www.babycenter.com/0_epidural-pain-relief-for-labor_1489911.bc All about Episiotomy, c-sections: Giving birth by cesarean section, what is a membrane sweep? Amniocentesis, Blood tests in first trimester, blood tests in second trimester WebMF Labor and Delivery Medical Procedures

Johns Hopkins Medicine http://www.mayoclinic.org/tests-procedures/biophysical-profile/basics/results/prc-20020015