Fetal Ultrasounds

Expectant parents are anxious to find out about their baby’s health as it grows in its mother’s womb. Fetal ultrasound allows mothers and fathers a window into their baby’s world. Currently, the amounts of women who request ultrasounds early in their pregnancies are increasing. Early ultrasounds, in the first trimester, provide comfort and reassurance to the expectant mother. Overall, ultrasounds allow the health care provider to evaluate a fetus’s gender, growth, and development. In addition, many expectant mothers realize that ultrasounds allow their doctors to predict their due date. An accurate due date allows the mother to plan her pregnancy and prepare for her baby’s arrival. However, from the health care providers’ perspectives, first and second trimester ultrasounds allow them to determine the growing fetus’s condition and progress, so an ultrasound is an invaluable procedure when assessing fetus development.  

Ultrasounds are a routine examination in every pregnancy and can be used in the first or second trimester. Trimesters are differentiated by weeks. The first trimester is usually categorized as up to 13 + 6 weeks, whereas the second trimester is typically 13 to 27 weeks. Health care providers may recommend additional ultrasounds for the pregnancy’s duration, but patients should know that they are straightforward and painless procedures. Essentially, its main task is that it “produces pictures of the inside of the body using sound waves” ("Obstetric ultrasound: What is Obstetrical Ultrasound Imaging?" 2). In the case of a pregnancy, the obstetric ultrasound takes a picture of the fetus in the woman’s uterus. An ultrasound is either performed over the lower abdominal region or transvaginal, with the transabdominal as the most common procedure for pregnancies. In both scenarios, the expectant mother may experience slight discomfort due the application of a water-based gel or by the insert of the transvaginal transducer, but she will not experience any pain. 

The ultrasound scanner uses a display screen and transducer, with the water-based gel, in order to capture images of the developing fetus. Basically, the transducer “sends out inaudible high frequency sound waves into the body and then listens for the returning echoes from the tissues in the body” ("Obstetric Ultrasound: What is Obstetrical Ultrasound Imaging?" 2). The images are real time so expectant mothers can watch the baby’s movements and see and hear its heartbeat. A baby’s development is usually a large concern for the expectant mother, so an ultrasound allows her to see her baby’s development. While some of the fetus’s features may be unclear to the untrained eye, doctors or sonographers can explain what the expectant mother is viewing as they perform the ultrasound. 

As sonographers or health care providers deliver explanations to the expectant parents, they are also taking note of any fetal anomalies. Sonographers and doctors characterize fetal anomalies as major or minor. Minor anomalies are usually not life-threatening; however, major anomalies will affect the fetus’s viability. Gliozheni et al. reveals that “Congenital abnormalities account 20 to 25% of perinatal deaths” (193). Oftentimes, abnormalities are the result of a defective gene, but only a well-trained eye can detect them. In order to differentiate between normal and abnormal, sonographers have to know what a typical embryo and fetus looks like. 

A brief, or basic, ultrasound evaluation of fetal brain functions, including movement of extremities and breathing, can help sonographers identify which procedures they should follow with each unborn baby. During the evaluation, they observe the fetal heartbeat, movement, and breathing, and determine the gestational age. As sonographers pay close attention to the fetal heartbeat, they are able to note any abnormal heart rates and congenital malformations. In addition, the brief ultrasound evaluation is useful in the clinical setting because it allows sonographers to examine the fetal central nervous system (CNS) for functional impairment.  However, the International Society of Ultrasound in Obstetrics & Gynecology explains that “a satisfying evaluation of the fetal CNS can always be obtained in the second and third trimesters” (109), so health care providers usually reserve early ultrasounds for certain occasions. Nevertheless, health care providers can evaluate the fetus’s growth and development in order to provide expectant mothers an insight as to how their pregnancies are progressing.

Sonographers pay close attention to each of the fetus’s body parts. For example, the sonographer evaluates “the fetal head and spine [and specifically note]… the lateral ventricles, the cerebellum and brain texture” (The International Society of Ultrasound in Obstetrics & Gynecology 110). Depending on the pregnancy, health care providers will recommend two-, three-, or four-dimensional ultrasounds. Two-dimensional ultrasounds (2DUS) are the most common, and they allow the sonographer to detect facial abnormalities. Gliozheni et al. explains that facial abnormalities may consist of “Lateral and median clefts. The incidence is 1:1000 [and] The defect is present in 13% of all infants with congenital anomalies” (198). Congenital implies that the defect is hereditary. In addition to clefts, a trained sonographer can detect other abnormalities such as head shape or bulging eyes which suggests Anencephaly. As Gliozheni et al. emphasizes Anencephaly “is the most common and severe anomaly of the central nervous system and the easiest to diagnose with US” (194). If a congenital abnormality is detected, health care providers will schedule either a three-dimensional ultrasound (3DUS) or a four-dimensional ultrasound (4DUS). 3DUS and 4DUS are usually more expensive, but they allow for closer looks if doctors suspect the fetus is in danger from diseases such as Tay-Sachs.  

