Screening Tests and the Diagnostic Process

During pregnancy, all women will have certain blood and urine screening tests. Blood tests will be used to confirm the pregnancy, find out the mother’s blood type and Rh factor, and determine iron, hemoglobin and glucose levels. These blood tests will be repeated to see if the mother is developing anemia or diabetes during the pregnancy.

Blood tests may also be used to see if the mother has antibodies to certain diseases, like rubella, or if she has been exposed to sexually transmitted diseases, like HIV, or has infections, like toxoplasmosis. All of these may cause birth defects or other problems for the infant. A certain type of blood test, called an alpha-fetoprotein (AFP) test, screens for conditions such as spina-bifida and Down syndrome.

More common than blood tests, urine tests are used to screen for diabetes, urinary tract infections, and pregnancy-induced hypertension (preeclampsia), all of which can affect the baby, and cause great discomfort to the mother.

Ultrasound (or sonogram) exams are used to view images of the developing fetus. They are used more often in later pregnancy to look at or measure parts of the fetus, such as the head, arms, legs, and heart. Parents may be more familiar with the tests being used to determine the gestational age or sex of the fetus, but there are other types of ultrasound exams that use different equipment, placed in different locations, that can be helpful in finding structural birth defects, high or low levels of amniotic fluid, and abnormalities in the uterus or placenta. Sometimes, when certain medical problems are suspected, an ultrasound exam will be used to help guide a needle to gather umbilical cord blood for a cordiocentesis, or a percutaneous umbilical cord blood sampling (PUBS) test, that can detect infections, blood levels, and malformations.

Parents may be referred to a genetic counselor before or during pregnancy to discuss potential risks of passing on genetic conditions and ways of treating known genetic conditions. Many genetic conditions can be found through testing the growing fetus during pregnancy (see Newborn Disorders). Genetic testing can be done using a few different screening or diagnostic tests.

• Chorionic villus sampling (CVS) tests cells from the placenta early in pregnancy to diagnose genetic conditions or chromosomal abnormalities such as cystic fibrosis and Down syndrome.
• Amniocentesis is done later in pregnancy to diagnose some of the same genetic conditions as CVS testing, as well some birth defects that are found in blood test screening. Late in pregnancy, the amniocentesis test can determine if the lungs of the fetus are mature enough before delivery and help doctors determine the best treatment options.

On or after the 28th week of pregnancy, and during labor, the non-stress test may be used to check fetal movement, heart rate, and contractions. The monitoring is done by attaching belts to the mother’s abdomen to determine if the fetus is reacting well to contractions by watching increases and decreases in movement and heart rate. This test is non-invasive and does not stress the fetus. When an ultrasound exam is combined with a non-stress test, a biophysical profile can be determined, including heart rate, breathing rate, movements, muscle tone, and amniotic fluid levels. If the non-stress test shows a problem, it may be followed by a stress test, using a medication called Pitocin to make the uterus contract, so that the doctors can find out if the fetus is having distress and determine the best plan of action.

In the last few weeks of pregnancy, women should be tested for Group B streptococcus (also referred to as beta strep). This is important because it does not always cause symptoms, and you can carry the bacteria. Women who test positive (about 1 in 4) will be treated with antibiotics so that it is not transmitted to the infant during delivery. Infants that are exposed to the Group B streptococcus bacteria can develop an infection that can enter the blood, lungs, and spinal fluid, potentially causing severe complications that can affect breathing, kidney function, and blood pressure. Infected infants are also treated with antibiotics.

Infants are screened or checked for genetic and chronic conditions using a blood test done two or three times shortly after birth. These tests are sometimes called “newborn screening” or “blood-spot screening” because the tests use a card with five circles of blood spots. These tests look for some common and some rare conditions, such as cystic fibrosis, phenylketonuria (PKU), sickle cell disease, or congenital hypothyroidism (see Newborn Disorders). It is important to catch these conditions early since they often require life-long treatments and some require special diets. This routine testing does not offer the most accurate or final tests, and if a child tests positive, the doctor will usually order more tests before the primary care doctor can make a diagnosis. Sometimes infants may need to visit a specialist for further examinations or reading of these tests.

Newborn infants also have their hearing screened or tested. Since infants are not able to talk or indicate that they can hear, these tests check for nerve responses. The tests, using electronic equipment, can be done while the infant sleeps. For more details, see Universal Newborn Hearing Screening (My Baby's Hearing). Infants who do not “pass” the first screening tests will have more accurate follow-up tests that can better determine if there is any hearing impairment. If there is some type of hearing impairment, specialists will be involved in determining what type, if there is a particular cause, and how it will be treated or managed (see Hearing Screening).

In the context of child development, “surveillance” refers to the continuous process of asking about a child's growth and watching the child reach milestones (see Developmental Screening). The primary care doctor in the medical home will often observe your child and ask about feeding, playing, and talking as part of this process. While these questions may seem like everyday conversations, they can offer clues about appropriate development or possible developmental delays.

