Ultrasound (Maternal-Newborn) - CE

ALERT

Only ultrasonographers or other health care professionals trained in ultrasonography should perform ultrasound examinations.^{undefined#ref8">8}

OVERVIEW

Ultrasound during pregnancy is a common and safe diagnostic procedure that uses sound waves to create an image of the fetus and placenta.² The image produced–the sonogram–provides visual assistance that improves safety during invasive tests.^3,5,8

The sonogram also provides clinical information about (Table 1):

• Number of fetuses
• Fetal gestational age
• Fetal aviability
• Normal versus abnormal fetal growth curves
• Fetal anatomy
• Placental location and maturity
• Fetal position
• Amniotic fluid volume
• Blood flow through the umbilical vessels
• Fetal well-being

When the sound waves of an ultrasonic beam are aimed at body tissues, they are deflected by structures of different densities in their path and returned as echoes. In obstetrics, the ultrasonic beam sent by a transducer is directed through tissues of the abdomen or vagina to provide a two- or three-dimensional image. The majority of obstetric ultrasounds are performed using two-dimensional images (Figure 1).⁸

During pregnancy, a transabdominal, transvaginal, or transperineal ultrasound examination may be performed.^3,8

• Transabdominal ultrasounds are most often used in the second and third trimesters when the pregnant uterus is easily seen in the abdominal cavity.⁸
• Transvaginal ultrasounds are most often used during the first trimester to provide imaging of the intrapelvic anatomy, to diagnose ectopic pregnancies and abnormalities, and to help determine gestational age.⁸ They can also be used later in pregnancy to provide clear imaging of placental location and to measure cervical length.⁵
• Transperineal ultrasound may be used as an alternative to transvaginal ultrasound to confirm findings from a transabdominal ultrasound or to assess any of the indicated conditions for which a transvaginal ultrasound is used.³

Transabdominal and transvaginal ultrasound may be used in conjunction during the second and third trimesters to evaluate painless vaginal bleeding after 20 weeks’ gestation and rule out placenta previa.⁶ A transabdominal ultrasound examination should be performed initially and be followed by a transvaginal ultrasound unless the transabdominal scan clearly shows that the placenta is not located in the lower uterine segment.⁶ Because of differences in imaging techniques, the transabdominal ultrasound should be performed first with the patient having a full bladder, and the transvaginal ultrasound should be performed after the patient has emptied her bladder.⁸

Ultrasonography may provide early diagnoses, allowing more options early in pregnancy. An early diagnosis of a fetal anomaly, for example, allows the family to have choices such as intrauterine surgery, other treatment therapies, termination of the pregnancy, or time to prepare for the care of a newborn with a disorder.^3,8 However, when an ultrasound examination is performed, patients should be counseled about its limitations. This should include a discussion of the sensitivity of the examination for the detection of abnormalities and potential false-positive findings.³

Obstetric ultrasound examination has three levels:

• Standard. In the second or third trimester, this basic scan includes an assessment of fetal anatomy, fetal cardiac activity, fetal presentation, the number of fetuses, the placenta, fetal biometry, and amniotic fluid volume. For gestational age dating, the ultrasound should be performed before 22 weeks’ gestation to ensure accuracy.³ The maternal cervix and adnexa may also be examined as indicated.^3,8
• Limited. Limited ultrasound in the second or third trimester is performed when the clinical situation dictates that a specific maternal or fetal assessment is needed.⁴ Limited ultrasound examinations may be performed for the number of fetuses, fetal presentation, fetal cardiac activity, fetal growth, and placental location.⁴ Limited ultrasound may also be used in any trimester to estimate amniotic fluid volume, assess embryonic or fetal viability, and evaluate the cervix.³ These examinations are not meant to evaluate or identify fetal anomalies, assess fetal age, or estimate fetal weight. The obstetric practitioner is responsible for obtaining a more comprehensive ultrasound examination when complete fetal assessment is necessary.⁴
• Specialized. The specialized (also called detailed or targeted) scan is indicated when a fetal anomaly is suspected based on abnormal laboratory values or the results of a previous standard or limited ultrasound. A perinatologist commonly consults with the patient’s primary practitioner when a specialized scan is required. The specialized scan targets the questionable finding to obtain greater detail than the basic scan reveals. Specialized scans include fetal Doppler ultrasonography, biophysical profile, and fetal echocardiography. Indications for specialized ultrasounds include suspected fetal growth restriction, suspected fetal anemia, and multifetal gestation.^3,4

