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Nuchal Translucency inNuchal Translucency in
FirstFirst--Trimester UltrasoundTrimester UltrasoundScreening for Trisomy 21Screening for Trisomy 21
Jane Serene, MS3Jane Serene, MS3
Core Radiology ClerkshipCore Radiology Clerkship
Beth Israel Deaconess Medical CenterBeth Israel Deaconess Medical Center
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Nuchal translucencyNuchal translucency--based screeningbased screeningfor fetal abnormalities has trulyfor fetal abnormalities has truly
become an indispensable aspect ofbecome an indispensable aspect ofcontemporary obstetric practice.contemporary obstetric practice.(Soha Said,(Soha Said, Clinical Obstetrics and Gynecology,Clinical Obstetrics and Gynecology, March 2008)March 2008)
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AgendaAgenda
Introduction to Our PatientsIntroduction to Our Patients
Definition of Nuchal Translucency andDefinition of Nuchal Translucency andMeasurement CriteriaMeasurement Criteria
NT in Trisomy 21 ScreeningNT in Trisomy 21 Screening
Advantages/Limitations of NT ScreeningAdvantages/Limitations of NT ScreeningDifferential Diagnosis of Increased NTDifferential Diagnosis of Increased NT
Mechanisms of Increased NTMechanisms of Increased NT
Fetal Anomalies associated with Increased NTFetal Anomalies associated with Increased NT
FollowFollow--up on Our Patientsup on Our Patients
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Two Patients With Increased Fetal Risk forTwo Patients With Increased Fetal Risk for
Trisomy 21Trisomy 21
Our First PatientOur First Patient
41 year41 year--old, G5P2, withold, G5P2, with
singleton pregnancysingleton pregnancy
Presents for early OBPresents for early OB
ultrasound (
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Defining Nuchal TranslucencyDefining Nuchal Translucency
Fluid between skin andFluid between skin andsoft tissue at back of fetalsoft tissue at back of fetal
neckneck
Can be seenCan be seensonographically in all firstsonographically in all first
trimester fetusestrimester fetuses
Criteria forCriteria forIncreasedIncreased NT:NT:
--NT > 3mmNT > 3mm
--Depends on gestationalDepends on gestationalage (Most accuratelyage (Most accuratelyexpressed as multiple ofexpressed as multiple ofthe median)the median) [3][3]
PACS, BIDMC
Trans-abdominal OB U/S, sagittal view
Increased NT
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Criteria for NT Measurement (1)Criteria for NT Measurement (1)
1.Crown1.Crown--Rump Length = 45Rump Length = 45--84mm (approximately 1184mm (approximately 11--14wks).14wks).
2.Mid2.Mid--sagittal plane with fetus in neutral position:sagittal plane with fetus in neutral position:
Neck flexion decreases NT; Neck extension increases NT.Neck flexion decreases NT; Neck extension increases NT.
PACS, BIDMC
Trans-abdominal OB U/S, sagittal view
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Criteria for NT Measurement (2)Criteria for NT Measurement (2)
3.Enlarge image: upper 2/3 of fetus.3.Enlarge image: upper 2/3 of fetus.4.Identify potential false positives: non4.Identify potential false positives: non--fused amnion, nuchalfused amnion, nuchalcord, neck extension.cord, neck extension.
5.Measure maximal translucency in greatest dimension:5.Measure maximal translucency in greatest dimension:
from outer soft tissue edge to inner nuchal membrane edge.from outer soft tissue edge to inner nuchal membrane edge.
PACS, BIDMC
Trans-abdominal OB U/S, sagittal view
Findings:
1. Nasal Bone
2. Chin
3. Increased NT (4.2mm)
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Inaccurate NT MeasurementInaccurate NT Measurement
BIDMC-PACS
Trans-abdominal OB U/S, sagittal view
1. Not midline view: Nasal bone and chin not visible.
2. Difficult to separate fetal skin from amnion.
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How does NuchalHow does NuchalTranslucency fit intoTranslucency fit into
screening for Trisomy 21?screening for Trisomy 21?