This type of screening is a more formal process of monitoring developmental milestones. The medical home team will use tested, standardized screening tools at specific visits to see if the child has reached or missed key milestones. Parents will help complete forms for the screening tool which are reviewed and scored by the primary care doctor to decide if the child is developing on schedule or needs a closer look. Screening does not diagnose a developmental delay, but it gives clues if there may be something that needs further testing, assessment, or evaluation.

If a primary care doctor notices problems with the developmental screening, she will refer the child for further assessment that will be specific to the child’s possible problems. A common first step is a referral to a local Early Intervention Part C Program (EI). The EI provider will probably do more testing, assessments, and find interventions to help the child maintain and gain skills. Sometimes, EI providers are also Early Head Start providers, who serve children up to age three. It’s common for children to already be receiving services from Early Intervention or Early Head Start providers before a diagnosis has been determined. The child may also be referred to a developmental pediatrician, who specializes in diagnosing and treating developmental delays. For school-age children, if additional information is needed about school skills, a school psychologist may be involved in the assessment and diagnosis.

When a problem is found or a diagnosis is made, the medical home will play an important role in supporting the treatment plan and coordinating care among different providers. The medical home will provide treatment or help families find other providers if the developmental delays are mild and there is no diagnosis.

An example of Developmental Surveillance, Screening, and Diagnosis:

Ramon’s mother brings Ramon for his 15 month well child visit. At that visit, Dr. Black asks how many words Ramon can say. Dr. Black observes that Ramon responds to his name and babbles but does not speak any recognizable words. This is developmental surveillance. Dr. Black is a little worried that Ramon has a language delay, because most typically developing children have started saying words by this age. The physician encourages his mother to read and talk to him a lot over the next 3 months. He also sends Ramon for a hearing test (see Hearing Tests (My Baby's Hearing)), a diagnostic test meant to rule out hearing loss as the reason Ramon doesn’t speak recognizable words. The results of the test indicate that Ramon hears just fine.

At Ramon’s 18 month well child visit, Dr. Black follows up on his initial concerns and asks Ramon’s parents to fill out forms for two screening tests. One of these is a developmental screening test, such as the Parent's Evaluation of Developmental Status (PEDS), (see Parent's Evaluation of Developmental Status (PEDS) site) and the other is an autism-specific screening test, such as the M-CHAT (Modified Checklist for Autism in Toddlers) ( 117 KB). After reviewing the information provided by the family, Dr. Black is concerned that Ramon may have a language delay related to an autism spectrum disorder. He then refers Ramon to a psychologist for a diagnostic test for autism spectrum disorders, such as the Autism Diagnostic Observation Schedule (ADOS) test. Ramon’s score on the test reveals that he does not have an autism spectrum disorder. The cognitive testing shows that Ramon does not have intellectual disability or a low IQ. He is diagnosed with an expressive language delay.

Ramon then works with Early Intervention to receive speech and language therapy, and his language skills gradually improve over the next two years. At each subsequent visit, Ramon’s doctor continues to do surveillance by asking questions about Ramon’s development and provides encouragement to the family by noticing the improvements Ramon is making.

Developmental screening is part of routine well child care and does not cost families extra. When children need additional assessment or treatment, insurance may cover those costs. For families without insurance, publicly funded services or insurance coverage may be available.

In addition to the medical home, schools often perform certain screening tests, including hearing, vision, and scoliosis (spine) screening. Depending upon the state and the specific screening test, parents may need to provide a signed consent form for their child to have a screening test. School nurses or volunteers may help provide the screening tests and refer concerns about the test results to the child’s medical home. These tests do not diagnose a medical condition, but they can help identify children who may need a closer look or further evaluation by specialists using more sensitive equipment.

Well child checkups are appointments for children of all ages during which primary care doctors will determine if children are on track for growth and development. These visits are scheduled for certain ages, with more frequent visits for infants, and yearly visits for older children and teenagers (see Bright Futures/AAP Periodicity Schedule ( 119 KB)). Parents need to take their children to these well child checkups even if their child has been to a doctor or other clinics for sicknesses.

During each visit, the child's height and weight will be measured and recorded on growth charts. Immunizations will be given at the right ages, according to a standardized schedule. Hearing, vision, lead, developmental, autism, and other screening tests will be done at appropriate ages. The primary care doctor will also ask about age-appropriate development, such as learning to talk for young children or sexual maturation for teenagers. These visits also provide time for parents to ask about their child’s health and behavior, and for the medical home to teach parents about child safety issues, such as the proper use of car seats and bike helmets, or to discuss issues surrounding the use of harmful drugs.

Children that have a chronic medical condition, such as diabetes, cerebral palsy, asthma, autism, or bipolar disorder, will need to visit their medical home more frequently than the usual well child visits. These chronic care visits are regularly-scheduled visits in addition to acute care visits for illnesses or unexpected problems. Children will still need to have well child visits to screen for other problems and get vaccinations at the right ages.

The medical home will usually schedule additional time for chronic care visits since the primary care doctor will spend more time with the child for tests, physical evaluations, medication reviews, and teaching.