The use of ultrasound for gestational dating is common in most pregnancies. Fetal age estimated by crown-rump length in the first trimester is the most accurate means for ultrasound dating of pregnancy. Starting at 14 weeks’ gestation, the biparietal diameter, abdomnal circumference, and femur length can be used to help estimate gestational age.³ The optimal time for a single ultrasound exam is 18 to 22 weeks’ gestation³ because this period can allow a survey of fetal anatomy and an accurate estimation of gestational age. If an accurate earlier scan is obtained, the gestational age should not be revised using a scan done later in pregnancy. After 22 weeks’ gestation, ultrasound dating is less reliable because of variability in the size of the fetus.^3,8

Ultrasound procedures use real-time scanning that shows movement as it happens, allowing the observer to see fetal heart motion, fetal breathing activity, and fetal body movement. Real-time scanning also allows the observer to distinguish between moving tissues of the fetus and relatively fixed maternal tissues. Advances in technology and software now can produce a three-dimensional image with greater clarity and visual depth than the two-dimensional image (Figure 2).⁸ Three-dimensional ultrasonography has not been found to provide a clinical advantage over two-dimensional ultrasound, but it may be helpful in identifying fetal facial anomalies, neural tube defects, fetal tumors, and skeletal malformations.³

PATIENT AND SUPPORT PERSON EDUCATION

• Instruct the patient and her support person regarding the purpose of the ultrasound procedure and explain what the ultrasonographer will be assessing.
• Instruct the patient and her support person regarding the safety and limitations of ultrasound.
• Instruct the patient to drink fluid before the ultrasound if a full bladder is necessary for the test she will have.
• Instruct the patient to void before the ultrasound if an empty bladder is necessary for the test she will have.
• Advise the patient regarding expected positioning and exposure, the possibility of discomfort related to a full bladder, the length of the procedure, and the viewing capabilities.
• Explain when the results will be discussed.
• Encourage questions and answer them as they arise.

ASSESSMENT AND PREPARATION

Assessment

1. Perform hand hygiene before patient contact.
2. Introduce yourself to the patient.
3. Verify the correct patient using two identifiers.
4. Verify the practitioner’s orders.
5. Assess the patient for a full or empty bladder, if indicated.

Preparation

1. Verify the integrity and functionality of all equipment and supplies to be used.
2. Ensure patient privacy.

PROCEDURE

Transabdominal Ultrasound

1. Perform hand hygiene and don gloves.
2. Verify the correct patient using two identifiers.
3. Explain the procedure to the patient and ensure that she agrees to treatment.
4. Have the patient don a patient gown if her street clothes do not allow adequate exposure.
5. Position the patient on her back with her head and knees supported. Elevate her head and turn her slightly to one side. Place a wedge or rolled blanket under one hip to help her maintain this position comfortably.

   Rationale: The patient is tilted to one side to avoid supine hypotension, which can result from the gravid uterus compressing the vena cava and aorta when the patient is supine. ⁷

6. Expose the patient’s abdomen from the ribs to the hips.

   Rationale: Adequate exposure allows the ultrasonographer to obtain the angles needed to evaluate the uterus and surrounding structures.

7. Notify the ultrasonographer or obstetric practitioner that the patient is prepared.
8. Position the display panel for the patient and support person to view if possible.
9. Remain available at the bedside to assist the ultrasonographer as needed or to notify the practitioner of any abnormalities.

   Rationale: Abnormalities should be brought to the obstetric practitioner’s attention so appropriate interventions can be performed, and further testing can be scheduled, if indicated.

10. Remove excess lubricant gel and assist the patient with cleansing the abdomen after the ultrasound procedure is completed.
11. Assist the patient to the bathroom to empty her bladder and to change her clothing, if applicable.
12. Cleanse the ultrasound transducer per the organization’s practice.
13. Discard supplies, remove gloves, and perform hand hygiene.
14. Address the questions and concerns of the patient and her support person.
15. Document the procedure in the patient’s record.

Transvaginal or Transperineal Ultrasound

1. Perform hand hygiene and don gloves.
2. Verify the correct patient using two identifiers.
3. Explain the procedure to the patient and ensure that she agrees to treatment.
4. Instruct the patient to empty her bladder, to remove all her clothing below the waist, and to don a patient gown.

   Rationale: An empty bladder helps the ultrasonographer obtain a better view of pelvic structures during a transvaginal ultrasound. ⁸

5. Position the patient on her back with her head supported and knees bent. Place a wedge or rolled blanket under one hip if the patient is past the first trimester. Place the patient’s feet in footrests as needed.

   Rationale: The patient is tilted to one side to avoid supine hypotension, which can result when the gravid uterus compresses the vena cava and aorta when the patient is supine. ⁷ A wedge is not necessary during the first trimester because the small size of the fetus poses a low risk of supine hypotension.