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The Combined TestThe Combined Test
Nuchal Translucency measurementNuchal Translucency measurement
between 11between 11--14 weeks14 weeks
Maternal Serum MarkersMaternal Serum Markers1.Free beta1.Free beta--hCG: Elevated in T21hCG: Elevated in T21
2.Pregnancy2.Pregnancy--associated plasma protein Aassociated plasma protein A(PAPP(PAPP--A): Decreased in T21A): Decreased in T21
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Practice Guidelines for Trisomy 21 ScreeningPractice Guidelines for Trisomy 21 Screening
ACOG 2007: All women should be offeredACOG 2007: All women should be offeredaneuploidy screening before 20wks gestation.aneuploidy screening before 20wks gestation.
--using maternal age alone to triage patients into diagnostic testusing maternal age alone to triage patients into diagnostic testingingmisses 50% of T21 pregnancies that occur in women
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Comparing Screening Methods for T21Comparing Screening Methods for T21
Gestational AgeGestational AgeDetectionDetection
Rate/SensitivityRate/SensitivityFalse PositiveFalse Positive
RateRate
Nuchal Translucency +Nuchal Translucency +
Maternal AgeMaternal Age1111--14 weeks14 weeks 7272--77%77% 4.24.2--5%5%
Combined Test: Age +Combined Test: Age +
NT + PAPPNT + PAPP--A + BetaA + Beta--
hCGhCG1111--14 weeks14 weeks 85%85% 4.84.8
Full Integrated Test:Full Integrated Test:
Combined Test + QuadCombined Test + QuadScreenScreen
1111--14 weeks +14 weeks +
1515--18 weeks18 weeks
85%85%
9090--95%95%
1%1%
2.62.6--5%5%
Serum Integrated Test:Serum Integrated Test:
PAPPPAPP--A + QuadA + Quad
Screen (No U/S)Screen (No U/S)
1111--14 weeks +14 weeks +
1515--18 weeks18 weeks85%85% 3.5%3.5%
Quad Screen: serumQuad Screen: serum
AFP, uE3,AFP, uE3,
hCG, inhibin AhCG, inhibin A
1515--18 weeks18 weeks 85%85% 6.8%6.8%
*All data from FASTER (First and Second Trimester Evaluation of Risk) and SURUSS (Serum, Urine and Ultrasound
Screening Study) Trials.
Barss VA et al. Overview of prenatal screening for Down syndrome. UpToDate 16.1.
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Advantages of Screening withAdvantages of Screening with
The Combined TestThe Combined TestAbnormal TestAbnormal Test
FirstFirst--trimester identificationtrimester identificationof patients at highof patients at high--risk forrisk forfetal anomalies.fetal anomalies.
--Allows for early therapeuticAllows for early therapeutic
abortion.abortion.--Enables preEnables pre--natal planningnatal planningfor care of affected child.for care of affected child.
Triage patients for furtherTriage patients for furthertesting, which improvestesting, which improvescostcost--effective use ofeffective use of
resources.resources.
Normal TestNormal Test
Lowers overall risk ofLowers overall risk ofadvanced maternal ageadvanced maternal agepatients.patients.
--Decreases use of invasiveDecreases use of invasive
diagnostic proceduresdiagnostic procedures(CVS, amniocentesis)(CVS, amniocentesis)
--Decreases procedureDecreases procedure--
associated fetal loss.associated fetal loss.
Reduces anxiety.Reduces anxiety.
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Limitations of The Combined TestLimitations of The Combined Test
NT measurement is operator dependent andNT measurement is operator dependent and
requires special training.requires special training.
A significant number of patients do not getA significant number of patients do not getprenatal care until the 2prenatal care until the 2ndnd trimester.trimester.
20% of obstetric patients are not being offered20% of obstetric patients are not being offeredthis test in spite of research demonstrating itsthis test in spite of research demonstrating itsefficacy.efficacy.
AnxietyAnxiety--provoking when positive. If patients doprovoking when positive. If patients donot want CVS, they must wait 4 weeks fornot want CVS, they must wait 4 weeks foramniocentesis.amniocentesis.
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You identify a neck massYou identify a neck mass
during first trimesterduring first trimesterultrasound screening. Whatultrasound screening. What
do you need to rule outdo you need to rule outbefore diagnosing increasedbefore diagnosing increased
nuchal translucency?nuchal translucency?
