Nuchal Translucency Evaluation at 11 to 14 Weeks Gestational Age

Variant: 1 Routine nuchal translucency measurement at 11 to 14 weeks of gestation for single or twin gestations. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
US pregnant uterus transabdominal	Usually Appropriate	O
US pregnant uterus transvaginal	May Be Appropriate	O
US duplex Doppler pregnant uterus	Usually Not Appropriate	O
US echocardiography fetal	Usually Not Appropriate	O

Variant: 2 Increased nuchal translucency measurement at 11 to 14 weeks of gestation for single gestation.

Procedure	Appropriateness Category	Relative Radiation Level
US echocardiography fetal	Usually Appropriate	O
US pregnant uterus transabdominal	Usually Appropriate	O
US duplex Doppler pregnant uterus	May Be Appropriate	O
US pregnant uterus transvaginal	May Be Appropriate	O

Variant: 3 Increased nuchal translucency in dichorionic twins at 11 to 14 weeks of gestation.

Procedure	Appropriateness Category	Relative Radiation Level
US echocardiography fetal	Usually Appropriate	O
US pregnant uterus transabdominal	Usually Appropriate	O
US duplex Doppler pregnant uterus	May Be Appropriate	O
US pregnant uterus transvaginal	May Be Appropriate	O

Variant: 4 Increased nuchal translucency in monochorionic twins at 11 to 14 weeks of gestation.

Procedure	Appropriateness Category	Relative Radiation Level
US echocardiography fetal	Usually Appropriate	O
US pregnant uterus transabdominal	Usually Appropriate	O
US duplex Doppler pregnant uterus	May Be Appropriate	O
US pregnant uterus transvaginal	May Be Appropriate	O

Panel Members

Lynn Simpson, MD^a; Katherine E. Maturen, MD, MS^b; Vickie A. Feldstein, MD^c; Edward R. Oliver, MD, PhD^d; Liina Poder, MD^e; Loretta M. Strachowski, MD^f; Betsy L. Sussman, MD^g; Therese M. Weber, MD^h; Tom Winter, MD, MAⁱ; Carolyn M. Zelop, MD^j; Phyllis Glanc, MD^k.

Summary of Literature Review

Introduction/Background

Special Imaging Considerations

Initial Imaging Definition

Initial imaging is defined as imaging at the beginning of the care episode for the medical condition defined by the variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when:

There are procedures that are equivalent alternatives (i.e., only one procedure will be ordered to provide the clinical information to effectively manage the patient’s care)

There are complementary procedures (i.e., more than one procedure is ordered as a set or simultaneously wherein each procedure provides unique clinical information to effectively manage the patient’s care).

Discussion of Procedures by Variant

Variant 1: Routine nuchal translucency measurement at 11 to 14 weeks of gestation for single or twin gestations. Initial imaging.

Variant 1: Routine nuchal translucency measurement at 11 to 14 weeks of gestation for single or twin gestations. Initial imaging.
A. US duplex Doppler pregnant uterus

Variant 1: Routine nuchal translucency measurement at 11 to 14 weeks of gestation for single or twin gestations. Initial imaging.
B. US echocardiography fetal

Variant 1: Routine nuchal translucency measurement at 11 to 14 weeks of gestation for single or twin gestations. Initial imaging.
C. US pregnant uterus transabdominal

Variant 1: Routine nuchal translucency measurement at 11 to 14 weeks of gestation for single or twin gestations. Initial imaging.
D. US pregnant uterus transvaginal

Variant 2: Increased nuchal translucency measurement at 11 to 14 weeks of gestation for single gestation.

Variant 2: Increased nuchal translucency measurement at 11 to 14 weeks of gestation for single gestation.
A. US duplex Doppler pregnant uterus

Variant 2: Increased nuchal translucency measurement at 11 to 14 weeks of gestation for single gestation.
B. US echocardiography fetal

Variant 2: Increased nuchal translucency measurement at 11 to 14 weeks of gestation for single gestation.
C. US pregnant uterus transabdominal

Variant 2: Increased nuchal translucency measurement at 11 to 14 weeks of gestation for single gestation.
D. US pregnant uterus transvaginal

Variant 3: Increased nuchal translucency in dichorionic twins at 11 to 14 weeks of gestation.

