How Sonography Has Helped Detect Birth Defects

Birth defects and other disorders occur in more than 150 thousand births each year. Most causes of birth defects remain unknown, but with new technology and advanced use of ultrasounds during prenatal visits, many physical birth defects are diagnosed prior to birth. The use of newer high resolution sonograms  combined with genetic testing can detect some conditions that involve a mental disability such as Down’s syndrome prior to birth. The risk factor for this and other conditions may be evaluated using a combination of genetic testing, blood tests, and sonograms. As technology evolves, sonograms are able to detect a wide range of physical defects. The terms, sonogram, or ultrasound is often used interchangeably to describe the use of sound waves to create a sonogram (picture) of the developing fetus.

Besides Down’s syndrome, some of the more common birth defects diagnosed with sonograms include spina bifida, missing limbs, urinary defects, and heart abnormalities. Cleft palate, brain cysts, and kidney defects are other conditions that can be evaluated during a sonogram. Specific birth defects may be diagnosed or evaluated at various stages of pregnancy. Routine ultrasounds in the first trimester also verify normal development of the fetus. This serves as a baseline should other ultrasounds be necessary later.

There are seven types of sonogram or ultrasounds used to detect birth defects during pregnancy. A transvaginal scan or ultrasound is done during early pregnancy to check for fetal heartbeat and growth. A transvaginal scan can also detect ectopic pregnancies (Fetal placement outside of the womb). Doppler ultrasound is useful in monitoring blood flow and a fetal heartbeat. Doppler ultrasounds are noninvasive and often done routinely throughout pregnancy. Advanced ultrasounds may be ordered to follow up on the early routine screenings if a defect or concern is noted during early prenatal visits. Advanced ultrasound exams are often referred to as Level II ultrasounds. Standard ultrasounds (Level I ultrasounds) are those most expectant mothers routinely experience during prenatal visits. Newer 3-D and Dynamic (4-D) ultrasounds provide a realistic picture of the developing fetus but since there is debate over the ability of the advanced images to provide new information not seen in standard ultrasounds, some insurance companies will not cover the cost of 3-D or 4-D imaging. Insurance companies often view the use of these advanced ultrasounds as investigative sonograms  rather than a medical necessity. Fetal echocardiography uses sonograms to study development and health of the baby’s heart. Several heart defects are correctible prior to birth.

First trimester sonograms are usually transvaginal or Doppler ultrasounds preformed during routine prenatal visits. With the advancement of technology, first trimester sonograms are proving to be useful in evaluating greater number of defects and conditions. The baseline ultrasound done during the first trimester can detect proper gestational age, placenta condition, and placement of the placenta, multiple fetuses, as well as any ovarian masses or fibroids that may interfere with a normal pregnancy. As previously noted, when combined with blood tests, Down’s syndrome is also possible to detect during the first trimester by measuring the amount of fluid present at the base of the baby’s neck (nuchal translucency measurement) along with evaluation of the nasal bone and blood tests. During the first trimester, a number of physical defects including missing limbs, and heart abnormalities can be evaluated along with normal or abnormal development of the uterus and ovaries. Anencephaly and exencephaly are major neural defects that involve the development of the brain that are detected during the first trimester.

The greatest amount of information available to evaluate fetal growth and development is available from sonograms done during the second trimester. While most second trimester sonograms confirm growth and development, it is during the second trimester that major neural tube defects such as spina bifida are detected. It is also possible for a closer head to toe physical exam of the baby to be done at this time. Second trimester sonograms may be used to follow up any earlier concerns detected on an ultrasound done during the first trimester. Some congenital heart defects are corrected in the womb during the second or third trimester.

The third trimester is one of rapid weight gain. 3-D or dynamic ultrasounds done during the third trimester can also provide a “first picture” of the baby that parents often appreciate. While most birth defects are detected during sonograms done in the first and second trimester, a third trimester sonogram is useful in evaluating the growth and development of the fetus. Doppler studies to evaluate blood flow, placenta health and fetal movement all provide evaluation and monitoring of any concerns detected earlier. Third trimester sonograms are also sometimes used to determine the viability of an early delivery due to birth defects or complication.

The addition of ultrasounds to evaluate and monitor the growth and development of the fetus throughout all stages of pregnancy has provided opportunity for parents know about medical issues and conditions before their baby arrives. Parents with known genetic risks or a family history of defects a sonogram can provide peace of mind. For some this may raise issues as to the expected quality of life and the decision to continue a pregnancy if a fetus has life-threatening medical issues not likely to be treatable after birth. For other parents simply knowing the challenges they may expect due to a baby’s birth defects gives time to prepare themselves and their home to provide extra support needed. Sonogram provides information needed for parents to explore all options for planning for the birth of their baby.