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Differential Diagnosis: 1Differential Diagnosis: 1stst Trimester Neck MassTrimester Neck Mass
Hydrops fetalisHydrops fetalis
Cystic HygromaCystic Hygroma
Nonfused amnionNonfused amnion
Nuchal cordNuchal cord
Less Common: BranchialLess Common: Branchial
cleft cyst, hemangioma,cleft cyst, hemangioma,
neuroblastoma.neuroblastoma.
Courtesy ofKoeller KK, et al. Congenital Cystic Masses of the
Neck: Radiologic-Pathologic Correlation. Radiographics,1999;19:121-146.
Trans-abdominal OB U/S, axial view of fetal head
Septated Cystic
Hygroma
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Potential Mechanisms forPotential Mechanisms for
Increased Nuchal TranslucencyIncreased Nuchal Translucency
1.Heart strain/failure
2.Abnormal lymphatic
drainage increased # or
size of lymphatics,
irregular connectionbetween lymphatics and
veins, impaired fetal
movement.
3.Abnormal extracellular
matrix
PACS, BIDMC
Trans-abdominal OB U/S, sagittal view
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Fetal Abnormalities Associated withFetal Abnormalities Associated with
Increased NTIncreased NT
Chromosomally AbnormalChromosomally Abnormal
Trisomy 13Trisomy 13Trisomy 18Trisomy 18
Trisomy 21Trisomy 21
Turners SyndromeTurners SyndromeTriploidyTriploidy
Unbalanced translocationsUnbalanced translocations
Chromosomally NormalChromosomally Normal
CNS defectsCNS defectsDiaphragmatic herniaDiaphragmatic hernia
OmphaloceleOmphalocele
Myotonic DystrophyMyotonic DystrophyEsophageal AtresiaEsophageal Atresia
Infantile PCKDInfantile PCKD
AchondroplasiaAchondroplasia
Fetal AnemiaFetal Anemia
Metabolic defectsMetabolic defects
(and others)(and others)
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Increased NT and Fetal Abnormalities:Increased NT and Fetal Abnormalities:
An Important CaveatAn Important Caveat
Increased NT is NOT a fetal anomaly in and of itself.Increased NT is NOT a fetal anomaly in and of itself.
90% of chromosomally normal fetuses with NT
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Back to Our First PatientBack to Our First Patient
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Patient 1: Fetal Ultrasound
41 y/o G5P2
Sent for early
OB ultrasound
to evaluate NTsecondary to
Advanced
Maternal Age
PAPP-A andbeta-hCG
levels unknown
CRL =55.2mm
PACS, BIDMC
Trans-abdominal OB U/S, sagittal view
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Patient 1: NT Measurement on Fetal USPatient 1: NT Measurement on Fetal US
PACS, BIDMC
Trans-abdominal OB U/S, midline sagittal view
NT = 4.1mm
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Outcome for Our First Patient:Outcome for Our First Patient:
Trisomy 21Trisomy 21
Final NT Measurement = 4.0mmFinal NT Measurement = 4.0mm
FollowFollow--up:up:
1.Amniocentesis at 16 weeks:1.Amniocentesis at 16 weeks: 47, XX, +2147, XX, +212.Full Fetal Survey at 21w6d:2.Full Fetal Survey at 21w6d: common AV canal.
3.Ultrasound at 33w2d:3.Ultrasound at 33w2d: size
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Patient 2: Fetal Ultrasound
40 y/o G3P1
Combined Test
Results:
1.Decreased
PAPP-A
2.Increased
hCG3.Ultrasound
-CRL = 63.6mm
PACS, BIDMC
Trans-abdominal OB U/S, sagittal view
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Patient 2: NT Measurement on Fetal USPatient 2: NT Measurement on Fetal US
PACS, BIDMC
NT = 2.7mm
Trans-abdominal OB U/S, midline sagittal view
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Outcome for Our Second Patient:Outcome for Our Second Patient:
Normal FetusNormal Fetus
Final NT Measurement= 2.6mmFinal NT Measurement= 2.6mm
FollowFollow--up:up:
1.Full Fetal Survey at 16w0d: No abnormalities.1.Full Fetal Survey at 16w0d: No abnormalities.
2.Patient declined amniocentesis.2.Patient declined amniocentesis.