It is worth noting that fetus abnormalities may appear as the pregnancy progresses, but an ultrasound at the end of the first trimester may provide early evidence of anomalies. In any case, health care providers do not overuse ultrasounds. "ISUOG Practice Guidelines: Performance of First-Trimester Fetal Ultrasound Scan" emphasizes that “fetal exposure times should be minimized, using the shortest scan times and lowest possible power output needed to obtain diagnostic information” (103). While early ultrasounds do not harm the fetus, most health care providers agree that ultrasounds should be used with discretion. On the other hand, with technological advancements, expectant mothers are beginning to ask for ultrasounds in their first trimester.  In the early trimester, Katorza and Achiron explains that “The development of high-frequency and high resolution (5 to 9 MHz; 6 to 12 MHz) transvaginal probes along with substantial improvement in image and signal processing have opened up new possibilities for the investigation of early pregnancy” (199). In other words, the images are detailed and clear, so the health provider is able to check for any anomalies. The transvaginal ultrasound is similar to a woman’s annual Pap smear. The small probe is inserted into her vagina and maneuvered to get the best views of the fetus. In addition to the fetus, sonographers will scan the uterus and ovaries. Typically, in the case of ectopic pregnancies and very early pregnancies, a transvaginal ultrasound is common. 

While 2DUS are able to give accurate findings regarding fetal behavior, researchers sought to improve ultrasounds in order to assess the fetus’s central nervous system. Miskovic et al. finds that 3DUS and 4DUS ultrasounds allow further assessment. The researchers’ study compared fetus behaviors, in high risk and normal pregnancies, using 4DUS. Specifically, their research was in response to lawsuits pertaining to newborn babies’ brain damage. Miskovic et al. argues that the “two main advantages of 4DUS [is] better analysis of facial expression and quality (variability and complexity) of fetal movements” (1464).  However, for the most part, 2DUS can detect anomalies so it seems that the more expensive 3DUS and 4DUS can be reserved for severe cases and not replace the 2DUS entirely. 

On the other hand, some expectant parents would like to see their baby in more detail, and 3DUS and 4DUS allow for that. Because the images are three dimensional, the expectant parents will have no trouble spotting the fetus’s facial features and overall shape. However, as Katorza and Achiron suggest the combination of first trimester and transvaginal ultrasounds allow health care providers to detect fetal anomalies early on. Furthermore, Katorza and Achiron specifically recommend first trimester ultrasounds because when fetuses exhibit severe and life-threatening anomalies, “the physical and psychological morbidity associated with a second-trimester abortion may be reduced” (200). Expectant parents would want to know if their new babies were at risk, so it is reasonable to assume that the earlier they know something is wrong, the better it is.

In sum, health care providers rely on ultrasounds to provide details that would be unknown to the naked eye. While expectant parents may view ultrasounds as a means to see their babies as soon as possible, health care providers and sonographers use them to determine any problems early on. While an ultrasound is not 100% foolproof when detecting anomalies, they offer substantial evidence that they are an essential part of a pregnant woman’s care. Pregnancy is an exciting time for most expectant mothers, so having an image of their baby may be the reason for wanting an early ultrasound, but as technology continues to progress, it may be possible that early first trimester ultrasounds will be as routine as second trimester ultrasounds. 

Works Cited

Gliozheni, Orion, Selami Sylejmani, and Kreston Kati. "Ultrasound and Diagnosis of Fetal Anomalies." Donald School Journal of Ultrasound in Obstetrics and Gynecology 5.3 (2011): 193-204. EBSCO.

International Society of Ultrasound in Obstetrics & Gynecology. "Sonographic Examination of the Fetal Central Nervous system: Guidelines for Performing the ‘basic Examination’ and the ‘fetal Neurosonogram." Ultrasound Obstet Gynecol 29 (2007): 109-16.Wiley Online Library. Wiley InterScience, 3 Jan. 2007. 

"ISUOG Practice Guidelines: Performance of First-Trimester Fetal Ultrasound Scan." Ultrasound in Obstetrics & Gynecology 41.1 (n.d.): 102-113. Science Citation Index. 

Katorza, Eldad, and Reuven Achiron. "Early Pregnancy Scanning for Fetal Anomalies—the New Standard?" Clinical Obstetrics and Gynecology 55.1 (2012): 199-216. 

Miskovic, Berivoj, Oliver Vasilj, Milan Stanojevic, Davor Ivanković, Mario Kerner, and Ana Tikvica. "The Comparison of Fetal Behavior in High Risk and Normal Pregnancies Assessed by Four-Dimensional Ultrasound." Journal of Maternal-Fetal and Neonatal Medicine 23.12 (2010): 1461-467. EBSCO. 

"Obstetric Ultrasound: What Is Obstetrical Ultrasound Imaging?" RadiologyInfo.org. n.p., 7 May 2013. http://www.radiologyinfo.org/en/pdf/obstetricus.pdf.