Variant 3: Increased nuchal translucency in dichorionic twins at 11 to 14 weeks of gestation.
A. US duplex Doppler pregnant uterus

Variant 3: Increased nuchal translucency in dichorionic twins at 11 to 14 weeks of gestation.
B. US echocardiography fetal

Variant 3: Increased nuchal translucency in dichorionic twins at 11 to 14 weeks of gestation.
C. US pregnant uterus transabdominal

Variant 3: Increased nuchal translucency in dichorionic twins at 11 to 14 weeks of gestation.
D. US pregnant uterus transvaginal

Variant 4: Increased nuchal translucency in monochorionic twins at 11 to 14 weeks of gestation.

Variant 4: Increased nuchal translucency in monochorionic twins at 11 to 14 weeks of gestation.
A. US duplex Doppler pregnant uterus

Variant 4: Increased nuchal translucency in monochorionic twins at 11 to 14 weeks of gestation.
B. US echocardiography fetal

Variant 4: Increased nuchal translucency in monochorionic twins at 11 to 14 weeks of gestation.
C. US pregnant uterus transabdominal

Variant 4: Increased nuchal translucency in monochorionic twins at 11 to 14 weeks of gestation.
D. US pregnant uterus transvaginal

Summary of Recommendations

Safety Considerations in Pregnant Patients

Imaging of the pregnant patient can be challenging, particularly with respect to minimizing radiation exposure and risk. For further information and guidance, see the following ACR documents:

· ACR–SPR Practice Parameter for the Safe and Optimal Performance of Fetal Magnetic Resonance Imaging (MRI)

· ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Patients with Ionizing Radiation

· ACR-ACOG-AIUM-SMFM-SRU Practice Parameter for the Performance of Standard Diagnostic Obstetrical Ultrasound

· ACR Manual on Contrast Media

· ACR Manual on MR Safety

Supporting Documents

The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

For additional information on the Appropriateness Criteria methodology and other supporting documents, please go to the ACR website at https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Appropriateness-Criteria.

Appropriateness Category Names and Definitions

Appropriateness Category Name	Appropriateness Rating	Appropriateness Category Definition
Usually Appropriate	7, 8, or 9	The imaging procedure or treatment is indicated in the specified clinical scenarios at a favorable risk-benefit ratio for patients.
May Be Appropriate	4, 5, or 6	The imaging procedure or treatment may be indicated in the specified clinical scenarios as an alternative to imaging procedures or treatments with a more favorable risk-benefit ratio, or the risk-benefit ratio for patients is equivocal.
May Be Appropriate (Disagreement)	5	The individual ratings are too dispersed from the panel median. The different label provides transparency regarding the panel’s recommendation. “May be appropriate” is the rating category and a rating of 5 is assigned.
Usually Not Appropriate	1, 2, or 3	The imaging procedure or treatment is unlikely to be indicated in the specified clinical scenarios, or the risk-benefit ratio for patients is likely to be unfavorable.

Relative Radiation Level Information

Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, because of both organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for pediatric examinations are lower as compared with those specified for adults (see Table below). Additional information regarding radiation dose assessment for imaging examinations can be found in the ACR Appropriateness Criteria^® Radiation Dose Assessment Introduction document.

Relative Radiation Level Designations
Relative Radiation Level*	Adult Effective Dose Estimate Range	Pediatric Effective Dose Estimate Range
O	0 mSv	0 mSv
☢	<0.1 mSv	<0.03 mSv
☢☢	0.1-1 mSv	0.03-0.3 mSv
☢☢☢	1-10 mSv	0.3-3 mSv
☢☢☢☢	10-30 mSv	3-10 mSv
☢☢☢☢☢	30-100 mSv	10-30 mSv
*RRL assignments for some of the examinations cannot be made, because the actual patient doses in these procedures vary as a function of a number of factors (e.g., region of the body exposed to ionizing radiation, the imaging guidance that is used). The RRLs for these examinations are designated as “Varies.”

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Disclaimer

The ACR Committee on Appropriateness Criteria and its expert panels have developed criteria for determining appropriate imaging examinations for diagnosis and treatment of specified medical condition(s). These criteria are intended to guide radiologists, radiation oncologists and referring physicians in making decisions regarding radiologic imaging and treatment. Generally, the complexity and severity of a patient’s clinical condition should dictate the selection of appropriate imaging procedures or treatments. Only those examinations generally used for evaluation of the patient’s condition are ranked. Other imaging studies necessary to evaluate other co-existent diseases or other medical consequences of this condition are not considered in this document. The availability of equipment or personnel may influence the selection of appropriate imaging procedures or treatments. Imaging techniques classified as investigational by the FDA have not been considered in developing these criteria; however, study of new equipment and applications should be encouraged. The ultimate decision regarding the appropriateness of any specific radiologic examination or treatment must be made by the referring physician and radiologist in light of all the circumstances presented in an individual examination.