3.Quad Screen at 19w1d: Lowered T21 risk3.Quad Screen at 19w1d: Lowered T21 risk4.Delivered healthy baby girl at 40w5d.4.Delivered healthy baby girl at 40w5d.
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SummarySummary
Nuchal Translucency, as part of the Combined Test, is anNuchal Translucency, as part of the Combined Test, is an
effective and accurate method of screening for fetaleffective and accurate method of screening for fetal
anomalies, especially Trisomy 21.anomalies, especially Trisomy 21.
Sensitive, nonSensitive, non--invasive screening tests ensure that onlyinvasive screening tests ensure that only
those pregnancies at highthose pregnancies at high--risk for abnormalities undergorisk for abnormalities undergo
invasive diagnostic procedures.invasive diagnostic procedures.
Ultrasonographers must be carefully trained in NTUltrasonographers must be carefully trained in NT
measurement.measurement.
All women who receive aneuploidy screening should beAll women who receive aneuploidy screening should be
appropriately counseled and provided with thorough followappropriately counseled and provided with thorough follow--
up.up.
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AcknowledgementsAcknowledgements
Dr. HopeDr. Hope RicciottiRicciotti
Maria LevantakisMaria Levantakis
Dr. Prachi DubeyDr. Prachi Dubey
Dr. Rola ShaheenDr. Rola ShaheenDr. Colin McCardleDr. Colin McCardle
Dr. Gail BirchDr. Gail BirchDr. Gillian LiebermanDr. Gillian Lieberman
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ResourcesResources
ACOG Practice Bulletin 77: Screening for Fetal Chromosomal AbnorACOG Practice Bulletin 77: Screening for Fetal Chromosomal Abnormalities.malities. Obstetrics andObstetrics and
Gynecology, 109:1.Gynecology, 109:1. Jan. 2007.Jan. 2007.
Barss VA, et al. Overview of prenatal screening for Down syndroBarss VA, et al. Overview of prenatal screening for Down syndrome.me. UpToDate 16.1UpToDate 16.1. (5/23/08). (5/23/08)
Benacerraf, BR. The sonographic diagnosis of fetal aneuploidy.Benacerraf, BR. The sonographic diagnosis of fetal aneuploidy. UpToDate 16.1. (5/16/08)UpToDate 16.1. (5/16/08)
Jackson M and Rose NC. Diagnosis and Management of Fetal NuchalJackson M and Rose NC. Diagnosis and Management of Fetal Nuchal Translucency.Translucency. SeminarsSeminars
in Roentgenology,in Roentgenology, Vol XXXIII, No 4. Oct. 1998: pp333Vol XXXIII, No 4. Oct. 1998: pp333--338.338.
Koeller KK, et al. Congenital Cystic Masses of the Neck: RadKoeller KK, et al. Congenital Cystic Masses of the Neck: Radiologiciologic--Pathologic Correlation.Pathologic Correlation.
Radiographics,Radiographics, 1999;19:1211999;19:121--146.146.
Kurtz AB and Needleman L. American College of Radiology StandarKurtz AB and Needleman L. American College of Radiology Standards: Obstetricalds: ObstetricalMeasurements.Measurements. Seminars in Roentgenology,Seminars in Roentgenology, Vol XXXIII, No 4. Oct. 1998: pp. 309Vol XXXIII, No 4. Oct. 1998: pp. 309--332.332.
Nyberg DA, et al. FirstNyberg DA, et al. First--Trimester Screening.Trimester Screening. Radiologic Clinics of North America.Radiologic Clinics of North America. 2006;44: 8372006;44: 837--
861.861.
Reeder, MM.Reeder, MM. Gamuts in Radiology: Comprehensive List of Roentgen DifferentialGamuts in Radiology: Comprehensive List of Roentgen Differential Diagnosis.Diagnosis. 44thth
Ed. New York: Springer, 2003.Ed. New York: Springer, 2003.Said S, Malone FD. The Use of Nuchal Translucency in ContemporaSaid S, Malone FD. The Use of Nuchal Translucency in Contemporary Obstetric Practice.ry Obstetric Practice.
Clinical Obstetrics and Gynecology.Clinical Obstetrics and Gynecology. 51:1. March 2008.51:1. March 2008.