6. Notify the ultrasonographer or obstetric practitioner that the patient is prepared.
7. Lubricate the vaginal transducer probe with a water-soluble gel.
8. If the transvaginal approach will be used, place a protective cover over the vaginal transducer probe and apply additional water-soluble gel to the outside of the cover.
9. If the transperineal approach will be used, cover the probe with gel and a nonpowdered glove; do not apply additional gel.¹

   Rationale: The nonpowdered glove is used as a probe cover for hygiene purposes. Powdered gloves should not be used as probe covers because of the potential for reverberations of image quality. ¹

10. Position the display panel for the patient and support person to view if possible.
11. Remain available at the bedside to assist the ultrasonographer as needed or to notify the practitioner regarding any abnormalities.

    Rationale: Abnormalities should be brought to the obstetric practitioner’s attention so appropriate interventions can be performed, and further testing can be scheduled, if indicated.

12. Assist the patient to the bathroom after the ultrasound procedure so she can remove excess lubricant gel from her vaginal or perineal area and get dressed.
13. Cleanse the transvaginal transducer per the organization’s practice.
14. Discard supplies, remove gloves, and perform hand hygiene.
15. Address the questions and concerns of the patient and her support person.
16. Document the procedure in the patient’s record.

MONITORING AND CARE

1. Provide contact numbers the patient can call with questions or concerns she may have after the procedure.
2. Ensure that the patient has scheduled a follow-up appointment with her obstetric practitioner.
3. Assess, treat, and reassess pain.

EXPECTED OUTCOMES

• Adequate imaging of fetal details
• Patient tolerance of the procedure
• Absence of complications

UNEXPECTED OUTCOMES

• Poor imaging of fetal details
• Pain or poor patient tolerance of the procedure
• Complications from the procedure

DOCUMENTATION

• Ultrasound date and time
• Person performing the ultrasound
• Ultrasound findings
• Patient’s response to and tolerance of the ultrasound
• Patient and support person education
• Communication with practitioner
• Unexpected outcomes and related nursing interventions

REFERENCES

1. Albuquerque, A., Pereira, E. (2016). Current applications of transperineal ultrasound in gastroenterology. World Journal of Radiology, 8(4), 370-377. doi:10.4329/wjr.v8.i4.370
2. American College of Obstetricians and Gynecologists (ACOG) Committee on Obstetric Practice. (2017, reaffirmed 2019). Committee opinion no. 723: Guidelines for diagnostic imaging during pregnancy and lactation (Interim update). Obstetrics & Gynecology, 130(4), e210-e216. doi:10.1097/AOG.0000000000002355 (Level VII)
3. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins—Obstetrics, American Institute of Ultrasound in Medicine. (2016, reaffirmed 2018). Practice bulletin no. 175: Ultrasound in pregnancy. Obstetrics & Gynecology, 128(6), e241-e256. doi:10.1097/AOG.0000000000001815 (Level VII)
4. Association of Women’s Health, Obstetric and Neonatal Nurses (AWHONN). (2016). Ultrasound examinations performed by registered nurses in obstetric, gynecologic, and reproductive medicine settings: Clinical competencies and education guide (4th ed.). Washington, DC: AWHONN. (Level VII)
5. Cypher, B. (2019). Chapter 9: Assessing the fetus. In S.S. Murray and others (Eds.), Foundations of maternal-newborn and women’s health nursing (7th ed., pp. 178-199). St. Louis: Elsevier.
6. Montgomery, K.S. (2020). Chapter 28: Hemorrhagic disorders. In D.L. Lowdermilk and others (Eds.), Maternity & women’s health care (12th ed., pp. 598-614). St. Louis: Elsevier.
7. Spain, R.O. (2020). Chapter 19: Nursing care of the family during labor and birth. In D.L. Lowdermilk and others (Eds.), Maternity & women’s health care (12th ed., pp. 376-416). St. Louis: Elsevier.
8. Tucker, J.A. (2020). Chapter 26: Assessment of high-risk pregnancy. In D.L. Lowdermilk and others (Eds.), Maternity & women’s health care (12th ed., pp. 565-582). St. Louis: Elsevier.

ADDITIONAL READINGS

American College of Obstetricians and Gynecologists (ACOG). (2014, reaffirmed 2019). Practice bulletin no. 145: Antepartum fetal surveillance. Obstetrics & Gynecology, 124(1), 182-192. doi:10.1097/01.AOG.0000451759.90082.7b

Roberts, V. and others. (2016). Utilization and safety of contrast-enhanced ultrasound in pregnancy. AJOG: American Journal of Obstetrics & Gynecology, 214(1, Suppl.), S39. doi:10.1016/j.ajog.2015.10.073

Elsevier Skills Levels of Evidence

• Level I - Systematic review of all relevant randomized controlled trials
• Level II - At least one well-designed randomized controlled trial
• Level III - Well-designed controlled trials without randomization
• Level IV - Well-designed case-controlled or cohort studies
• Level V - Descriptive or qualitative studies
• Level VI - Single descriptive or qualitative study
• Level VII - Authority opinion or expert committee reports